Chapter 9: Light, Lamps & Electricity

Marijuana Horticulture: The Indoor / Outdoor Medical Grower’s Bible

by Jorge Cervantes

Light, Spectrum, and Photoperiod

Marijuana needs light to grow. The light must have the proper spectrum and intensity to ensure rapid growth. Light is comprised of several bands of colors. Each color in the spectrum sends the plant a separate signal. Each color in the spectrum promotes a different type of growth.

PAR and Light Spectrum

Plants need and use only certain portions of the light spectrum. The most important colors in the spectrum for maximum chlorophyll production and photosynthetic response are in the blue and red range. The main portion of light used by plants is between 400 and 700 nanometers. This region is called the Photosynthetically Active Radiation (PAR) zone.

“PAR watts” is the measure of the actual amount of specific photons a plant needs to grow. Photons are a measure of light energy. Light energy is radiated and assimilated in photons. Photosynthesis is necessary for plants to grow and is activated by the assimilation of photons. Blue photons are worth more PAR watts than red photons, but scientists have difficulty measuring the exact difference.

Each color of light activates different plant functions. Positive tropism, the plant’s ability to orient leaves towards light, is controlled by spectrum. Light bulbs deliver only a part of the necessary light marijuana needs to grow. However, they deliver enough! Most of marijuana’s light needs can be met by artificial means.

Measuring Light

Virtually all light is measured in foot-candles, lux, or lumens. Foot-candles and lux measure light visible to the human eye. The human eye sees much less of the light spectrum than the plants “see”. The eye is most sensitive to light between 525-625 nanometers. The importance of the red and blue portions in the spectrum is diminished greatly when light is measured in foot-candles, lux, or lumens. A foot-candle is a unit of illumination equal to the intensity of one candle at a distance of one foot. The lux scale is similar to that of the foot-candle; one foot-candle is equal to 10.76 lux.

Humans see light differently than plants do. Plants use the photosynthetically active response (PAR) portion of the spectrum. Human use the central portion of the spectrum, while plants are able to use large portions of the spectrum not measured by light meters that record foot-candles, lux, and lumens.

Light is also measured in spectrum with Kelvin temperature which expresses the exact color a bulb emits. Bulbs with a Kelvin temperature from 3000 to 6500 are best for growing marijuana. The PAR section explains that plants use specific portions of the spectrum – a complete range from blues too reds. Lamps with a spectrum similar to PAR-rated bulbs can use Kelvin temperature of a bulb to ascertain the approximate PAR rating for the lamp. Color spectrum results from a specific mix of different colors. High intensity discharge bulbs are very similar in spectrum. Making these safe assumptions, a rough PAR rating could be extrapolated from a Kelvin temperature rating.

The Color Corrected Temperature (CCT) of a bulb is the peak Kelvin temperature at which the colors in a bulb are stable. We can classify bulbs by their CCT rating which tells us the overall color of the light emitted. It does not tell us the concentration of the combination of colors emitted. Companies use a Color Rendering Index (CRI). The higher the CRI, the better the bulb is for growing.

Light Meters

Most commercial light meters measure light in foot-candles or lux. Both scales measure light which the human eye reacts to “see”. They do not measure photosynthetic response to light in PAR watts.

Light measurements in this book are made in foot-candles and lux. This information is still valuable, because it record the amount of light spread over a specific surface. The information is often coupled with the PAR rating of different bulbs. Regardless of the lamp, the amount of light emitted is constant. It only makes sense to use a proper reflective hood with a high PAR-rated bulb to grow the best garden.

After all the talk about PAR watts, industry officials are unable to agree on a common scale of measurement. For this reason, we have decided to rely on Kelvin color temperature to measure lamp spectrum.


The photoperiod is the relationship between the duration of the light period and dark period. Most strains of marijuana will stay in the vegetative growth stage as long as an 18-24 hour light and a 6-0 hour dark photoperiod is maintained. However, there are exceptions. Eighteen hours of light per day will give marijuana all the light it needs to sustain vegetative growth.

Flowering is most efficiently induced with 12 hours of uninterrupted darkness in a 24 hour photoperiod. When plants are at least two months old, after they have developed sexual characteristics, altering the photoperiod to an even 12 hours, day an night, will induce visible signs of flowering in one to three weeks. Older plants tend to show signs f flowering sooner. Varieties originating in the tropics generally mature later. The 12 hour photoperiod represents the classic equinox and is the optimum daylight-to-dark relationship for flowering cannabis.

Research has proven that less than 12 hours of light will not induce flowering and faster and reduces flower formation and yield. More than 12 hours of light often prolongs flowering. Some growers have achieved higher yields by inducing flowering via the 12-hour photoperiod, then changing to 13-14 hours of light after two to four weeks. However, flowering is often prolonged. I spoke with growers who increase light by one hour two to three weeks after flowering is induced. They say the yield increases about 10 percent. Flowering takes about a week longer, and different varieties respond differently.

A relationship exists between photoperiod response and genetics. We can make generalizations about this relationship, because little scientific evidence documents the extent to which specific strains of cannabis are affected by photoperiod. For example, sativa-dominant plants that originated in the tropics respond to long days better than indica-dominant plants. On the equator, days and nights are almost the same length year round. Plants tend to bloom when they are chronologically ready, after completing the vegetative growth stage. However, most growers are familiar with a pure sativa strain, Haze, which flowers slowly for three months or longer, even when given a 12-hour photoperiod. You can start Haze on a 12/12 day/night schedule, but it still must go thru the seedling and vegetative stages before spending three months or longer flowering. Plants grow more slowly in 1-hour days than when given 18 hours of light, and inducing flowering takes longer.

Indica-dominant varieties that originated in northern latitudes tend to flower sooner and respond more quickly to a 12-hour photoperiod. Many indica varieties will flower under a 14/10 or 13/11 day/night photoperiod. Again, the hours of light necessary to induce flowering in an indica-dominant plant is contingent upon the genetics in the strain. More hours of light during flowering can cause some strains to produce bigger pants with reduced flowering time, but some growers have reported looser, leafier buds as a result.

Giving any cannabis variety less than 12 hours of uninterrupted darkness will not make it flower faster. Instead, the plant will take longer to mature, its buds will be smaller, and the overall harvest will be lessened.

genetically unstable strains could express hermaphroditic tendencies if the photoperiod bounces up and down several times. If you plan to give plants a photoperiod of 13/11 day/night, stick to it. Do not decide you want to change the photoperiod to 15/9. Such variation will stress plants and could produce hermaphrodites.

Some growers experiment with gradually decreasing daylight hours while increasing hours of darkness. They do this to simulate the natural photoperiod outdoors. This practice prolongs flowering and does not increase yield.

The photoperiod signals plants to start flowering; it can also signal them to remain in (or revert to) vegetative growth. Marijuana must have 12 hours of uninterrupted , total darkness to flower properly. Dim light during the dark period in the pre-flowering and flowering stages prevents marijuana from blooming. When the 12-hour darkness period is interrupted by light, plants get confused. The light signals plants, “It’s daytime; start vegetative growth.” Given this signal of light, plants start vegetative growth, and flowering is retarded or stopped.

Marijuana will not stop flowering if the lights are turned on for a few minutes once or twice during the flowering cycle. If a light is turned on for a few minutes – long enough to disrupt the dark period – on two or three consecutive nights, plants will start to revert to vegetative growth. Less than one half of one foot-candle of light will prevent cannabis from flowering. That is a little more light than reflected by a full moon on a clear night. Well-bred indica-dominant plants will revert within three days. Sativa-dominant plants will take four or five days to revert to vegetative growth. Once they start t re-vegetate, it take four to six additional weeks to induce flowering!

When light shines on a green object, green pigment in the object absorbs all spectrum colors but green, and the green light is reflected. This is why we see the color green.

The smart way to visit a grow room during a dark period is to illuminate it with a green light. Marijuana does not respond to the green portion of the light spectrum, thus a green bulb is usable in the grow room at night with no ill effects.

Some growers leave the HID on 24 hours a day. Marijuana can efficiently process 16 t 18 hours of light per day, after which it reaches a point of diminishing returns, and the electricity is wasted.

I talked with Dutch and Canadian growers who claim their plants flower under a 6-hour dark and 12-hour light photoperiod. This expedited, 18-hour photoperiod regimen is supposed to work, but I’m not sold on it. Growers say that their harvest is undiminished, and that they are getting 25 percent more marijuana at the same time. I have not visited their grow rooms to verify these claims. No electricity is saved by adopting this regimen.


High intensity discharge lamps are bright – very bright. Growers who properly manage this intense brightness harvest more weed per watt. Intensity is the magnitude of light energy per unit of area. It is greatest near the bulb and diminishes rapidly as it moves away from the source.

For example, plants that are two feet from a lamp receive one-fourth of the amount of light received by plants on foot away! An HID that emits 100,000 lumens produces a paltry 25,000 lumens two feet away. A 1000-watt HID that emits 100,000 initial lumens yields 11,111 lumens three feet away. Couple this meager sum with a poorly designed reflective hood, and beautiful buds suffer big time! The closer marijuana is to a light source, the more PAR watts it receives and the better it grows, as long as it is not so close that heat from the lamp burns foliage.

The Inverse Square Law

The relationship between light emitted from a point source (bulb) and distance are defined by the inverse square law. This law affirms that the intensity of light changes in inverse proportion to the square of the distance. Intensity = light output / distance sq

A 1000-watt standard metal halide emits from 80,000 to 110,000 initial lumens and 65,000 to 88,000 average (mean) lumens. One lumen is equal to the amount of light emitted by one candle that falls on one square foot of surface one foot away. Super halides emit 115,000 initial lumens and 92,000 mean lumens. A 1000-watt HP sodium emits 140,000 initial lumens, and a 600-watt HP Sodium emits 90,000; watt for watt, that’s seven percent more lumens than the 1000-watt HPS. Lumens received by the plant are much more important.

Lumens received are measured in watts-per-square-fot or in foot-candles. One foot candle equals the amount of light that falls on one square foot of surface located one foot away from one candle.

Watts-per-square-foot is easy to calculate, but is an enormous way to determine usable light for a garden. It measures how many watts are available from a light source in the area. For example, a 400-watt incandescent bulb emits the same watts-per-square-foot as a 400-watt metal halide. Mounting height is not considered in watts-per-square-foot; the lamps could be mounted at any height from four to eight feet. Nor does it consider PAR watts or efficiency of the bulb.

Calculating foot-candles or lux is a more accurate way to estimate the amount of light plants receive, but still lacks the precision of measuring how much light is used by plants. If you start with a bulb that is rated in PAR watts, using a foot-candle or lux meter will suffice.

To demonstrate how dim light intensity retards plant development, check out an outdoor vegetable garden. Have you ever planted 65-day broccoli that took 100 days to mature? Most gardeners have suffered this fate. Did the plants get full sun all day long? The seed vendor assumes seeds were planted under perfect conditions – full sun and perfect temperature range. Plants that received less PAR light matured slowly and produced less than plants getting full sun all day long. It is the same in an indoor marijuana garden; plants that receive less light grow poorly.

Lamp Spacing

Light intensity virtually doubles for every six inches closer an HID is to the canopy of a garden. When light intensity is low, plants stretch for it. w light intensity is often caused by the lamp being too far away from plants. Dim light causes sparse foliage and spindly branches that are further apart on the stem.

Increase yield by giving growing area uniform light distribution. Uneven light distribution causes strong branch tips to grow toward the intense light. Foliage in dimly lit areas is shaded when light distribution is uneven.

Reflective hoods ultimately dictate amp placement – distance between lamps and above the plants. Nearly all stationary amps have bright (hot) spots that plants grow toward.

Growers prefer high wattage lamps – 400, 600, 1000, or 1100 watts – because they have lumens per watt and their PAR rating is higher than smaller bulbs. Plants receive more light when the lamp is closer to the garden. Even though 400-watt lamps produce fewer lumens-per-watt than a 1000-watt bulb, when properly setup, they actually deliver more usable light to plants. The 600-watt bulb has the highest lumen-per-watt conversion and can be placed closer to the canopy of the garden than a 1000 or 1100-watt bulb. When the 600-watt bulb is closer to pants, they receive more light.

A 1000-watt HID emits a lot of light. It also radiates a lot of heat. The bulb must be farther away from the plants to avoid burning them. In many cases it is more effective to use smaller wattage bulbs. For example, two 400-watt bulbs can be placed closer to plants than one 1000-watt bulb, and the 400-watt bulbs emit light from two pints. The disadvantage is that two 400-watt systems cost more than one 1000-watt system.

Although 400-watt lamps have a lower lumen-per-watt conversion, when used properly they may be more efficient than higher wattage bulbs. One 1000-watt halide produces 115,000 initial lumens and 400-watt halide only 40,000. This means each 400-watt lamp must be located closer to the canopy of the garden to provide a similar amount of light. It also means that several different point sources sustain more even, intense light distribution.

Side Lighting

Side lighting is generally not as efficient as lighting from above. Vertically oriented lamps without reflectors are efficient, but require plants to be oriented around the bulb. To promote growth, light must penetrate the dense foliage of a garden. The lamps are mounted where light intensity is marginal – along the walls – to provide sidelight.

Rotating Plants

Rotating plants will ensure even distribution of light. Rotate plants every day r two by moving them one quarter to one half turn. Rotating promotes even growth and fully developed foliage.

Move plants around under the lamp so they receive the most possible light. Move smaller plants toward the center and taller plants toward the outside of the garden. Set small plants on a stand to even out the garden profile. Arrange plants in a concave shape (stadium method) under the lamp so all plants receive the same amount of light. Containers with wheels are easier to move.

Take advantage of the different levels of light below the HID. Place seedlings and cuttings requiring low light eves on the perimeter and flowering plants. needing higher light levels under bright bulbs.

Plant Spacing

When light shines on a garden, the leaves near the top of pants get more intense light than the leaves at the bottom. The top leaves shade the bottom leaves and absorb light energy, making less light energy available to lower leaves. If the lower leaves do not receive enough light, they will yellow and die. Tall six foot plants take longer to grow and have higher overall yields than shorter four-foot plants, but the yield of primo tops will be about the same. Due to lack of light, the taller plants have large flowers on the top three to four feet and spindly buds nearer the bottom. Tall plants tend to develop heavy flower tops whose weight the stem cannot support. These plants need to be tied up. Short plants better support the weight of the tops and have much more flower weight than leaf weight.

At least 99 two week old seedlings or clones can be huddled directly under a single 400-watt HID. The young plants will need more space as they grow. If packed too closely together, plants sense the shortage of space and do not grow to their maximum potential. Leaves from one plant shade another plant’s foliage and slow overall plant growth. It is very important to space young plants just far enough apart so their leaves do not touch or touch very little. This will keep shading to a minimum and growth to a maximum. Check and alter the spacing every few days. Eight to sixteen mature females three to four months old will completely fill the space under one 1000-watt HID.

Plants can absorb light only if it falls on their leaves. Plants must be spaced so their leaves do not overlap too much. Yield increases very little when plants are crowded. Plants also stretch for light, which makes less efficient use of intense light.

best number of plants per square for is often a matter of experimenting to find the magic number for your garden. In general, each 40-inch-square space will hold from 16 to 32 plants.

Reflective Hoods

Some reflective hoods reflect light more evenly than others. A reflector that distributes the light evenly – with no hot spots – can be placed closer to plants without burning them. These hoods are most efficient, because the lamp is closer and the light more intense. The farther the lamp is from the garden, the less light plants receive. For example, a 1000-watt reflector with a hot spot must be placed 36 inches above the garden. A 600 watt lamp with a reflector that distributes light evenly can be placed only 18 inches above the garden. When placed closer, the 600-watt lamp shines as much light on the garden as the 1000-watt bulb!

The proper reflective hood over the lamp and reflective walls can double the growing area. growers who use the most efficient reflective hoods harvest up to twice as much as those who don’t.

Seedlings, cuttings, and plants in the vegetative growth stage need less light than flowering plants, because their growth requirements are different. For the first few weeks of life, seedlings and clones can easily survive beneath fluorescent lights. Vegetative growth requires a little more light, easily supplied by a metal halide or compact fluorescent lamps.

Reflective hoods are made from steel sheet metal, aluminum, even stainless steel. The steel is either cold-rolled or pre-galvanized before a reflective coating is applied. Pre-galvanized steel is more rust resistant than cold-rolled steel. This metal can be polished, textured or painted, with white being the most common paint color. Premium hood manufacturers apply white paint in a powder coating process.

The pebble a hammer-tone surfaces offer good light diffusion and more surface area to reflect light. hot spots are commonplace among highly polished, mirror-like surfaces. Mirror-polished hods also scratch easily and create uneven lighting.

Horizontal Reflective Hoods

Horizontal reflectors are most efficient for HID systems, and are the best value for growers. A horizontal lamp yields up to 40 percent more light than a lamp burning in a vertical position. Light is emitted from the arc tube. When horizontal, half of this light is directed downward to the plants, so only half of the light needs to be reflected. horizontal reflectors are inherently more efficient than vertical lamps / reflectors, because half of the light is direct and only half of the light must be reflected.

Horizontal reflective hoods are available in many shapes and sizes. The closer the reflective hood is to the arc tube, the less distance light must travel before being reflected. less distance traveled means more light reflected.

Horizontal reflective hoods tend t have a hot spot directly under the bulb. To dissipate this hot spot of light and lower the heat it creates, some manufacturers install a light deflector below the bulb. The deflector diffuses the light and heat directly under the bulb. When there is no hot spot, reflective hods with deflectors can be paced closer to plants.

Horizontally mounted HP sodium lamps use a small reflective hood for greenhouse culture. The hood is mounted a few inches over the horizontal HP sodium bulb. All light is reflected down toward plants, and the small hood creates minimum shadow.

Vertical Reflective Hoods

Reflectors with vertical lamps are less efficient than horizontal ones. Like horizontal bulbs, vertically mounted bulbs emit light from the sides of the arc tube. This light must strike the side of the hood before it is reflected downward to the plants. Reflected light is always less intense than original light. Light travels farther before being reflected in parabolic or cone reflective hoods. Direct light is more intense and more efficient.

Parabolic dome reflectors offer the best value for vertical reflectors. They reflect light relatively evenly, though they throw less overall light than horizontal reflectors. large parabolic dome hoods distribute light evenly and reflect enough light to sustain vegetative growth. The light spreads out under the hood and is reflected downward t plants. Popular parabolic hoods are inexpensive t manufacture and provide a good light value for the money. Four foot parabolic hoods are usually manufactured in nine parts. The smaller size facilitates shipping and handling. The customer assembles the hood with small screws and nuts.

Four-foot cone hoods are usually manufactured in four parts. The smaller size facilitates shipping and handling. The customer assembles the pieces with small screws and nuts. Cone shaped reflectors use a vertical bulb waste light and are very inefficient. Growers who try to save money by purchasing cone-shaped reflectors pay even more in lost efficiency.

Lightweight reflective hoods with pen ends dissipate heat quickly. Extra air flows directly through the hood and around the bulb in open end fixtures to cool the bulb and the fixture. Aluminum dissipates heat more quickly than steel. Train a fan on reflective hoods to speed heat loss.

Artificial light fades as it travels from its source (the bulb). The closer you put the reflector to the bulb, the more intense the light it reflects.

Enclosed hoods with a glass shield covering the bulb operate at higher temperatures. The glass shield is a barrier between plants and the hot bulb. Enclosed hods must have enough vents; otherwise heat build up in the fixture causes bulbs to burn out prematurely. Many of these enclosed fixtures have a special vent fan to evacuate hot air.

Air-Cooled Lamp Fixtures

Several air-cooled lights are available. Some use a reflective hood with a protective glass face and two squirrel cage blowers to move air through the sealed reflective hood cavity. The air is forced to travel around corners, which requires a higher velocity f airflow. Other air-cooled reflectors have no airflow turns, so the air is evacuated quickly and efficiently.

Water-Cooled Lamp Fixtures

Water-cooled and air-cooled lamp fixtures are somewhat popular in hot climates. These lamps run cooler and can be moved closer to plants. Water-cooled bulbs are difficult for thermal imaging equipment to detect. Air-cooled fixtures are inexpensive to operate and easy to setup. Keep outer jacket clean and avoid scratching.

Growers decrease bulb heat by 80 percent with a properly setup water cooled bulb. The water and outer jacket account for a ten percent lumen loss. Growers make up for this loss by moving bulbs closer to plants. On an average day, a 1000-watt bulb uses about 100 gallons of water to keep cool, if the water runs to waste. To recirculate, the water requires a big, big reservoir. The water in the reservoir that serves a recirculating cooling system must also be cooled. Reservoir coolers can easily cost $1000.

No Reflective Hood

One option is to remove the reflective hood. With no hood, the lamp burns cooler and emits only direct light.

Reflective Hood Study

I constructed a black room, everything black inside, t measure the amount of light reflective hoods yield. The room was 10 x 10 foot square. The floor was covered with black tar paper. Less than three percent light could be reflected from the black surfaces – there was no extra light in this room. Measurements were made every 12 inches on a matrix marked on the floor. The walls had one-foot increments marked.

I tested five different amps; a 1000-watt clear super metal halide, a 1000-watt HP sodium, a 600-watt HP sodium, a 400-watt super metal halide, and a 400-watt HP sodium. I positioned the bulb exactly three feet from the floor. Every amp was warmed up for 15 minutes before taking measurements.

The foot-candle readings on the floor were taken every 12 inches and the results posted to a spreadsheet program. I used a simple spreadsheet graph program t present the graphic results.

The studies show a huge difference between reflective hoods. Some companies do not test their hoods before putting them on the market. To protect yourself and your plants, set up tests like the ones I did here to find out which reflector is the best for your needs.

When a reflector distributes light evenly, the amp can be placed closer to plants.

In general, the larger the wattage of the bulb, the more efficient it is. Since light intensity diminishes so quickly, bulbs must be close to plants. Consequently, more lamps r point sources of light are necessary for even distribution of bright light.

Operating costs for three 600-watt HPS lamps are lower than for two 1000-watt HPS lamps. The 600-watt lamps produce more lumens for the same amount of money, plus they can be closer to plants. There are also three point sources of light, which evens out distribution.

A heat vent outlet around the bulb helps dissipate heat into atmosphere. Excessive heat around the bulb causes premature burnout.

Reflective Light

Flat white contains little or no light absorbing pigment, so it absorbs almost no light and reflects almost all light. Do not use glossy white. It contains varnish that inhibits reflective light. A matte texture provides more reflective surface.

Foylon is a reflective material that reflects light and heat in an evenly dispersed pattern. It is durable, and it reflect about 95 percent of the light that hits it. The material is plied with rip-stop fiber and is thick enough to act as an insulator.

Reflective Mylar provides one of the most reflective surfaces possible. Mylar looks like a very thin mirror. Unlike light absorbing paint, Reflective Mylar reflects almost all light. To install Reflective Mylar, simply tape or tack to the wall. T prevent rips or tears, place a piece of tape over the spot where the staple, nail or tack will be inserted. Although expensive, Mylar is preferred by many growers. The thick is to position it flat against the wall. When loosely affixed to surfaces, light is poorly reflected. To increase its effectiveness, keep Reflective Mylar clean.

Aluminum foil is one of the worst possible reflective surfaces. The foil always crinkles up and reflects light in the wrong directions – actually wasting light. It also reflects more ultraviolet rays than other surfaces, which are harmful to chloroplasts in leaves.

Mirrors also reflect light, but much less than Mylar. Light must first pass through the glass in the mirror, before it is reflected back through the same glass. Light is lost when passing through the glass.

More Free Growing Light

Even though the lumens-per-watt conversion is lower with 400-watt bubs than 1000-watt bulbs, hanging ten 400-watt amps over the same area that four 1000-watt amps cover, provides more even distribution of light and minimizes shading. Three 600-watt lamps that produce 270,000 lumens from three point sources, instead of two 1000-watt HP sodiums yielding 280,000 lumens from two points, lower total light output by 10,000 lumens, but increases the number of sources of light. Lamps can be placed closer to plants, increasing efficiency even more.

Manually rotating plants helps them fill out better, promoting more even development. The monger plants are in their flowering growth stage, the more light they need. During the first three to four weeks of flowering, plants process a little less light than the last three to four weeks. Pants flowering during the last three to four weeks are placed directly under the bulb where light is brightest. Plants that have just entered the flowering room can stay on the perimeter until the more mature plants are moved out. This simple trick can easily increase harvests by five to ten percent.

When plants get big, it can become laborious to rotate them. Difficult jobs often go undone. Save the strain and use a light mover, or put the containers on wheels.

Add a shallow shelf around the perimeter f the garden t use light that is eaten by the walls. This sidelight is often very bright and very much wasted. Use brackets to put up a four to six inch wide shelf around the perimeter of the garden. The shelf can be built on a sight angle and lined with plastic to form a runoff canal. Pack small plants in six inch pots along the shelf. Rotate them so they develop evenly. These plants can either flower on the short shelf or when moved under the light.

Installing rolling beds will remove all but one walkway from the garden. greenhouse growers learned long ago t save space. We can use the same information t increase usable grow space in a grow room. Gardens with elevated grow beds often waste light on walkways. To make use of more growing area place two, two inch pipes or wooden dowels below the growing bed. The pipe allows the beds t be rolled back and forth, so only one walkway is pen at a time. This simple trick usually increases growing space by about 25 percent.

Growing a perpetual crop and flowering only a portion of the garden allows for more plants in a smaller area and a higher overall yield. More plants receive intense light, and no light is wasted in such a garden.

Light Movers

Replicate the movement of the sun through the sky with a motorized light mover. A light mover is a device that moves amps back and forth or in circles across the ceiling of a grow room. The linear or circular path distributes light evenly. Use a light mover to get lights closer to plants. Keep plants at east 12 inches away from a lamp on a light mover. The closer a lamps is to plants without burning them, the more light plants get!

Light movers make bright light distribution more even. Uniform light distribution makes cannabis grow evenly. Budding branches tend to grow toward and around stationary HIDs. These extra tall spikes of buds shade other foliage. More pants receive more intense light with a lamp moving overhead. This is not a substitute for more lumens from an additional lamp. It is a more efficient way to use each HID, especially 1000-watt lamps. A lamp that is directly overhead casts more direct, intense light to a greater number of plants.

Slower-moving light movers are generally more reliable. Fast-moving light movers can cause light weight reflectors to wobble or list.

Light from a stationary bulb always shines with the same intensity in the same spot. If upper foliage shades lower eaves, grows sows and is uneven. Light, received by plants from several directions, shines more intensely on more foliage. The light energy is being processed by more foliage and promotes even growth. In nature, as the sun arc overhead, the entire plant gets full benefit of of the light. Most varieties of cannabis grow into a classic Christmas tree shape. This is the most efficient configuration for the plant’s growth. Light reaches the center of the plant as well as all outside parts.

Commercial light movers supply more intense light to more plants for less money. Growers report that light movers make it possible t use fewer lamps to get the same yield. Light movers increase light coverage by 25 to 35 percent. According to some growers, three amps mounted on motorized light movers will do the job of four lamps.

Motorized light movers keep an even garden profile. The HID draws about 9.2 amperes (A). If this lamp is on a 15 or 20 ampere circuit, you can easily add a light mover that draws one more ampere to the circuit with no risk or overload.

Linear systems move in a straight line simulating the sun’s path through the heavens. A linear system increases intense light to plants in a linear oval. The area covered by a light mover depends on the length of the track and the number of lamps. The systems use a tracks that affixes to the ceiling. The lamp moves back and forth across the ceiling, guided by the track. The lamp is fastened to the mover with an adjustable chain r cord. These units vary in length and the speed at which the lamp travels. Some are designed for one lamp, while others are able to move six lamps efficiently. A six foot linear light mover increases optimum coverage of light from 36 to 72 square feet.

Young clones and seedlings might stretch and become leggy if the lamp travels too far away. Start using the light movers after the plants are 12 inches tall and have several sets of leaves.

Planter boxes or containers on wheels offer a good alternative to light movers. Containers are rotated daily; wheels make this job a snap. Light reaches every corner of the garden without having to move the lamp. This method has a similar effect as moving the lamp overhead, but is more work because all plants have to be moved, rather than only one or two lamps.

High Intensity Discharge (HID) Lights

Growers use HID lamps to replace natural sunlight indoors and grow outstanding cannabis. High intensity discharge lamps outperform all other lamps in their lumens-per-watt efficiency, spectral balance, and brilliance. The spectrum and brilliance of HIDs hep growers replicate growth responses induced in cannabis in natural sunlight. Compare charts on HID spectral emission with the chart on photosynthetic response, chlorophyll synthesis, and positive tropism.

The HID lamp family contains mercury vapor, metal halide, High Pressure (HP) sodium, and conversion bulbs. Metal halide, HP sodium, and conversion lamps have a spectrum similar to actually sunshine and can be used to grow marijuana. Mercury vapor l;amps were the first HIDs on the market. Obsolete mercury vapor lamps are inefficient electrically and produce a poor spectrum for plant growth. Now most all mercury vapor lamps have been retrofitted with more efficient HIDs.

Researchers have created a few better bulbs with a higher PAR rating, but there is no new technology in sight. The latest glass covers of the bulb have become slightly better at letting light through, but there have been very few major technical advances in these bulbs for the last 20 years.

Incandescent bulbs are the least efficient; 600-watt HP sodium lamps are the most efficient. The brightest bulbs measured in lumens-per-watt are the metal halide and HP sodium bubs.

Originally developed in the 1970s, metal halides and HP sodium bulbs were characterized by one main technical limitation – the larger the bulb, the higher the lumen-per-watt conversion. For example, watt for watt, a 1000-watt HP sodium produces about 12 percent more light than a 400-watt HPS and about 25 percent more light than a 150-watt HPS. Scientists overcame this barrier when they developed the 600-watt HP sodium. Watt for watt, a 600-watt HPS produces seven percent more light than the 1000-watt HPS. The “pulse start” metal halides are also brighter and much more efficient than their predecessors.

High intensity discharge lamps produce light by passing electricity through vaporized gas enclosed in a clear ceramic arc tube under very high pressure. The dose, or combination of chemicals, sealed in the arc tube determines the color spectrum produced. The mix of chemicals in the arc tube allows metal halide lamps to yield the broadest and most diverse spectrum of light. The spectrum of HP sodium lamps is somewhat limited because of the narrower band of chemicals used to dose the arc tube. The arc tube is contained within a larger glass bulb. Most of the ultraviolet (UV) rays produced in the arc tube are filtered out by the outer bulb. Never look at the arc tube if the outer bulb breaks. Turn off the lamp immediately. Some bulbs have a phosphor coating inside the bulb. This coating makes them produce a little different spectrum and fewer lumens.

General Electric, Iwasaki, Lumenarc, Osram / Sylvania, Philips, and Venture (SunMaster) manufacture HID bulbs. These companies construct many bulbs with the exact same technical statistics. According to some gardeners, certain brands of bulbs are better than others because of where they are manufactured. They usually came t this conclusion because because they purchased two different brands of (1000-watt) bulbs and had better luck using one brand. What these gardeners don’t know is that many f the manufacturers buy and use the same components, often manufactured by competitors!

Pulse-start metal halides commonly use 240 volts and harbor the started in the ballast box, not in the arc tube. These systems employ physically smaller reactor ballasts that keep original line voltage within ten percent of the voltage in the arc tube.

reflective walls increase light in the growing area. Less intense light on the perimeter of gardens is wasted unless it is reflected back onto foliage. Up to 95 percent of this light can be reflected back toward plants. For example, if 500 foot-candles of light is escaping from the edge of the garden and is reflected at the rate f 50 percent, then 250 foot-candles will be available on the edge of the garden.

Reflective walls should 12 inches or less from the plants for optimum reflection. Ideally, take walls to the plants. The easiest way to install mobile walls is to hang the amps near the corner of a room. Use two corner walls to reflect light. Move the two outside walls close to plants to reflect light. Make the mobile walls from lightweight plywood, Styrofoam, or white Visqueen plastic.

Using white Visqueen plastic to “white out” a room is quick and causes no damage to the room. Visqueen plastic is inexpensive, removable, and reusable. It can be used t fabricate walls and partition rooms. Waterproof Visqueen also protects the walls and floor from water drainage. Lightweight Visqueen es easy to cut with scissors or a knife and can be stapled, nailed, or taped.

To make the white walls opaque, hang black Visqueen on the outside. The dead air space between the two layers of Visqueen also increases insulation.

Using flat white paint is one of the simplest, east expensive, most efficient ways to create optimum reflection. Artists’ titanium white paint is more expensive, but more reflective. While easy to clean, semi-gloss white is not quite as reflective as flat white. Regardless of the type of white used, a non-toxic, fungus inhibiting agent should be added when paint is mixed. A gallon of good flat white paint costs less than $25. One or two gallons should be enough to “white out” the average grow room. but do not paint the floor white – the reflection is detrimental to tender leaf undersides. Use a primer coat to prevent bleed-through of dark colors or stains or if walls are rough and unpainted. Install the vent fans before painting. Fumes are unpleasant and can cause health problems. Painting is labor-intensive and messy, but it’s worth the trouble.

HID Ballasts

A ballast regulates specific starting requirements and line voltage for specific HID lamps. Wattages from 150-1100 use old-fashioned coil transformer-type ballasts. Smaller wattages – below 100 – use energy efficient electronic ballasts. Electronic ballasts run cool and quiet. Scientists continue to develop electronic ballasts for larger wattage HIDs, but the failure rate is still very high. It is very important to buy the proper ballast for your HID. Smart growers buy the entire HID system – ballast, amp, socket, connecting wiring, and timer – at the same time from a reputable supplier to ensure the ballast and lamp go together.

Be careful when purchasing ballasts that are made in China or Asia, in general. Many of these ballasts are poorly made and do not meet local safety standards. Do not be tricked by misleading sales phrases such as “all components UL or CSA approved”. Of course, each of the components could be UL or CSA approved, but when the components are used together to operate a lamp, they are not UL or CSA approved. Furthermore, chances are that if components are approved, they are not approved for the specific application. Cheap transformers, capacitors, and starters are cheap because they are of inferior quality.

Do not try t mix and match ballasts and amps. Just because a amp fits a socket attached to a ballast, does not mean it will work properly in it. If you use the wrong ballast, capacitor, or starter with a amp, the lamp will not produced the rated amount of light, and it will burn out sooner. The wrong amp plugged into the wrong ballast adds up to a burnout!

The “core”, or transformer, consists of metal pates stuck together by resin and wound with copper wire. The capacitor can is on the right under the connecting wires.

More economical ballasts kits contain a transformer core, capacitor (HPS and some metal halides), starter, containing box, and, sometimes, wire. You can purchase components separately from an electrical supply store, but it’s a bigger hassle than it’s worth. If unfamiliar with electrical component assembly and reading wiring diagrams, purchase the assembled ballast in a package containing the lamp and hood from one of the many HID distributors.

Do not buy used parts from a junkyard or try to use a ballast if unsure of its capacity. Just because a bulb fits a socket attached to a ballast, does not mean that it is a proper system. One of the most miserable gardens I have ever seen was grown with mercury vapor streetlights and makeshift reflective hoods. The grower was low on money, so he pilfered all the street lamps, ballast and all, in front of his house.

Even though HIDs have specific ballasting requirements, the ballasts have a good deal in common.The most common characteristics ballasts share are noise and heat. This noise could drive some people to great fits of paranoia! Ballasts operate at 90-150F. Touch a “strike anywhere” kitchen match to the side to check if its too hot. If the match lights, the ballast is too hot and should be taken int shop for assessment. A ballast that runs too hot is noisy and could cause problems or burn out. Heat is the number one ballast destroyer. Many ballasts are manufactured with a protective metal box. This outer shell safely contains the core, capacitor, and wiring. If you build another box around the ballast to dampen noise, make sure there is plenty of air circulation. If the ballast runs too hot, it will be inefficient, burn out prematurely, and maybe even start a fire!

More expensive ballasts are equipped with ventilation fans to maintain col operating temperatures. Air vents allow a ballast to run cooler. The vents should protect the internal parts and prevent water from splashing in.

Some industrial ballasts are sealed in fiberglass or similar material to make the waterproof. These ballasts are not recommended. They were designed fr outdoor use where heat buildup is not a problem. Indoors, the protection of the sealed unit from weather is unnecessary and creates excessive heat and inefficient operation.

A handle will make the ballast easy to move. A small 400-watt halide ballast weighs about 30 pounds, and a large 1000-watt HP sodium ballast tips the scales at about 55 pounds. This small, heavy box is awkward to move without a handle.

Most ballasts sold by HID stores are “singe tap” and setup for 120 volt household current in North America or 240 volts in Europe, Australia, and New Zealand. North American ballasts run at 60 cycles per minute, while European, Australian, and New Zealand models run at 50 cycles per minute. A ballast from Europe, Australia, or New Zealand will not work properly at 60 cycles per minute. Some “multi-tap” or “quad-tap” ballasts are ready for 120 or 240 volt service. Single-tap ballasts accommodate only one voltage, usually 120. Multi-tap ballasts accommodate either 120 or 240 volt service.

It is generally easiest to use the regular 120-volt systems, because their outlets are more common. the 240-volt systems are normally used in Europe, Australia, and New Zealand or in North America with several lamps are already taking up space on other 120-vlt circuits. Changing a “multi-tap” ballast from 120 volts to 240 volts is a simple matter of moving the wire from the 120 volt tap to the 240-vlt tap. “Singe tap” ballasts cannot change operating voltages. Consult the wiring diagram found on each transformer for specific instructions. The is no difference in the electricity consumed by using either 120 or 240 volt systems.

The ballast has a lot of electricity flowing through it. Do not touch the ballast when operating. Do not place the ballast directly on a damp floor or any floor that might get wet and conduct electricity. Always pace it up ff the floor, and protect it from possible moisture. The ballast should be suspended in the air or on a shelf attached to the wall. It does not have to be very high off the ground, just far enough t keep it dry.

Place the ballast on a soft foam pad to absorb vibrations and lower decibel sound output. Loose components inside the ballast can be tightened to further deaden noise cause by vibrations. Train a fan on ballasts to col them. Cooler ballasts are more efficient, and bulbs burn brighter.

Ballasts can be attached to the light fixture remote. The remote ballast offers the most versatility and is the best choice for most indoor grow shows. A remote ballast is easy t move. Help control heat by placing it on or near the floor to radiate heat in a col portion of the grow room, or move the ballast outside the garden t cool the room. Attached ballasts are fixed to the hood; they require more overhead space, are very heavy, and tend to create more heat around the amp.

Ballasts may be manufactured with an attached timer. These units are very convenient, but the time should be constructed of heavy duty heat resistant materials. if it is lightweight plastic, it could easily met under the heat of the ballast.

Ballasts with a switch allow growers t use the same ballast with two different sets of lights. This wonderful invention is perfect for running two flowering grow rooms. The lights go on for 12 hours in one grow room while they are off in in a second room. When the lights turn off in the first room, the same ballasts hooked to another set of lights in the second room are turned on. This setup is very popular in Canada.

There are also ballasts to run both metal halide and HP sodium systems. These dual-purpose ballasts are not a good idea. They will work, but they generally over-drive the metal halide bulb causing it to burn out prematurely after accelerated lumen output loss. I do not recommend these types of ballasts. If you have a limited budget and can only afford one transformer, use conversion bulbs to change spectrum.

HID Bulbs

Many new HID bulbs have been developed in the last few years. The most notable have been the 430-watt HP sodium, pulse start metal halides, the AgroSun, SunMaster PAR bulbs, and the 1100-watt metal halide. These HID bulbs are also available with many different outer envelopes, so bulbs can fit into more confining reflective hoods.

High intensity discharge bulbs are rated by wattage and by the size of the outer envelope or bulb. HID bulbs come in different shapes and sizes. Below each bulb are the numbers industry uses to define their shape and size.

In general, HID bulbs are designed to be tough and durable. New bulbs are tougher than used bulbs. Once the bulb has been used for a few hours, the arc tube blackens, and the internal parts become somewhat brittle. After a bulb has been used several hundred hours, a good bump will substantially shorten its life and lessen luminescence.

Never remove a warm lamp. Heat expands the metal mogul base within the socket. A hot bulb is more difficult to remove, and it must be forced. Special electrical grease is available to lubricate sockets (Vaseline works too). Lightly smear a dash of lubricant around the mogul socket base to facilitate bulb insertion and extraction.

Always keep the bulb clean. Wait for it to cool before wiping it off with a clean cloth every two to four weeks. Dirt will lower lumen output substantially. Bulbs get covered with insect spray and salty water vapor residues. This dirt dulls lamp brilliance just as clouds dull natural sunlight.

Hands off bulbs! Touching bulbs leaves them with your hands oily residue. The residue weakens the bulb when it is baked onto it. Most growers clean bulbs with Windex or rubbing alcohol and use clean cloth to remove filth and grime, but Hortilux Lighting advises cleaning bulbs with a clean cloth only.

Lumen output diminishes over time. As the bulb loses brilliance, it generates less heat and can be moved closer to the garden. This is not an excuse to use old bulbs; it is always better to use newer bulbs. However, it is a way t a few more months out of an otherwise worthless bulb.

Write down the day, month, and year you start using a bulb so you can better calculate when to replace it for best results. Replace metal halides after 12 months of operation and HP sodium bulbs after 18 months. Many growers replace them sooner. Always keep a spare bulb in its original box available to replace old bulbs. You can go blind staring at a dim bulb trying to decide when to replace it. Remember, your pupils pen and close to compensate for different light levels. one way to determine when to replace a bulb is to examine the arc tube. When the arc tube is very cloudy or very blackened, it is most likely time to replace it.

Metal Halide Systems

The metal halide HID lamp is the most efficient source of artificial white light available to growers today. It comes in 175, 250, 400, 1000, 1100, and 1500-watt sizes. They may be either clear or phosphor coated, and all require a special ballast. The smaller 175 or 250-watt halides are very popular for closet grow rooms. The 400, 1000, and 1100-watt bulbs are very popular with most indoor growers. The 1500-watt halide is avoided due to its relatively short 2000 to 3000 hour life and incredible heat output. American growers generally prefer the larger 1000-watt lamps, and Europeans almost exclusively favor 400-watt metal halide lamps.

The main metal halide manufacturers include General Electric (Multivapor), Osram / Sylvania (Metalarc) and Westinghouse (Metal Halide), Iwasaki (Eye), Venture (SunMaster), and Philips (Son Agro). Each manufacturer makes a super halide which fits and operates in standard halide ballasts and fixtures. Super metal halide produce about 15 percent more lumens than standard halides. Super halides cost a few dollars more than standards but are well worth the money.

SunMaster, a division of Venture Lighting, has developed new horticultural metal halide bulbs. The new bulbs are brighter and provide a spectrum better suited to plant growth. Growers prefer the Warm Deluxe bulbs.

Clear halides are most commonly used by indoor growers. Clear super meta halides supply the bright lumens for plant growth. Clear halides work well fr seedling, vegetative, and flower growth.

Phosphor coated 1000-watt halides give off a more diffused light and are easy on the eyes, emitting less ultraviolet light than the clear halides. They produce the same initial lumens and about 4000 fewer lumens than the standard halide and have a slightly different color spectrum. Phosphor coated halides have more yellow, less blue and ultraviolet light. Phosphor coated bulbs used t be popular among growers, but this trend has waned over the last ten years because they are not as bright as clear bulbs.

The 1000-watt super clear halides are the most common halides used to grow marijuana in North America. Compare energy distribution charts and lumen output of all lamps t decide which amp offers the most light for your garden. Typically, a home grower starts with one super metal halide.

Construction and Operation

Metal halide lamps produce light by passing or arcing electricity through vaporized argon gas, mercury, thorium iodide, sodium iodide, and scandium iode within the quartz arc tube. After they are in their proper concentrations in the arc tube, the characteristic bright white light is emitted. This process takes about three to five minutes. The metal halide arc system is very complex and requires a seasoning period of 100 hours operation for all of its components to stabilize. If a power surge occurs and the lamp goes out or is turned off, it will take five to fifteen minutes for the gases inside the arc tube t cool before restarting.

The outer bulb functions as a protective jacket that contains the arc tube and starting mechanism, keeping them in a constant environment as well as absorbing ultraviolet radiation. Protective glasses that filter out ultraviolet rays are a good idea if you spend much time in the grow room, or if you are prone to staring at the HID!

When the lamp is started, incredible voltage is necessary for the initial ionization process to take place. Turning the lamps n and off more than once a day causes unnecessary stress on the HID system and will shorten its life. It is best to start the amp only once a day, and always use a timer.

The metal halides operate most efficiently in a vertical +- 15 degree position. When operated in positions other than +- 15 degrees of vertical, lamp wattage, lumen output, and life decrease; the arc bends, creating non-uniform heating of the arc tube wall, resulting in less efficient operation and shorter life. There are several lamps made to operate in the horizontal or any other position. These bulbs have “HOR” stamped on the crown or base which refers to horizontal.

Lumen Maintenance and Life

The average life of a halide is about 12,000 hours, almost two years of daily operation at 18 hours per day. Many will last even longer. The amp reaches the end of its life when it fails to start or come up to full brilliance. This is usually caused by deterioration of lamp electrodes over time, loss of transmission of the arc tube from blackening, or shifts in the chemical balance of the metals in the arc tube. Do not wait until the bulb is burned out before changing it. An old bulb is inefficient and costly. Replace bulbs every 10-12 months or 5000 hours. Electrode deterioration is greatest during start up. Bulbs are cheap! Throw another one in, and you will be happy!

The halide may produce a stroboscopic (flashing) effect. The light will appear bright, then dim, bright, dim, etc. This flashing is the result of the arc being extinguished 120 times every second. Illumination usually remains constant, but it may pulsate a little. This is normal and nothing to worry about.

Meta Halide Ballasts

The ballast for 1000-watt halide will operated standard, clear, and phosphor-coated and super, clear, and phosphor-coated halides on a 120 or 240 volt current. Different ballast are required for each amp wattage. The ballast for each wattage will operate all halides f the same wattage. Each ballast must be specifically designed fr 150, 250, 400, 1000, 1100, or 1500-watt halides, because their starting and operating requirements are unique.

Metal Halide Bulbs

Universal metal halide bulbs designed to operate in any position, vertical or horizontal, supply up to ten percent less light and often have a shorter life.

SunMaster Warm Deluxe Grow Lamps emit balanced light similar to a 3000 Kelvin source. The enhanced orange-red component promotes flowering, stem elongation, and germination while a rich blue content assures healthy vegetative growth.

Venture manufactures the AgroSun for Hydrofarm. It is an enhanced metal halide bulb with more yellow / orange in the spectrum.

High Pressure Sodium Systems

The most impressive fact about the 600-watt high pressure sodium lamp is that it produces 90,000 initial lumens. The HP sodium is also the most efficient HID lamp available. It comes in 35, 50, 70, 100, 150, 200, 250, 310, 400, 600, and 1000-wattages. Nearly all of the HP sodium bulbs used in grow rooms are clear. All HP sodium vapor lamps have their own unique ballast. High pressure sodium lamps are manufactured by GE (Lucalox), Syvania (Lumalux), Westinghouse (Ceramalux), Philips (SonAgro), Iwasaki (Eye), and Venture (High Pressure Sodium). American growers use 1000 and 600-watt HP sodiums most often, while European growers love 400 and 600 watt HPS lamps.

High pressure sodium lamps emit an range tinged glow that could be compared to the harvest sun. The color spectrum is highest in the yellow, range, and red end. For many years, scientists believed this spectrum promoted flower production. However, with the new PAR technology, scientists are rethinking old theories. Marijuana’s light needs change when flowering; it no longer needs to produce so many vegetative cells. Vegetative growth slows and eventually stops during blooming. All the plants’ energy and attention is focused on flower production so it can complete its annual life cycle. Light from the red end of the spectrum stimulates floral hormones within the plant, promoting flower production. According to some growers, flower volume and weight increase when suing HP sodium lights. Other compelling evidence shows that the SunMaster halides to be superior. Growers using a 10 x 10 foot room often retain the 1000-watt halide and add a 1000-watt sodium during flowering. Flowering plants need more light to produce tight, full, buds. Adding an HP sodium lamp not only double available light, it increases the red end of the spectrum. This 1:1 ratio (1 halide and 1 HP sodium) is a popular combination for flowering.

Operation and Construction

High pressure sodium lamps produce light by passing electricity through vaporized sodium and mercury within an arc tube. The HP sodium lamp is totally different from the metal halide in its physical, electrical, and color spectrum characteristics. An electronic starter works with the magnetic component of the ballast to supply a short, high voltage pulse. This electrical pulse vaporizes the xenon gas and initiates the starting process that takes three to four minutes. Electricity passes, or arcs, between the two main electrodes. If the amp is turned off, r power surge occurs and the lamp goes out, the gases in the tube will usually need to cool three to fifteen minutes before restarting if possible.

Similar to the metal halide, the HP sodium has a two-bulb construction, with an outer protective bulb and inner arc tube. The outer bulb, or jacket, protects the arc tube from damage and contains a vacuum, reducing heat loss from the arc tube. The sodium, mercury, and xenon gas are contained within the arc tube and have a constant operating temperature. The lamp may be operated in any position (360 degrees). However, most prefer to hang the amp overhead in a horizontal operating position.

Life and Lumen Maintenance

High pressure sodium lamps have the longest life and best lumen maintenance of all HIDs. Eventually, the sodium bleeds out through the arc tube. Over a long period of daily use, the sodium to mercury ratio changes, causing the voltage in the arc to rise. Finally, the arc tube’s operating voltage will rise higher than the ballast is able to sustain. At this point, the lamp will start, warm up to full intensity, and go out. This sequence is then repeated over and over, signaling the end of the lamp’s life. The life of a 1000-watt HP sodium lamp will be about 24,000 hours, or five years, operating at 12 hours per day. Replace HPS bubs after 18 to 24 months to keep the garden bright.

HP Sodium Ballasts

A special ballasts is specifically required for each wattage of HP sodium lamp. Each wattage lamp has unique operating wattages and currents during start-up and operation. These voltages and currents do not correspond to similar wattages of other HID lamps. Sodium ballasts contain a transformer that is larger than that of a metal halide, a capacitor, and an igniter or starter. Purchase complete HID systems rather than a component kit.

HP Sodium Bulbs

High pressure sodium bulbs are used for industrial, residential, and horticultural lighting. The bulbs are inexpensive and readily available. Discount building stores often carry 250 and 400 watt lamps. Al HP sodium lamps will grow cannabis. Even though they are brighter, the spectrum contains little blue, and more yellow / orange. Lack f color balance makes plants stretch between internodes, but does not necessarily diminish overall harvest.

Philips designed and manufactures the 430-watt Son Agro specifically t augment natural sunlight and grow plants. The bulb produces a little more blue light in the spectrum. Adding a touch more blue light helps prevent most plants from becoming leggy. The other enhanced performance HP sodium bulb is the Hortilux by Eye (Iwasaki).

The 600-watt HP sodium increased the lumens-per-watt efficiency of high intensity bulbs by seven percent. The 600-watt HP sodium is the most efficient lamp on the market. The 430-watt Son Agro HP sodium bulbs have more blue in the spectrum and run a little hotter than their 400-watt counterpart. The Son Agro bulbs are the choice of European growers.

Conversion Bulbs

Conversion, or retrofit, bulbs increase flexibility. One type of conversion bulb allows you t utilize a metal halide (or mercury vapor) system with a bulb that emits light similar to an HP sodium bulb. The bulb looks like a blend between a metal halide and an HP sodium. While the outer bulb looks like a metal halide, the inner arc tube is similar to that of an HP sodium. A small igniter is located at the base of the bulb. Other conversion bulbs retrofit HP sodium systems to convert them into virtual metal halide systems.

Conversion bulbs are manufactured in 150, 215, 360, 400, 880, 940, and 1000-watt sizes. You do not need an adapter or any additional equipment. Simply screw the bulb into a compatible ballast of comparable wattage. Conversion bulbs operate at a lower wattage and are not as bright as HP sodium bulbs. Although conversion lamps have less blue, they are up to 25 percent brighter than metal halide systems and their lumens-per-watt conversion is better than that of super metal halides. The 940-watt conversion bulb has a lumens-per-watt rating of 138. Similar to the HP sodium lamp, the conversion bulb has a life expectancy of up to 24,000 hours. Unlike most high pressure sodium lamps which flicker on and off near the end of their lives, conversion bulbs go off and remain off at the end of their lives.

Although conversion bulbs are not inexpensive, they are certainly less expensive than an entire HP sodium system. For gardeners who own a metal halide system, or who deem metal halide the most appropriate investment for their lighting needs, conversion bulbs offer a welcome alternative for bright light. In the United States, CEW Lighting distributes Iwasaki lights. Look fr their Sunlux Super Ace and Sunlux Ultra Ace lamps.

Venture, Iwasaki, and Sunlight Supply manufacture bulbs for conversion in the opposite direction, from high pressure sodium lights to metal halide. Venture’s White-Lux and Iwasaki’s White Ace are metal halide lamps which will operate in an HP sodium system. The 250, 400, 1000-watt conversion bulbs can be used in compatible HPS systems with no alterations or additional equipment. If you own a high pressure sodium system but need the added blue light which metal halide bulbs produce, these conversion bulbs will suit your needs.

Many gardeners have great success using conversion bulbs. If you have a metal halide system but want the extra red and yellow light of an HP sodium lamp to promote flowering, simply buy a conversion bulb. Instead of investing in both a metal halide and an HP sodium system, you can rely on a metal halide system and use conversion bulbs when necessary, or vice versa.

HP Sodium to Metal Halide

The Sunlux Super Ace and Ultra Ace (Iwasaki) and Retrolux (Philips) produce an HP sodium spectrum with a metal halide system. These bulbs make it possible to use a metal halide ballast and get the same spectrum as an HP sodium lamp. Lumens-per-watt efficiency is traded for the convenience of using these bulbs. A 1000-watt HP sodium bulb produces 140,000 initial lumens. A MH to HPS conversion bulb produces 130,000 initial lumens. If you only want one lamp, a conversion bulb is a fair choice.

Metal Halide to HP Sodium

The White Ace (Iwasaki) and White Lux (Venture) are conversion bulbs. They have a metal halide spectrum and are used in an HPS system. The bulb converts from HPS to MH and produces 110,000 initial metal halide lumens.

Mercury Vapor Lamps

The mercury vapor lamp is the oldest and best known member of the HID family. The HID principle was first used with the mercury vapor lamp around the turn of the 20th century, but it was not until the mid 1930s that the mercury vapor lamp was really employed commercially.

Mercury vapor lamps produce only 60 lumens per watt. A comparison of the spectral energy distribution of the mercury vapor and the photosynthetic response chart will show this is a poor lamp for horticulture. It is expensive to operate and produces a spectrum with a low PAR value.

amps are available in sizes from 40 to 1000 watts. Bulbs have fair lumen maintenance and a relatively long life. Most wattages last up to three years at 18 hours of daily operation.

Bulbs usually require separate ballasts, however, there are few low wattage bulbs with self contained ballasts. Uninformed growers occasionally try to scrounge mercury vapor ballasts from junk yards and use them in place of the proper halide or HP sodium ballast. Trying to modify these ballasts for use with other HIDs will cause problems.

Fluorescent Lamps

Fluorescent lamps have gone through major changes in recent years. New bulbs produce more light. Most growers use fluorescents to grow clones and small vegetative plants and maintain mother plants. Some growers even use them t flower a crop. Fluorescents are available in many different spectrums, some almost identical t natural sunlight.

Flurescent lamps are long glass tubes that come in a wide variety f lengths, from one to twelve feet. The two- and four-foot tubes are the easiest to handle and most readily available. Two four-foot fluorescent bulbs in a shop light fixture cost from $20 to $30.

Fluorescent lamps work very well for root cuttings. They supply col, diffused light in the proper color spectrum to promote root growth. Use any daylight spectrum fluorescent lamp to root cuttings. Fluorescents produce much less light than HIDs and must be very close (two to four inches) to the plants for best results.

Using fluorescents along with HIDs is awkward and problematic. When using them in conjunction with HIDs, fluorescents must be very close to plants to provide enough intense light to do any good. Fixtures may also shade plants from HID light and generally get in the way.

Plants will flower under fluorescent lights. The buds will be small and light, but, with enough fluorescent light, you can grow a mature crop. The grow show will have to literally be lined with fluorescents.

Fluorescent tubes are available in so many different wattages or outputs that they are hard to track! All fluorescents require specific ballasts. The old standard (T12) tubes use about 10 watts per linear foot. A two-foot tube uses about 20 watts, fur-foot: 40 watts, etc. The most common bulbs used for growing are available in lengths from 15 inches to four feet. lamps are available in very low to more than 50 watts. Circular fluorescent tubes are available but used by a few growers.

Power twist, or groove type, lamps offer additional lumens in the same amount of linear space. The deep wide grooves give more glass surface area and more light output. Several companies market variations of power twist fluorescents.

Black light fluorescent lamps emit ultraviolet (UV) rays through a dark filter glass bulb, but they are not used to grow cannabis. Ultraviolet light is supposed to promote more resin formation on the buds. However, all known experiments that add artificial UV light in a controlled environment have proven that it does not make any difference.

Most of the major lighting manufacturers – GE, Osram / Sylvania, and Philips – make fluorescent lamps in a variety of spectrums. The most common are Warm White, White, Cool White, Full Spectrum, and Daylight. Sylvania has the Growlux and the Wide Spectrum GroLux. The Standard GroLux is the lamp to use for starting clones or seedlings. It is designed for use as the only light source, having the full spectrum necessary for photosynthesis and chlorophyll production. The Wide Spectrum GroLux is designed to supplement natural light and covers the blue to far-red regions. Westinghouse has the AgroLight that produces a very similar spectrum to the sun. Warm White and Cool White bulbs used together make excellent lamps to root clones.

Fluorescent bulbs are further classified by diameter and come in the sizes T12 (1.5 inch), T8 (1 inch), T5 (0.625 inch), and CFL. The T12 uses old fashioned magnetic ballasts. The T8 and the T5 (technically CFLs) use electronic ballasts. Growers prefer slimmer T8 and T5 bulbs with electronic ballasts because they run cooler, electricity cycles faster, and lights do not flicker.

Construction and Operation

Fluorescent lamps create light by passing electricity through gaseous vapor under low pressure. Like the HID family, fluorescents require an appropriate fixture containing a small ballast to regulate electricity and household electrical current. The fixture is usually integrated into the reflective hood. There are several types of fixtures. The most common fluorescent bulbs used for growing are hooked to sockets with bi-pin connectors. If purchasing new tubes, make sure the bulb fits the fixture. The fixture may contain one, two, or fur tubes.

A ballast radiates almost all heat produced by the system. The ballast is located far enough away from the fluorescent tubes that plants can actually touch them without being burned.

Ballasts will normally last 10-12 years. Used fluorescent fixtures are generally acceptable. The end of a magnetic ballast’s life is usually accompanied by smoke and a miserable chemical odor. Electronic ballasts simply stop. When the ballast burns out, remove it and buy a new one to replace it. Be very careful if the ballast has brown slime r sludge on or around it. This sludge can contain carcinogenic PCBs. If the ballast contains the sludge, dispose of it in an approved location. Most modern fluorescents are self starting, but older fluorescents require a special starter. This starter may be integrated into the body of the fixture and hidden from view, or be a small metal tube, located at the end of the fixture on the underside. The latter starters are replaceable, while the former require a trip to the electrical store.

If your fluorescent fixture does not work, and you are not well versed in fluorescent troubleshooting, take it to the nearest electric store and ask for advice. Make sure they test each component and tell you why it should be replaced. It might be less expensive to buy a new fixture.

The tubular glass bulb is coated on the inside with phosphor. The mix f phosphorescent chemicals in the coating and the gases contained within determine the spectrum of colors emitted by the lamp. Electricity arcs between the two electrodes located at each end of the tube, stimulating the phosphor to emit light energy. The light emission is strongest near the center of the tube and somewhat less at the ends. If rooting just a few cuttings, place them under the center of the fixture for best results.

Once the fluorescent is turned on, it will take a few seconds for the bulb to warm up before an arc can be struck through the tube. Fluorescents blacken with age, losing intensity. Replace bulbs when they reach 70 percent of their stated service life listed on the package or label. A flickering light is about to burn out and should be replaced. Life expectancy ranges from 9000 hours (15 months at 18 hours daily operation).

Compact Fluorescent Lamps

Available since the early 1990s, compact fluorescent lamps (CFL) are finally available in larger wattages. The larger CFLs are having a major impact on small indoor grow shows. CFLs are similar to long tube fluorescents but boast increased power, smaller size, and an electronic ballast that ensures longevity and precise spectrum rendition. Although not as bright as HIDs, they are available in Col White and Warm White spectrums and generate little heat. Compact fluorescent lamps are perfect for growers with a limited budget and a small space. They run cooler than HIDs and require minimal ventilation.

When CFLs were first introduced, wattages were too small, and bulbs did not emit enough light to grow cannabis. New large-wattage CFLs are much brighter than smaller, low-wattage CFLs. Several years ago, European companies started selling 55-watt CFLs and Home Depot began to sell a 65-watt CF flood light for $30. Soon afterward 95, 125, and 200-watt CF lamps made in China became available in North America and Europe. The new lamps changed the way growers looked at CFLs. The new CFLs provide enough light to grow cannabis from seed to harvest.

Compact fluorescent bulbs used to grow cannabis are available in two basic styles and shapes. Modular CFLs have independent bulbs and ballasts that can be replaced separately. the bulb is shaped like a long “U” with a two- or four-pin fixture. The 20-inch long “1U” 55-watt, dual pin base bulbs are common in Europe. Normally, two 55-watt lamps are placed in a reflective hod. Shorter U-shaped bulbs are common in North America, the United States, and New Zealand.

The second type consists of miniaturized fluorescent tubes packaged with an attached electronic ballast. The short lamps consist of several U-shaped tubes (designated 4U, 5U, 6U, etc, for the number of U-shaped tubes) that measure from eight to twelve inches not including the two to four inch attached ballast and threaded base. Smaller wattages fit into household incandescent light bulb sockets. Larger 95, 125, 150, and 200-watt bulbs require a larger mogul socket. Common wattages used for growing cannabis include 55, 60, 65, 85, 95, 120, 125, 150, and 200.

Light from CFLs fades fast and must be placed close to the plants. The bulb produces very little heat and can be mounted about two inches away from foliage to achieve best results.

Short U-shaped bulbs are most efficient when vertically oriented. When mounted horizontally under a refl3ective hood, much light is reflected back and forth between the bulb’s outer envelope and the hood, which markedly lowers efficiency. heat also builds up from the ballast. Both conditions lessen efficiency.

Save electricity in the grow house and replace incandescent bulbs with compact fluorescents. Compact fluorescents use about 75 percent less energy than incandescent lamps, and emit 90 percent less heat for the same amount light. If you replace ten 100-watt incandescent bulbs, you will save 750 watts f electricity!

Construction and Operation

Compact fluorescent lamps create light by passing electricity through gaseous vapor under low pressure. Compact fluorescent bulbs are coated inside with tri-phosphor which further expands light emission. CFLs must warm up about five minutes so the chemicals become stable before they come to full brightness. Like all fluorescents, CFLs require an appropriate fixture containing a small electronic ballast to regulate electricity and household electrical current. Ballasts are either attached to the lamp or integrated into the reflective hood. Smaller self-ballasted lamps screw into a household incandescent bulb socket. larger bulbs screw into a mogul socket. Each 1-U bulb is hooked to sockets with bi-pin connectors.

Compact fluorescent lamps will normally last 10-20,000 hours (18-36 months at 18-hour daily use). The life of a CF ballast is from 50,000 to 60,000 hours (seven to nine years at 18 hours daily use). Lamps with an attached ballast burn out three to six times faster than the ballast. When the lamp’s life is over, the lamp and the attached ballast are both thrown away, which means you are throwing away a perfectly good ballast! My preference is to use the long CFLs that are not attached to a ballast.

Compact fluorescent lamps can also be used to supplement the reddish-yellow spectrum from HP sodium lamps. However, the outer case covering the attached ballast is susceptible to deterioration from UV light. When used in conjunction with other HID lamps that produce UV rays, the ballast case deteriorates more quickly. Attached ballasts are not designed for humid grow room application. Couple this weakness to humidity with a bit of UV light, and bulbs burn out more quickly. The end of a ballast life is signaled when it stops. When the ballast burns out, remove and replace it.

Although CFLs are not considered hazardous waste, they still contain a little mercury and should be disposed of properly to avoid contaminating the environment. Place CFL bulbs in a sealed plastic bag and dispose the same way you do batteries, oil based paint, motor oil, etc., at your local Household Hazardous Waste (HHW) Collection Site.

Other Lamps

Several other lamps deserve a mention, however, they grow marijuana poorly. Incandescent amps are inefficient, tungsten halogen lamps are bright but inefficient, and low pressure sodium lamps are efficient but have a limited spectrum.

Incandescent Lamps

Incandescent lamps were invented by Thomas Edison. Light is produced by sending electricity through the filament, a super fine wire inside the bulb. The filament resists the flow of electricity, heating it to incandescence, causing it to glow and emit light. The incandescent bulbs work on ordinary home current and require no ballast. They come in a wide range of wattages and constructions.

Most incandescent lamps have a spectrum in the far red end, but there are some incandescent grow lamps that have enhanced blue spectrum. They are expensive to operate and produce few lumens-per-watt. They are most efficiently used as a source of rooting medium heat for clones rooting under col fluorescents.

Tungsten Halogen Lamps

The tungsten halogen lamp is a poor grow light. It was originally called Iodine Quartz lamp. The outer tube is made of heat-resistant quartz. the main gas inside the quartz tube was iodine, one of the five halogens. Today, Bromine is used most often in the lamps. Similar to incandescent lamps, they use a tungsten wire filament and a sealed bub are are very expensive to operate. Their lumen-per-watt output is very low. They run on a household current and require no ballast. Tungsten bulbs are inefficient to operate as are the incandescent lamps. Their color spectrum is in the far-red end with 10-15 percent in the visible spectrum.

LP Sodium Lamps

Low Pressure sodium lamps are monochromatic. Do not use these amps to grow cannabis. They produce light in a very narrow portion f the spectrum, at 589 nanometers, and emit a yellow glow. They are available in wattages from 55 to 180. Their lumens-per-watt conversion is the highest of all lamps on the market today. Their main use in industry has been for security or warehouse light.

Lamps require specific ballasts and fixtures according to wattage. The fixture for a 180-watt lamp is just a little larger than a fixture for two 40-watt, four-foot fluorescent tubes.

Electricity & Safety

You don’t need to understand the basics of electricity to grow indoors or in a greenhouse, but understanding the basics will save you money, time, and possibly the shock of your life.

Before you touch anything electrical, please remember to work backwards when installing electrical components or doing wiring. Start at the bulb, and work towards the plug-in. Always plug in the cord last!

Ampere (amp) – is the measure of electricity in motion. Electricity can be looked at in absolute terms of measurement just as water can. A gallon is an absolute measure of a portion of water; a coulcomb is an absolute measure of a portion of electricity. Water in motion is measured in gallons per second, and electricity in motion is measured in coulombs per second. When an electrical current flows at one coulomb per second, we say it has one ampere.

Breaker Switch – ON / OFF safety switch that will turn electricity OFF when the circuit is overloaded. Look for breaker switches in the breaker panel or breaker box.

Circuit – the circular path that electricity travels. if this path is interrupted, the power will go off. If this circuit is given a chance, it will travel a circular route through your body!

Conductor – something that is able to carry electricity easily. Copper, steel, water, and your body are good electrical conductors.

Fuse – Electrical safety device consisting of a fusible metal that melts and interrupts the circuit when overloaded. Never replace fuses with pennies or aluminum foil! They will not melt and interrupt the circuit when overloaded. This is an easy way t start a fire.

Ground – means to connect electricity to the ground or earth for safety. If a circuit is properly grounded and the electricity travels somewhere it is not supposed to, it will go via the ground wire into the ground and be rendered harmless. Electricity will travel the path f least resistance. This path must be along the ground wire.

The ground is formed by a wire (usually green, brown, or bare copper) that runs parallel to the circuit and is attached to a metal ground stake. Metal water and sewer pipes also serve as excellent conductors for the ground. Water pipes conduct electricity well and are all in good contact with the ground. The entire system, pipes, copper wire, and metal ground stake conduct any misplaced electricity safely into the ground.

The ground wire is the third wire with the big round prong. The ground runs through the ballast all the ay t the hod. High intensity discharge systems must have a ground that runs a continual path from the socket through the ballast to the main fuse box, then to the house ground.

GFI – Ground Fault Interrupt outlets are required anywhere water is used in a home or business. Instal GFI outlets in grow rooms to provide an instant, safe, electrical shut off when necessary.

Hertz – Irregular fluctuations or cycles in electricity within a conductor (wire). In the United States, electricity runs at 60 hertz (Hz), or cycles, per second.

Ohm’s Power Law – a law that expresses the strength of an electric current: colts x amperes = watts.

Short Circuit – A short or unintentional circuit formed when conductors (wires) cross. A short circuit will normally blow fuses and turn off breaker witches.

Volts – Electricity is under pressure or electrical potential. This pressure is measured in volts. Most home wiring is under the pressure of approximately 120 or 240 volts.

Watts – are a measure of work. Watts measure the amount of electricity flowering in a wire. When amperes, (units of electricity per second) are multiplied by volts (pressure), we get watts. 1000 watts = 1 kilowatt.

A halide lamp that draws about 9.2 amperes x 120 volts = 1104 watts. Remember Ohm’s Power Law: amps x watts = volts. This is strange; the answer was supposed to be 1000 watts. What is wrong? The electricity flows through the ballast, which uses energy to run. The energy drawn by the ballast must amount to 104 watts.

Watt-hours – measure the amount of watts that are used during an hour. One watt-hour is equal to one watt used for one hour. A kilowatt-hour (kWh) is 1000 watt-hours. A 1000-watt HID will use roughly one kilowatt per hour, and the ballast will use about 100 watts. Electrical bills are charged out in kWh.

Electrical wire comes in many thicknesses (gauges) indicated by number. Higher numbers indicate smaller wire and lower numbers indicate larger wire. Most household circuits are connected with 14-gauge wire. Wire thickness is important for two reasons – ampacity and voltage drop. Ampacity is the amount f amperes a wire is able to carry safely. Electricity flowing thru wire creates heat. The more amps flowing, the more heat created. Heat is wasted power. Avoid wasting power by using the proper thickness of well-insulated wire with grounded wire connection.

Using too small of a wire forces too much power through wire, which causes voltage drop. Voltage (pressure) is lost in the wire. A lamp designed to work at 120 volts that only receives 108 volts would produce only 70 percent of the normal light. Use at least 14-gauge wire for any extension cords, and if the cord is to carry power over 60 feet, use 12 gauge wire.

Plugs and outlets must have a solid connection. If they are jostled around and the electricity is allowed to jump, electricity is lost in the form of heat; the prongs will burn, and a fire could result. Periodically check plugs and outlets to ensure they have a slid connection.

If installing a new circuit or breaker box, hire an electrician or purchase Wiring Simplified by H.P. Richter and W.C. Schwan. it costs about $10 and is available at most hardware stores in the USA. Installing a new circuit in a breaker bx is very easy, but installing another fuse in a fuse box is more complex. Before trying anything of this scope, read about it, and discuss it with several professionals.

Electricity Consumption

It is not a crime to use electricity that has been legally purchased. No sensible judge would issue a search warrant on the basis of suspicious electricity consumption. However, not all judges are sensible, and small communities with bored police officers or special marijuana task forces often take it upon themselves to investigate whatever information they are able to weasel out of electric company employees. Larger police forces do not have the desire, time, or money to look for small time marijuana gowers. I once went to check on the electricity consumption of a home I was thinking about renting; I went to the electric company and asked how much electricity the current tenant was using. The electric company employee called up the address on the computer and spun the screen around for me to examine. I could see the electrical consumption for the past few years as well as all the personal information about the tenant! If this is what I can do with a simple question and a smile, imagine what law enforcement officials can do with this information!

There are many ways to deal with the increase in electricity consumption. One friend moved into a home that had all the electric heat and a fireplace. He installed three HID lamps in the basement that also generated heat. The excess heat was dispersed via a vent fan attached to a thermostat / humidistat. He turned off the electric heat, bought a fireplace insert, and started heating with wood. Even running three lamps, consuming three kilowatts per hour, the electric bill was less than it had been with electric heat! Electric bills are controlled with and generated by a computer system. Monthly energy consumption is often displayed n a bar graph for the previous 12 months. This graph makes it easy to see fluctuations in electricity consumption.

A one- to three-bedroom home can run two to three 1000-watt lamps, and a four to five-bedroom home can operate three to five lamps with little or no suspicion regarding electrical consumption. Powering any more lamps usually requires adding new incoming circuit, or the use of present circuits will be severely limited.

The amount of electricity consumption and the size of the home are proportional. often, in increase in electric consumption in normal. For example, electric bills always increase if there is a baby in the home or if there are more residents living there. Changing to gas or wood heat and a gas stove and water heater will also lower the electricity bill.

The electric company might call to ask if you were aware of your increased electricity bill. This is nothing to worry about. Simply reply that you are aware of the electricity being used. If you like to make excuses, some appliances that draw a a lot of electricity are: electric pottery kiln, arc welder, and hot tub. If the situation warrants, take showers at a friend’s house or at a gym, use a Laundromat, and never use any electrical appliances.

The meter reader may think it is strange to see the electric meter spinning like a top during the middle of the day when nobody is home. Change the daylight cycle to be on at night, s the meter reader sees the meter when the lamps are off. Growers tend to know exactly when the meter reader is coming around. Now meter readers are using high tech telescopes to read the dials on the meter and storing the readings in an integrated digital entry device. The information is then dumped into the larger computer at the central office. One friend had his meter replaced by the power company. The company had noticed a major change in electricity consumption at the residence and thought that it could be due to a defective meter, so the meter was changed, but no difference was realized. Large electricity consumers may use a heavy duty commercial power meter.

Some people bypass the meter or figure out some other way to steal electricity. This is a bad idea. If you are stealing electricity from the power company, they might find out. Stealing electricity is a very god way to cal unnecessary attention to your growing operation. If you steal electricity, you are making it easy for someone from the power company to investigate you. Of course, some people have stolen electricity for years and gotten away with it, and they might get away with it forever. Ironically, one of the main reasons that people steal electricity in the first place is because of security. If conspicuous electricity consumption is a problem, a generator will help.


Generators can supply all the electricity necessary for a grow room, and you can grow “off the power grid”. Reliability, ampere output, and noise are important to consider when shopping for a generator.

By the generator new. It should be water cooled and fully automated. Start it up, and check its noise output before purchasing. Always buy a generator that is big enough to do the job. A little extra cushion will be necessary to allow for power surges. If it fails, the crop could fail! Allow about 1300 watts per lamp to be run by the generator. The ballast consumes a few watts as does the wire, etc. A 5500-watt Honda generator will run four lamps.

Honda generators are one of the most common found in grow rooms because they are reasonably priced, dependable, and quiet. But, they are not designed to work for long periods. One grower I met hooked up a generator to a six-cylinder gasoline motor. It could run five amps with ease, but it guzzled a lot of gas. Diesel motors are more economical to run, but noisy, and the toxic fumes reek. Always make sure gasoline or diesel powered generators are vented properly. The exhaust produces carbon monoxide, which is toxic to plants and humans.

Gasoline generator motors can be converted to propane, which burns much cleaner, and the exhaust may be used as a source of CO2.

Diesel generators for truck and train car refrigerators can run many, many lights. Check with wholesale railway and truck wrecking yard outlets for such generators. The generators are usually moved to a below ground location and covered with a building. With a god exhaust system and baffling around the motor, the sound is soon dissipated. Muffling the exhaust and expelling the fumes is a little complex but very effective. The exhaust must be able to escape freely into the atmosphere.

Maintaining a generator that runs 12 hours a day is a lot of work. The generator will need fuel and must be monitored regularly. If the generator shuts down prematurely, plants stop growing.

I once interviewed a grower who ran a generator for six years. He seemed to know a lot about the idiosyncrasies of the machine. He also had the innate feeling that the machine would do something outrageous if he were not there to make it right. This underlying theme dominated the entire interview. Running the generator motor – making sure it had oil, fuel, and ran quietly – was all he thought about when he was growing in the country with “Big Bertha”, who produced 20 kilovolts of electricity.


A timer is an inexpensive investment that turns lights and other appliances on and off at regular intervals. using a timer ensures that your garden will receive a controlled light period of the same duration every day.

Purchase a heavy duty grounded timer with an adequate amperage and tungsten rating to meet your needs. Some timers have a different amperage rating for the switch; it is often lower than that of the timer. Timers that control more than one lamp are more expensive because they require the entire force of electricity to pass through them. many pre-wired timers are available at stores that sell HID lights.

How many lights (total watts) will the timer handle? If you are running more than 2000 or 3000 watts, you may want to attach the lamps to a relay, and control the relay with a timer. The advantage of a relay is that it offers a path for more electricity without having to change the timer. There are numerous sophisticated timers on the market that will solve every last need you have.

Setting up the HID System – Step by Step

Step one – Before setting up the HID system, read “Setting Up the Grow Room” in Chapter Six, and compelte the step-by-step instructions.

Step Two – Both the lamp and the ballast radiate quite a bit of heat. Take care when positioning them, so they are not so close to plants or flammable wallas and ceiling that they become hazardous. If the room has limited space with a low ceiling, place a protective, non-flammable material like metal between the lamp and ceiling to protect from heat. An exhaust fan will be necessary to keep things col. It is most effective to place the remote ballast near the ceiling to keep things cool. Place it outside the room if the room is too hot. When hanging the lamp on the overhead chain or pulley system, make sure electrical cords are unencumbered and not too close to any heat source.

Step Three – Buy and use a good timer t keep the photoperiod consistent. A decent timer costs from $20 to $30 and is worth its weight in buds!

Step Four – To plug in the HID lamp, it will be necessary t find a proper outlet. A 1000-watt HID lamp will use about 9.5 amperes (amps) of electricity on a regular 120-volt house current. A typical home has a fuse box or a breaker box. Each fuse or breaker witch controls an electrical circuit in the home. The fue or breaker switch will be rated for 15, 20, 25, 30, or 40-amp service. Circuits are considered overloaded when more than 80 percent of the amps are being used. The fuse will have its amp rating printed n its face, and the breaker switch will have its amp rating printed on the switch or on the breaker box. To find out which outlets are controlled by a fuse or breaker switch, remove the fuse or turn the breaker switch off. Test each and every outlet in the home to see which ones don’t work. All the outlets that do not work are on the same circuit. When you have found a circuit that has a few or no lights, radios, tvs, stereos, etc, plugged into it, look at the circuit’s amp rating. If it is rated for 15 amps, you can plug one 1000-watt HID into it. A leeway of 5.5 amps is there to cover any power surges. If the circuit is rated for 20 or more amps, it may be used for the 1000-watt HID and a few other low -amp appliances. To find out how many amps are drawn by each appliance, add up the number of total watts they use, and divide it by 120.

Never put a larger fuse in a fuse box than it is rated for. The fuse is the weakest link in the circuit. If a 20-amp fuse is placed into a 150amp circuit, the fuse is able to conduct more electricity than the wiring. This causes wires t burn rather than the fuse. An overloaded circuit may result in a house fire.

Use an extension cord that is at least 14-gauge wire or heavier if the plug will not reach the desired outlet. Thick 14-gauge extension cord is more difficult to find and may have t be constructed. Smaller 16- or 18-gauge cord will not conduct adequate electricity and will heat up, straining the entire system. Cut the 14-gauge extension cord to the exact length. The further electricity travels, the weaker it gets and the more heat it produces, which also strains the system.

Step Five – Always use a three-prong grounded plug. If your home is not equipped with working three-prong grounded outlets, buy a three-prong grounded plug and outlet adapter. Attach the ground wire to a grounded ferrous metal object like a grounded metal pipe or heavy copper wire driven int the earth to form a ground, and screw the ground into the plug-in face. You will be working with water under and around the HID system. Water conducts electricity about as well as the human body.

Step Six – Once the proper circuit is selected, the socket and hood are mounted overhead, and the ballast is in place (but not plugged in), screw the HID bulb finger-tight into the socket. Make sure the bulb is secured in the socket tightly, but not too tight, and make certain there is a good connection. When secure, wipe off all smudges on the bulb to increase brightness.

Step Seven – Plug the three-prong plug into the timer that is in the FF position. Plug the times into the grounded outlet, set the timer at the desired photoperiod, and turn the timer on. Shazam! The ballast will hum; the lamp will flicker and slowly warm up, reaching full brilliance in about five minutes.

Marijuana Horticulture

Leave a Reply

You can use these HTML tags

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>




Instagram Feed