Marijuana Grow Basics by Jorge Cervantes
Growing indoors requires grow gear to supply and control light, air, water, and the growing medium. Below is a simple discussion that will give you basic understanding of the grow gear you will need – what it is and how it works.
Light and Lamps
You will need a light to illuminate your beautiful plants. If you decide to grow in a small space such as a closet or grow cabinet, you can use fluorescent, compact fluorescent (CFL) or HID lights. Fluorescent lamps work well to grow clones, seedlings and small vegetative crops. CFLs can be used to cultivate clones, mothers, and vegetative plants. When CFLs are placed close enough to flowering plants, big tight buds will develop. HID lamps are favored for growing vegetative and flowering plants.
Two 400-watt HID lamps illuminate plants better than a single 1000-watt lamp because they emit light from two different points. These points (bulbs) can be placed closer to plants. A single 1000-watt lamp must be placed 24-36 inches above plants. A 400-watt lamp can be placed from 12-24 inches above the garden. Each foot closer nearly doubles light intensity.
Use fluorescent, CFL, metal halide, or HP sodium bulbs to grow cannabis. Other bulbs – incandescent, tungsten halogen, LP sodium, mercury vapor – have poor spectrums and are not efficient enough to grow cannabis.
Grow clones, seedlings, and vegetative plants with flourescents. Flowering plants develop smaller, less dense buds under fluorescents.
Wattages available: 15-44, in lengths from 18-48 inches.
Brilliance: Fluorescent lamps range from bright to brighter. Their long shape and low lumen output make it necessary to keep tubes 1-2 inches above plants. Brighter T5 and T8 bulbs can be 4-6 inches above plants. New thin bulbs are brighter than larger tubes. Fluorescent bulbs are classified by the diameter of the tube.
Spectrum: Thermodynamic temperature is measured in kelvin (K). The popular color spectrums are from 3000K (warm white), 4200K (cool white), to 5000K (daylight/natural sunlight). Use a combination of warm and cool white bulbs, or one with a spectrum of about 5000K.
Life of bulb: Rated at 20,000-30,000 hours. Most growers replace bulbs after 2 years of operation at 24 hours a day. take lamp and ballast to a specialty recycling center for electronic devices.
CFL (Compact Fluorescent Lamps)
Grow clones, seedlings, and vegetative plants with CFLs. Keep CFLs close to flowering plants so they develop big, tight buds.
Wattages available: 26-200, in lengths from 6-20 inches.
Brilliance: CFLs produce very bright light with relatively low wattage. The best values are 55-65 watt bulbs. these bulbs are bright and inexpensive. Smaller wattages are less bright and very low wattage. Larger wattages are bright but more expensive.
Spectrum: The color spectrum is delivered at 2700K (warm white) to 5000K (cool white) in a selection of bulbs. Warm white CFLs (2700K) have more red in the spectrum and can be used in conjunction with cool white lamps to avoid internodal stretching during flowering.
Life of bulb: Rated t 8000-15,000 hours. Most growers replace bulbs after 1 to 1.5 years of operation at 18 hours per day. Take lamp and ballast to a specialty recycling center for electronic devices.
LED (light-emitting diode) lamps could be the future of indoor plant lighting. These inherently efficient lamps use solid state lighting to illuminate rather than filaments used by incandescent and tungsten halogen bulbs, or gas which is used in HID, fluorescent, and compact fluorescent bulbs. LED lamps consume a fraction of the electricity of HID and fluorescent / CFL lamps and generate very little heat. LED fixtures are rated for regular household current – 120V and 240V. LED light output continues to increase with improved materials and technological advances while maintaining efficiency and reliability associated with solid state equipment. Do not be fooled by old LED lamps that are not as bright as new models. Do not purchase LED lamps with a rating lower than 1 watt per bulb.
Wattages available: LED lamps are rated in milliwatts (mW) and consume much less electricity than fluorescent, CFL, and HID lamps to generate much more light. Currently the most common LEDs used for plant growth consume 1 watt per bulb. Typically clusters of 80-100 bulbs consuming 80-100 watts respectively are placed in a single fixture.
Brilliance: Directional LEDs ensure that all the light produced is pointed downward so that no light fragments off to the side. LEDs from Philips Lumileds Company produce 115 lumens per watt.
Spectrum: The color sprectrum of each bulb is dictated by the semiconducting material composition and condition. The spectrum can range from infrared to ultraviolet and many colors in between. The new LED “grow” lamps combine blue and red bulbs to form the exact spectrum necessary for cannabis growth.
Life of fixture: LED fixtures have a 100-percent-efficient life expectancy of 30,000 hours – about 6 years when operated 12 hours a day, and 3 years when operated 24 hours a day. Beyond 30,000 hours, brilliance fades approximately 30 percent during the following 20,000 hours.
Ballast: Similar to a ballast the power supply that drives LEDs precisely regulates the flow of electricity in milliwatts to the lamps. The solid state low-wattage device generates very little heat because the flow is not impaired. Several fixtures available today include a fan to dissipate heat quickly and efficiently.
Use high intensity discharge (HID) lamps to grow vegetative and flowering marijuana indoors. The two most common HID lamps are metal halide, which have a clear or “white” light spectrum, and high pressure (HP) sodium, which have a yellowish-orange spectrum.
A ballast is required for a metal halide or HP sodium HID lamp. Conventional analog ballasts contain a transformer, capacitor, and connecting wiring. Some HP sodium ballasts have a started. The transformer and capacitor can be attached to the mogul light socket or connected by and electrical cord to a remote ballast. Attached ballasts are connected to the mogul socket and bulb. The ballast generates heat and should be placed outside the grow room. Do not attach ballasts to extension cords, or the voltage will drop and light will dim.
Unlike conventional ballasts, electronic ballasts are lightweight, use less electricity, and produce little or no electricity-wasting heat. Most electronic ballasts can be used with either 120 or 220 volts, either 50 or 60 cycles, and either metal halide or HP sodium lamps. However, they have a relatively high failure rate of about 10 percent on 400-watt, 600-watt, and 1000-watt lamps. Failure rates for smaller wattages are much lower.
Disposal: Take lamp and ballast to a specialty recycling center. Do not dump where they will wind up in a landfill.
Metal Halide Lamps
Grow vegetative and flowering plants efficiently with metal halide bulbs.
Wattages available: 150, 175, 250, 400, 600, 1000, 1100.
Brilliance: There are many different metal halide bulbs. Super bulbs are always brighter than standards. Bulbs are available in many different models. Some bulbs with the same wattage are brighter than others.
Spectrum: Metal halide bulbs are readily available in a spectrum range of 3000, 4000, and 5500 K.
Life of bulb: Rated at 12,000 hours. Most growers replace bulbs after 12 months of operation. Take lamp and ballast to a specialty recycling center.Do not dump where they will wind up in a landfill.
HP Sodium Lamps
HP sodium lamps are mst often used in flowering rooms, but they can also be used to grow vegetative plants. Stems tend to stretch about 10 percent more when using exclusively HP sodium bulbs.
Wattages available: 150, 175, 250, 400, 600, 1000.
Brilliance: HP sodium lamps are more efficient than metal halides at converting electricity to light.
There are many different HP sodium bulbs. Super bulbs are always brighter than standards. Bulbs are available in many different models. Some bulbs with the same wattage are brighter than other models.
Spectrum: The color spectrum of the bulb is limited to the reddish-yellow end of the spectrum. HP sodium bulbs are readily available in a spectrum range of 2100K to 2200K.
Life of a bulb: Rated at 24,000 hours. Most growers replace bulbs after 18-24 months of operation.
A 430-watt Son Agro bulb with more blue in the spectrum is more effective at keeping plants from stretching than if a standard HP sodium were used.
A 600-watt HP sodium lamps is the most efficient HID available.
Most efficiently used to grow vegetative and flowering plants.
Wattages available: 150,215, 360, 400, 880, 940, 1000.
Brilliance: There are two basic types of conversion, or retrofit bulbs: 1. To use a metal halide system with a bulb that emits light similar to an HP sodium bulb. 2. Retrofit HP sodium to convert it into a virtual metal halide system. Conversion bulbs operate at a lower wattage and are not as bright as HP sodium bulbs. Although conversion bulbs have less blue, they are up to 25 percent brighter than metal halide systems and their LPW conversion is better than that of super metal halides.
Spectrum: Conversion bulbs have a similar kelvin temperature to that of their metal halide and HP sodium counterparts.
Life of bulb: Rated at 24,000 hours. Most growers replace bulbs after 18-24 months of operation.
Use an efficient horizontal reflective hood to direct the most light from a bulb toward plants. A good reflective hood provides 10-40 percent more light than an inefficient one. The ideal reflector can be placed close to the garden canopy and will distribute light evenly.
A reflective hood that distributes light evenly – with no bright hot spots – can be placed closer to plants without burning them. When the lamp is closer, the light plants receive is more intense. In addition to reflective walls, the proper reflective hood over the lamp can double the growing area.
Reflective hoods are made from steel sheet metal, aluminum, or even stainless steel. Some hood manufacturers apply (Titanium) white paint in a powder-coating process. The pebble and 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 hoods also scratch easily and create uneven lighting.
Horizontal reflectors direct half the light downward toward plants, requiring only half of the light to be reflected. Selecting an efficient reflective hod will increase the efficiency of your lamp.
Vertical reflective hods with vertical lamps are less efficient than horizontal ones. Reflected light travels farther before being reflected in parabolic or cone-shaped reflective hoods.
Lightweight reflective hoods with pen ends or sides dissipate heat quickly. Extra air flows directly through the hood and around the bulb in open-ended 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.
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 hoods must have enough vents; otherwise, heat buildup in the fixtures causes bulbs to burn out prematurely. Water-cooled and air-cooled lamp fixtures are somewhat popular in hot climates. These lamps run cooler and can be moved closer to plants.
Using no reflective hood is an option. With no reflector, the lamps burns cooler and emits only direct light, The lamps must be suspended between plants to be used most efficiently.
Reflective walls increase the light that plants on the perimeter of the garden receive by up to 10 percent. Paint walls white or hang white plastic Visqueen or reflective Mylar to increase light reflection on the garden’s perimeter. Keep plants within a few inches of reflective walls to maximize reflective efficiency.
Plants that have just entered the flowering room can stay on the perimeter of the garden for a month until the more mature plants directly under lamps have finished flowering. This simple trick can easily increase harvests by 5-10 percent.
A light mover moves lamps 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 closer to plants. Keep plants at least 12 inches away from a lamp on a light mover. The closer a lamp is to plants without burning them, the more light plants receive.
Manually rotate plants so light reaches all the foliage to promote more even development. Use a light mover or put the containers on wheels to make the job easier.
Add a shallow shelf around the perimeter of the garden to use light that is shunted into walls. Use brackets to put up a 4-6 inch wide shelf around the perimeter. The shelf can be built on a slight angle and lined with plastic to form a runoff canal.
Fresh air is necessary in all indoor gardens. It is easy to obtain and inexpensive to maintain. Air ventilation often makes the difference between a heavy harvest and crop failure. Fresh air brings carbon dioxide (CO2) necessary for plant life into the room. A god ventilation system expels CO2-poor air. Air ventilation is also essential to keep temperature and humidity at proper levels for fast plant growth. Both intake and exit vents are essential for adequate airflow in and out of the grow space. A circulation fan is also necessary to keep the air from from stratifying into hot and cold layers inside the room.
install air exit vents in the hottest part of the room – usually the highest point – for passive, silent air venting. The larger the diameter of the exhaust ducts, the more air that moves out. Airflow is usually inadequate with just an air vent. Add an exhaust fan to make the air move faster out the air vent and increase airflow in the room.
A fresh-air intake vent is necessary to create a flow of fresh air into the room. The vent can be in the form of cracks in the grow room walls, a space under the door, or an actual louvered vent. it must allow enough air to enter the grow room so there is an adequate flow of fresh air into the room.
Locate intake vents near the floor so they bring in cooler air. An exhaust fan vented outdoors that pulls new air through the vent usually creates a sufficient flow of air. If passive airflow through the vent is inadequate, attach a fan to draw air into the room.
A slight vacuum inside the room that keeps the door closed generally provides the perfect scenario. The ratio of 1:4 will give the room a little negative pressure and keep the door closed.
Fresh air entering the room should be the same temperature as air within the room so that plants do not suffer temperature stress. Cover the intake vent with fine mesh silkscreen to help exclude pests.
Grow spaces must have an exhaust vent or an extraction fan. The air must change in the room every 1-5 minutes. Air in small grow spaces should change every minute. A vent fan pulls air out of a rom 4 times more efficiently than a fan is able to push it out.
Axial fans are quiet and move air efficiently when properly installed. Attach the fan to a rheostat (fader switch) to control the speed, or to a thermostat. Turn fans down to the point at which they make virtually no noise and will still keep the room a cl 75F during the day and 70F at night.
Exhaust or extraction fans are rated in cubic feet per minute (cfm) or cubic meters per hour or air volume they can move. The fan should be able to replace the air volume (length x width x height = total volume) of the grow room in 1-5 minutes.
An oscillating circulation fan is essential in al grow rooms. Mount circulation fans on walls or the ceiling of the grow room. Mount at least one 12-16 inch oscillating fan for every 400-600 watts of light. Mount the fans far enough away from the plants so that the turbulent air makes leaves flutter a little. Make sure circulation fan is not set in a fixed position and blowing too hard on tender plants. It could cause windburn and dry out plants, especially small seedlings and clones. Remove the outer shroud of fans with plastic propellers to reduce resistance on the motor. This will extend the life of the motor and prevent fires.
Vent fans are usually attached to ducting to direct air out of the grow room. Flexible ducting is easier to use than rigid ducting. Keep the ducting straight and short. Long runs of ducting cause less air to be expelled and at a slower rate. When ducting turns more than 30 degrees, air movement declines and less air exits the other end.
Direct used grow room air out a chimney, roof vent, or window so that it does nt bother neighbors with the telltale smell of a lush marijuana garden.
Air Temperature and Humidity
Use the vent fan, heater, and air conditioner to maintain the proper temeperature and humidity in the grow room. If the grow room contains a heat and air conditioning vent, use it to supply extra heat or cold air, and to aid air circulation.
Keep the temperature about 75F during the day and 60-70F at night in both vegetative and flowering rooms. This is a basic guideline A couple of degrees warmer is OK.
Keep the humidity about 60 percent day and night in the vegetative room. Keep the humidity about 50 percent day and night in the flowering room.
Install a thermostat and /or a humidistat and attach to the vent fan to automatically turn the vent fan on and off to help control temperature.
Install a maximum / minimum thermometer and hygrometer in all grow rooms. For the most accurate temperature readings, install a thermometer near the ceiling, another at the canopy level of plants, and another near the floor. Take temperature readings before lights go on, once in the heat of the day, and 30 minutes after lights go out. Record the temperature and humidity each time and make sure to keep them at the proper levels.
Carbon Dioxide (CO2) Enrichment
Cannabis can use more CO2 than the 0.04 percent (400 ppm) that naturally occurs in the air. By enriching the amount of CO2 to 0.12-0.15 percent (1200-1500 ppm), plants can grow up to 30 percent faster, providing the genetics, light, water, and nutrients are not limiting. CO2 levels above 5000 ppm are not advised for people.
With CO2, plants use nutrients, water, and space at a faster rate. A higher temperature, from 75-80F will help stimulate more rapid metabolism.
CO2 Emitter Systems
CO2 emitter systems produce no toxic gases, heat, or water. They are also precise, metering an exact amount of CO2 into the room from a cylinder of compressed gas.
Buying a complete CO2 emitter system at a hydroponics store is usually the best option for small indoor growers.
When full, a 50-pound steel tank weighs 170 pounds. A full 20-pound steel tank weighs 70 pounds. A full 20-pound aluminum tank weighs about 50 pounds, and a full 35-pound tank weighs 75 pounds. Most suppliers exchange tanks and refill them. the tanks are also safety inspected once a year.
Carbon dioxide is very cold when released, and once in the atmosphere, CO2 is heavier and cooler than air and cascades onto the plants below. A good air circulation system is essential to keep air mixed.
CO2 Generator Systems
CO2 generator systems that burn natural gas or LP (propane) gas to produce CO2 are less expensive to operate than emitter systems, but they produce heat and water as byproducts of the combustion process. Generators use a pilot light with a flow meter and burner enclosed in a protective housing.
Operate the generators manually or synchronize them with a timer to operate with other grow room equipment such as ventilation fans. CO2 is heavier and colder than the ambient air, so you must have good air circulation for even distribution of CO2.
Cannabis has the most pungent fragrance from when it begins to flower through the end of harvest. Before flowering, many strains of growing marijuana have little fragrance that the exhaust fan can carry outdoors discreetly. A good exhaust fan, vented outdoors, is the first step in cannabis odor control and the easiest way to keep the house from reeking of fresh marijuana. neutralize odors with masking agents and charcoal filters. Masking agents are most effective at exhaust exits, hallways, and doors. Charcoal filter actually remove unwanted fragrance from the air before it is expelled from the room.
Essential oils available in several products actually kill odors by creating a neutral atmosphere at the atomic level. Such products are usually available in gel and spray. The deodorizers can be set out in the room, around the house, and near doorways. Other products are designed to be attached to the ventilation ductwork system.
Activated Carbon Filters
Activated charcoal filters absorb odor molecules and other pollutants in the air. They require three things to work properly.
1. Humidity must be below 55 percent. Above 65-70 percent relative humidity, the charcoal absorbs so much moisture that it clogs.
2. Air must move slowly through charcoal filters to extract odors.
3. Use a pre-filter to remove dust, and change it every 60 days.
Do not use activated carbon that is “crushed”. It is less efficient than charcoal pellets.
Clean, balanced water is essential to grow marijuana. Water that tastes good to drink is usually okay for plants. Good water typically has the proper pH (acid to alkaline balance) and EC (electrical conductivity that measures dissolved solids). Bad water must be altered before using. Moving this water to irrigate plants also presents a few interesting challenges to indoor growers.
The pH scale, from 0-14, measures acid-to-alkaline balance. Zero is the most acidic, 7 is neutral, and 14 is most alkaline. Every full-point change in pH signifies a tenfold increase or decrease in acidity r alkalinity. For example, soil or water with a pH of 5 is 10 times more acidic than water or soil with a pH of 6.
Different mediums perform best at different pH levels. Follow manufacturer’s guidelines for pH level, and correct the pH using the manufacturer’s suggested chemicals.
Stabilize the pH of the water before adding fertilizer. Make a correction if readings vary plus/minus one-half point. Deviations in pH levels often affect nutrient solubility.
Use an electronic pH meter to measure water and nutrient solution pH. You can also measure the pH of soil, soilless substrates, and water and nutrient solutions with an electronic pH pen when the substrate is mixed with water.
Fine dolomite lime, a compound of magnesium (Mg) and calcium (Ca), keeps the soil pH stable. Add 1 cup per cubic foot to keep potting soil pH stable.
Hydrated lime is only calcium and water-soluble. Be very careful when using and do not use more than 0.25 cup per cubic foot.
Raise water and nutrient solution pH with calcium carbonate, potassium hydroxide, or sodium hydroxide. Both hydroxides are caustic and require special handling.
Lower water and nutrient solution pH: Phosphoric and nitric acid can be used to lower pH, as can calcium nitrate, but it is less common. Aspirin also lowers the pH. However, hormonal reactions appear to be triggered by aspirin. Some growers report more hermaphrodites when using aspirin to alter the pH.
EC / PPM
Fertilizers (nutrients) carry an electrical current when dissolved in water. Nutrient (salt) concentrations are measured by their ability to conduct electricity through a nutrient solution. Add elemental salts / metals to a solution and electrical conductivity increases proportionately. Simple electronic meters measure this value and interpret it as total. Every salt in a multielement solution has a different conductivity factor.
Electrical conductivity (EC), conductivity factor (CF), and parts per million (ppm) are the scales used to measure overall fertilizer concentration. European, Australian, and New Zealand growers use EC. Some still use CF in parts of Australia and New Zealand.
Nutrient solutions used to grow marijuana generally range between 500 and 2000 ppm. A dissolved solids (DS) measurement indicates how many parts per million (ppm) of dissolved solids exist in a solution. A reading of 1800 ppm means there are 1800 parts of nutrient in one million parts solution, or 1800/1,000,000.
Let 10-20 percent of the nutrient solution drain from the growing medium after each irrigation cycle to help maintain EC stability. The runoff carries away any excess fertilizer salt buildup in the growing medium.
If the raw irrigation water has a reading of more than 300 ppm, or the sodium level is above 50 ppm, or the calcium / magnesium levels make water “hard”, you should use a reverse osmosis device to filter the mineral salts and make “pure” water.
Reverse osmosis (RO) filters are the easiest and most efficient means to clean excess minerals (dissolved solids) from raw water. To use an RO filter, you need a water tap, drain, and reservoir for the “clean” water. About 65-70 percent of the water processed is waste, and 30-35 percent is clean with an EC near 0.
A readily accessible water source saves time and labor. A 4×4 foot garden containing 16 healthy plants in 3-gallon pots needs 10-25 gallons or water per week. Water weighs 8 pounds per gallon. Run a hose to the garden. A lightweight half-inch hose is easy to handle. The hose should have an on/off valve at the outlet. A rigid water wand will save many broken branches while watering in tight quarters.
Drip systems are used in soil or hydroponic gardens. They deliver nutrient solution (stored in a reservoir) on drop at a time or in low volume, via a low-pressure plastic pipe with friction fittings. Water flows down the pipe and out the emitter one drop at a time r at a very slow rate. Three emitters attached to the main hose are either spaghetti tubes or a nozzle dripper actually emitting from the main hose. Drip irrigation kits are available at garden stores and building centers.
Once set up, drip systems reduce watering maintenance. Fertilizer may also be applied easily via the irrigation system.
Marijuana does not like dry or soggy soil. Soil kept too wet drowns the roots, squeezing out oxygen necessary for nutrient absorption. if soil is too dry foliage does not have enough water. Either case causes slow growth and possible fungal attacks. Poor drainage is most often the cause of soggy soil. It is compounded by poor ventilation and high humidity.
You will have to drain much water out of your grow room. Water can go down a drain or be caught an d pumped or carried away. A floor drain is the easiest method but not always practical or available. Catching drain water in a reservoir requires plants to be elevated on a table. Once the drain water is directed back to the drain basin, it can be removed by hand or with a pump.
Leaching soil flushes out excess nutrient salts that build up in the soil. Flushing the bad stuff out of the soil prevents many possible problems. To leach, put a plant into a deep sink, bathtub, or over a bucket, and then water heavily with three times the volume of water as soil in the pot.
Hydroponics stores make their money selling you hydroponic systems. The salespeople are knowledgeable and can tell you a lot about the systems they sell, but they may oversell their products, and you could end up buying things you do not need. When you consider purchasing hydroponics, start out slowly and purchase a system that can be expanded. Most systems require that you measure the pH and EC (ppm) of the nutrient solution as well as turn it on and off automatically, which requires a timer. Other than that, you will not need more fancy instruments and cool gadgets. Get as much experience as possible before investing too heavily.
Growing hydroponically is considered by many to be superior to growing in soil because you can give plants maximum levels of the exact nutrients they need. Precise control of nutrient uptake makes it possible to reap higher yields faster.
To avoid problems, change the nutrient solution in the reservoir every week. Change nutrient solution every two weeks in systems with a large reservoir. You may need to change the nutrient solution more often when plants are in the last stages of flowering because they use more nutrients at that time.
Plants use so much water that nutrient solutions need to be replenished regularly. Water is used at a much faster rate than nutrients. Casually “topping off” the reservoir with pH-balance water will keep the solution relatively balanced for a week or two. Some growers top off the nutrient solution with 500-700 ppm-strength nutrient solution every 2-3 days. Never let the nutrient solution go for more than 4 weeks before draining it and adding fresh solution. Smart growers avoid problems and leach the entire system with weak nutrient solution for an hour or more between changing the reservoir.
Humic and fulvic acids chelate metallic ions, making them readily transportable by water. The (fertilizer) micronutrients – copper, iron, manganese, and zinc – are difficult to dissolve. When mixed in a chelated form, they become readily available for absorption.
Passive hydroponic systems rely on capillary action to transfer the nutrient solution “passively” from the reservoir to the growing medium. The Dutch are masters of passive systems and achieve amazing results. Wick systems have no moving parts. Low initial cost and low maintenance enhance wick systems’ popularity.
Active hydroponic systems “actively” move the nutrient solution, which is usually recovered. Cannabis is a fast-growing plant and very well suited to active hydroponic systems.
Ebb and flow (flood and drain) hydroponic systems are low maintenance and easy to use. Individual plants in pots or rockwool cubes are set on a special growing bed table that can hold 1-4 inches of nutrient solution. Nutrient solution is pumped into the table or growing bed. The rockwool blocs or containers are flooded from the bottom, which pushes the oxygen-poor air out. Once the nutrient solution reaches a set level, and overflow pipe drains the excess to the reservoir. Ebb and flow systems are ideal for growing many short plants in a Sea of Green garden. A Sea of Green garden is comprised of short females growing closely together, imitating a sea of green. Any garden with plants grouped closely together can be considered a sea of green.
In deep water culture (DWC), seedlings and clones are held in net pots full of expanded clay pellets, rockwool, or other growing mediums. These pots are nestled in holes in a lid that covers the reservoir. Roots dangle into the nutrient solution. A submersible pump lifts nutrient solution to where it splashes into the access lid wetting roots. Roots easily absorb nutrients and water from the solution in the oxygenated environment. An air stone pumps in more bubbles of xygen. Gardens are low maintenance and simple by design, and require no timer because the pumps are on 24 hours a day.
Top-feed hydroponic systems meter nutrient solution in specific doses via spaghetti tubing or an emitter placed at the base of individual plants. Aerated nutrient solution flows into the growing medium and is taken up by roots. The runoff nutrient solution is directed back to the reservoir as soon as it drains from the growing medium.
Top-feed systems come in many configurations. Systems with several gallons of growing medium are best for growing large plants that may require support. Small containers are perfect for smaller plants.
Rockwool, gravel, coconut cir, and expanded clay are the most common growing mediums found in top-feed systems. Versatile top-feed systems can be used with individual containers or slabs in individual beds or lined up on tables.
Nutrient film technique (NFT) hydroponic systems are high-performance gardens when fine-tuned. Aerated nutrient solution flows to roots located in gulleys. Seedlings or cuttings with a strong root system are placed on capillary matting located on the bottom in a covered channel. The capillary matting stabilizes nutrient solution flow and holds roots in place. Constantly aerated nutrient solution flows down the channel or gully, over and around the rots and back to the reservoir. irrigation is most often constant, 24 hours a day. Roots receive plenty of oxygen and are able t absorb a maximum of nutrient solution. Proper gulley incline, volume, and flow of nutrient solution are key elements in NFT gardens.
Aeroponic systems use no growing medium and offer the highest performance possible. Roots are suspended in a dark growth chamber with no growing medium. Roots are misted with oxygen-rich nutrient solution at regular intervals. The humidity in the chamber remains at or near 100 percent 24 hours a day. Roots have the maximum potential to absorb nutrient in the presence of air.
nutrient solution reservoirs should be as big as possible and have a lid to reduce evaporation. Gardens use from 5-25 percent of the nutrient solution every day. A large volume of nutrient solution will minimize nutrient imbalances.
Add water as soon as the solution level drops. The reservoir should contain at least 25 percent more nutrient solution than it takes to fill the beds to compensate for daily use and evaporation.
Check the level of the reservoir daily, and replenish if necessary. Use an indelible marker to make a full line and write the number of gallons or liters contained at that point on the inside of the reservoir tank. Use this volume measure when mixing nutrients.
Soil & Soilless mixes
Soil and soilless mixes that look like soil are my favorite growing mediums. They are inexpensive, easy to use, and forgiving. Maybe it is just my prejudice, but as a lifelong gardener, I like t get my hands dirty.
Potting soil fresh out of the bag often fulfills all requirements for a growing medium: texture that allows good root penetration, water retention, and drainage; a stable pH between 6 and 7; and a minimum supply of nutrients. The best choice is a premium fast-draining soil with god texture that will not break down quickly.
Use a potting soil only once. Depleted used soil has poor water and air retention causing compaction and reduced drainage. Some growers mix their old potting soil with new potting soil to stretch their mix. Cutting corners this way most often costs more in production losses than is saved in soil.
Soilless mixes are popular, inexpensive, light-weight, inert, and sterile growing mediums. Premixed commercial soilless mixes are an excellent value. They retain moisture and air while allowing god drainage, strong root penetration, and even growth. Fertilizer concentration, moisture level, and pH are very easy to control. Unless fortified with nutrient, soilles mixes contain no nutrients and are pH balanced near 6.0 to 7.0.
Indoors soil mixes can be messy and a lot of work. It is much easier t buy good potting soil and mix in about 10-15 percent perlite and some form of micronutrient and trichoderma bacteria that causes roots to absorb nutrients better. Do not use backyard soil. Do not reuse soil unless it is totally clean. Avert problems with soil mixes by purchasing all the components.