Chapter 3: Vegetative Growth

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

by Jorge Cervantes

The seedling growth stage lasts for about two to three weeks after seeds have germinated. Once a strong root system is established and foliage growth increases rapidly, seedlings enter the vegetative growth stage. When chlorophyll production is full speed ahead, a vegetative plant will produce as much green , leafy foliage as it is genetically possible to manufacture as long as light, CO2, nutrients, and water are not limited. Properly maintained, marijuana will grow from one half to two inches per day. A plant stunted now could take weeks to resume normal growth. A strong, unrestricted root system is essential to supply much needed water and nutrients. Unrestricted vegetative growth is key to a healthy harvest. A plant’s nutrient and water intake changes during vegetative growth. Transpiration is carried on at a more rapid rate, requiring more water. High levels of nitrogen are needed; potassium, phosphorus, calcium, magnesium, sulfur, and trace elements are used at much faster rates. The larger a plant gets and the bigger the root system, the faster the soil will dry out. The key to strong vegetative growth and a heavy harvest is supplying roots and plants with the perfect environment.

Vegetative growth is maintained with 16 or more hours of light. I used to believe a point of diminishing returns was reached after 18 hours of light, but further research shows that vegetative plants grow faster under 24 hours of light. Marijuana will continue vegetative growth a year or longer (theoretically forever), as long as an 18-our photoperiod is maintained.

Cannabis is photoperiodic-reactive; flowering can be controlled with the light and dark cycle. This allows indoor horticulturists to control vegetative and flowering growth. Once a plant’s sex is determined, it can become a mother, clone, or breeding male, and can be harvested or even rejuvenated.

Plants show early male or female “pre-flowers” about the fourth week of vegetative growth. Cloning, transplanting, pruning, and bending are all initiated when plants are in the vegetative growth stage.

Clones and Cloning

Marijuana can be reproduced (propagated) sexually or asexually. Seeds are a product of sexual propagation; cuttings or clones are the result of asexual or vegetative propagation. In its simplest form, taking a cutting or clone involves cutting a growing branch tip and rooting it. Technically, cloning is taking one cell of a plant and promoting its growth into a plant. Marijuana growers often refer to a clone as meaning a branch of a cannabis pant that has been cut off and rooted.

Cloning reduces the time it takes for a crop to mature. Productive growers have two rooms, a vegetative / cloning room, about a quarter size of a second room used for flowering. Smaller vegetative plants take up less space than older flowering plants. For example, a 250- or 400-watt metal halide could easily illuminate vegetative plants and clones that would fill a flowering room lit by three 600-watt HP sodiums. If the halide is turned off, fluorescent and compact fluorescent amps are more economical and work well to root clones.

Combine eight-week flowering / harvest cycles with continuous cloning to form a perpetual harvest. One easy-to-implement scenario is to take two clones every four days, and harvest one ripe female every other day. Every time a plant is harvested, one or two rooted clones are moved from a constantly supplied vegetative room into the flowering room. This regimen gives a grower 30 flowering clones that are on a 91 day schedule. It takes 91 days from the time a clone is cut from the mother plant until the day its harvested. Using this schedule, a grower would have 30 clones, 10 vegetative plants, and 30 flowering plants growing at all times.

induce clones to flower when they are four to twelve inches tall to make most efficient use of HID light. Artificial light diminishes to the square of the distance, which means that foliage four feet away from the bulb receives one fourteenth as much light as if it were one foot away! Foliage that is shaded or receives less light grows slowly and looks spindly.

Short crops of cones in small containers are much easier to move and maintain than big plants in big containers. Short clones are also easy and efficient to grow in greenhouses and outdoors.

Well-illuminated, strong clones grow fast and have less chance of being affected by pests and diseases. Fast growing clones develop more quickly than spider mites can reproduce. By the time a spider mite infestation is noticed and sprayed, the plants are a few weeks from harvest. Clones are also easy to submerge in a miticide when small

Experiments with clones are consistent and easy to control. Genetically identical clones respond the same to different stimuli, such as fertilizer, light, bending, etc. After experimenting on several crops of clones from the same mother, a grower has a very good idea what it takes to make them grow well.

Mother Plants

Any plant can be cloned, regardless of age or growth stage. Take clones from mother plants that are at least two months old. Plants cloned before they are two months old may develop unevenly and grow slowly. Clones taken from flowering plants root quickly but require a month or longer to revert back to vegetative growth. Such rejuvenated clones occasionally flower prematurely, and buds are more prone to pest and disease attacks.

Any female can become a mother. She can be grown from seed or be a clone of a clone. I interviewed several growers who made clones of clones more than 20 times! That is, clones (C-1) were taken from original female grown from seed. These clones were grown in the vegetative stage, and clones (C-2) were taken from the first clones (C-1). Blooming was induced in (C-1) two weeks later and (C02), grown in the vegetative stage. Then, clones (C-3) were taken from the second clones (C-2). This same growing technique is still going on with clones of clones well past (C-20) and there has been no apparent breakdown in the potency of the vigor of the clone. However, if mothers suffer stress, they produce weak clones. Mothers that are forced to flower and revert back to vegetative growth not only yield less, they are stressed and confused. Clones that grow poorly are generally the result of poor, unsanitary coning practices.

A clone is an exact replica of the mother pant. Each mother’s cell carries a DNA blueprint of itself. Radiation, chemicals, and poor cultural practices can damage this DNA. Unless damaged, the DNA remains intact.

A female plant will reproduce 100 percent females, all exactly like the mother. When grown in the exact same environment, clones from the same mother look alike. but the same clones subjected to distinct environments in different grow rooms will often look different.

A six month old plant produces more cannabinoids than a one month old plant. By cloning, a horticulturist is planning a THC-potent plant that will continue to grow in potency at a very rapid rate. A month-old rooted clone acts exactly like a four-month old plant and can be induced easily to flower with a 12-hour period.

Keep several mother plants in the vegetative stage for a consistent source of cloning stock. Start new mother from seed every year. Give mother plants 18-24 hours of light per day to maintain fast growth. For best results, give mothers abut ten percent less nitrogen, because less nitrogen promotes rooting in clones.

Negative Points

Clones grow slower than F1 hybrid plants grown from seed. An F1 hybrid is the heterozygous first filial generation – pollen and ovule. F1 hybrids have “hybrid vigor” which means that this cross will grow about 25 percent bigger and stronger than cuttings. hybrid vigor also makes plants less susceptible to pest and disease problems

Always start with the best mothers you can find. A mother plant yields clones in her image. If the mother plant lacks potency, harvest weight, or is not pest and disease resistant, the clone shares her drawbacks. These weaknesses are compounded when growing only one strain. An unchecked pest or disease infestation could wipe out the entire crop.

Some growers have a difficult time learning to make clones. If this is the case, continue to work through the little problems one step at a time, and you will learn. Some people have a little longer learning curve when cloning is involved. Take five t ten practice clones before making a serious cloning. You can also work with strains that are easy to clone.

Plants that are easy to clone

Most Skunk and Indica strains are easy to clone. Growers and sick plants cause most clone rooting problems. Weak plants that lack vigor provide slow-rooting weak clones. Poor growing conditions also affect clone strength.

Harder to clone:

Ruderalis Indica and Ruderalis Skunk do not make suitable mother plants due to their auto-flowering capability. Outdoor strains with a slight tendency to pre-sex in an 18hr photoperiod include: Early Girl, Early Skunk and many others.

Getting Ready

Cloning is the most traumatic incident cannabis plants can experience. Clones go thru an incredible transformation when they change from severed growing tip to a rooted plant. Their entire chemistry changes. the stem that once grew leaves must now grow roots in order to survive. Clones are at their most tender point in life now.

Clones quickly develop a dense system of roots when stems have a high carbohydrate and low nitrogen concentration. Build carbohydrate levels by leaching the growing medium with copious quantities of water t flush out nutrients. The growing medium must drain very well to withstand heavy leaching without becoming waterlogged. Reverse foliar feeding will leach nutrients from leaves, especially nitrogen. To reverse foliar feed, fill a sprayer with clean water and mist mother heavily every morning for three or four days. Older leaves may turn light green; growth slows as nitrogen is used and carbohydrates build. Carbohydrate and hormonal content is highest in lower, older, more mature branches. A rigid branch that folds over quickly when bent is a good sign f high carbohydrate content

Hormone content is different in different parts of the plant. Root growth hormones are concentrated near the base of the plant close to the main stem. This is the oldest portion of the plant and is where most root hormones are located. The top of the plant contains older hormones; cuttings taken from this part root slowly.

Small clones with few leaves root faster than big cuttings with many leaves. At first leaves contain moisture but after a few days, the stem is no longer able to supply enough moisture to the leaves, and the clone suffers stress. A small amount of leaf space is all that is necessary for photosynthesis to supply enough energy for root growth.


An embolism is a bubble of air that gets trapped in the hole in the stem. Embolisms occur when you take big clones and lay them n the counter before placing in water or a growing medium. When an embolism happens, fluid flow stops, and clones die. After taking cuttings, immediately dip them in water or a growing medium to prevent air from getting trapped in the hollow stems. Eliminate the threat of an embolism by taking cutting under water.

Clones root well within a pH range of five to six. Aeroponic clone gardens normally do best with a pH of five to five and a half. Most diseases grow poorly below these pH levels. Always make sure there is plenty of air in the rooting medium; this will stimulate root growth.

Do not kill clones with kindness and fertilizer. At best, giving clones an excess dose of fertilizer causes rooting to be delayed. In fact, a good dose of ammonium nitrate, a common fertilizer, will stop root hair from growing.

If an infestation occurs, apply aerosol pyrenthrum. Remember, all pesticides, natural or not, are phytotoxic. Spraying cuttings is a bad idea in general. If you must use sprays, use natural organic sprays, apply them when it is cool, and keep their use to a minimum.

Use anti-desiccant sprays sparingly, if at all, and only if a humidity dome is unavailable. Anti desiccant sprays clog stomata and can impair root growth in clones.

Do not over-water clones. Keep the medium evenly moist, and do not let it get soggy.

Any kind of stress disrupts hormones and slows rapid growth.

Keep the cloning area clean. Do not take clones where fungus spores and diseases are hiding! Pythium is the worst! Pythium flourishes in high temperatures and excessive moisture. Mites, whiteflies, thrips, etc., love weak tender clones. Remove infested clones from the room. Cooler conditions, 65-78F, slow mite and fungal spore reproduction and allow you to avert an infestation.

Rooting Hormones

Root-inducing hormones speed plant processes. When the stem of a cutting develops roots, it must transform from producing green stem cells to manifacturing undifferentiated cells and, finally, to fabricating root cells. Rooting hormones hasten growth of undifferentiated cells. Once undifferentiated, cells quickly transform into root cells. Three substances that stimulate undifferentiated growth include napthalenaecetic acid (NAA), indolebutyric acid (IBA) and 2, 4-dichlorophenoxyacetic acid (2, 3 DPA). Commercial rooting hormones contain one, two, or all of the above synthetic ingredients and often include a fungicide to help prevent damping-off.

Rooting hormones are available in liquid, or powder form. liquid and gel types penetrate stems evenly and are the most versatile and consistent. Powdered rooting hormones adhere inconsistently to stems, penetrate poorly, spur uneven root growth, and yield a lower survival rate.

Liquid rooting hormones can be mixed in different concentrations. Always mix the most dilute concentration for softwood cuttings. Apply any rooting hormone containing IBA only once. If exceeded in concentration or duration, IBA applications impair root formation. As soon as cuttings are taken, clones start dispatching rooting hormones to the wound. They arrive in full force in about a week. The artificial rooting hormone fills the need until natural hormones take over.

Give cuttings a 5-15 second dip in concentrated solutions of IBA and NAA, 500-20,000 ppm. With a quick dip, stems evenly absorb the concentrated hormone.

Relatively new to the market, gels have caught on everywhere. They are easy to use and practical, but are not water soluble. Once applied, gels hold and stay with the stem longer than liquids or powders.

Rooting powders are a mixture of talc and IBA and / or NAA and are less expensive than liquids or gels. To use, roll the moistened end of your cutting in the powder. Apply a thick, even coat. To avoid contamination, pour a small amount into a separate container, and throw away any excess. Tap or scrape excess powder off the cutting; excess hormones can hinder root growth. Make a hole bigger than the stem in the rooting medium. If the hole is too small, the rooting powder get scraped off upon insertion.

You can also spray clones with a single foliar spray of dilute IBA (50-90 ppm). Be careful to spray just enough to cover leaves. Spray should not drip off leaves. An IBA overdose slows growth, makes leaves dwarf, and could even kill the clone.

Some growers soak their cuttings in a dilute solution (20-200 ppm IBA and/or NNA) for 24 hours. But I have seen few growers use this time-consuming technique.

To determine the rooting hormone concentration in parts per million, multiply the percentage listed by the manufacturer by 10,000. For example, a product with 0.9% IBA contain 9000 ppm IBA.

An all-natural, root-inducing substance is willow (tree) water. The substance in all willow trees that promotes rooting is unknown, but repeated experiments have proven willow water promotes about 20 percent more roots than plain water. This willow water is mixed with commercial rooting hormones for phenomenal results.

To make willow water rooting compound, find any willow tree and remove some of this year’s branches that are about one and a half inches in diameter. Remove the leaves, and cut the branches into one-inch lengths. Place one-inch willow sticks on end, so a lot of them fit in a water glass or quart jar. Fill the jar with water, and let it soak for 24 hours. After soaking, pour off the willow water, and use for rooting hormones. Soak the marijuana cones in the willow water for 24 hours, the plant in rooting medium,. If using a commercial liquid rooting hormone, substitute the willow water in place of regular water in the mix.

Before Making Clones

Making clones or cuttings is the most efficient and productive means of cannabis propagation for small growers, both indoors and out. Once females have been distinguished, you are ready t practice the simple, productive art and science of cloning.

Disinfect all tools and working surfaces to kill bacteria, fungi, viruses, and other diseases already present. Use sharp scissors, razor, or razor blade dipped in alcohol, vinegar, or bleach (five to ten percent solution). Wash your hands thoroughly beforehand.

Make sure to have all cloning supplies within arm’s reach – rooting cubes, hormone, razor or scissors, humidity dome, etc. – before you start to take clones.

Cloning: Step by Step

Step One – Choose a mother plant that is at least two months old. Some varieties give great clones even when pumped up with hydroponics and fertilizer. If a variety is difficult to clone, each the soil with two gallons of water for each gallon of soil every morning for a week before taking clones. Drainage must be good. Or mist leaves heavily with plain water every morning. Both practices hep wash out nitrogen. Do not add fertilizer.

Step Two – With a sharp blade, make a 45-degree cut across firm, healthy 0.125-0.25 inch wide branches, two to four inches in length. Take care not to smash the end of the stem when making the cut. Trim off two or three sets of leaves and growth nodes so the stem can fit into the soil. There should be at least two sets of leaves above the soil line and one or two sets of trimmed nodes below ground. When cutting, make the slice halfway between the sets of nodes. Immediately place the cut end in water. Store cut cones in water while making more clones.

Step Three – Rockwool and Oasis root cubes are convenient and easy t maintain and transplant. Fill small containers or nursery flats with coarse, washed sand, fine vermiculite, soilless mix, or, if nothing else is available, fine potting soil. Saturate the substrate with water. Use an unsharpened pencil, shop stick, nail, etc., to make a hole in the rooting medium – a one half inch from the bottom of the container to allow for root growth. Place a tray containing rooting cubes r plugs into a standard nursery rooting fat. If none exist, make holes through three-fourths of the cube for clone stems. Fill rockwool tray with water, pH 5-6. Always use strong plastic trays.

Step Four – Use a rooting hormone, and mix just before using. For liquids, use the dilution ration for softwood cuttings. Swirl each cutting in the hormone solution for 5-15 seconds. Place the cuttings in the hole in the rooting medium. Pack rooting medium gently around the stem. Gel and powder root hormones require no mixing. Dip stems in gels as per instructions or roll the stem in the powder. When planting, take special care to keep a solid layer of hormone gel or powder around the stem when gently packing soil into place.

Step Five – Lightly water until the surface is evenly moist. Keep cuttings moist at all times. Clones have no roots to bring water to eaves. Water arrives from leaves and the cut stem until roots can supply it. Water as needed to keep growing medium evenly moist. Do not let it get soggy.

Step Six – Clones root faster with 18-24 hours of fluorescent light. If clones must be placed under an HID, set them on the perimeter of the garden so they receive less intense light; or shade them with a cloth or screen. A fluorescent tube six inches above clones or a 400-watt metal halide 4-6 feet away supplies the perfect amount of light for clones to root. Cool white fluorescents are excellent for rooting.

Step Seven – Clones root faster when the humidity levels are 95-100 percent the first two days and gradually reduced to 80-85 percent during the following week. A humidity tent will hep keep humidity high. Construct the tent out of plastic bags, rigid plastic, or glass. Remember to leave openings for air to flow in and out so little clones can breathe. If practical, mist clones several times a day as an alternative to the humidity tent. Remove any slick, rotting, or dead foliage. Cut leaves in half to lower transpiration surface and to keep them from overlapping. Moisture that could foster fungus is often trapped between overlapping leaves. Keep the grow medium evenly moist so there is enough moisture to prevent cut leaves from bleeding out plant sugars that attract diseases.

Step Eight – Clones root faster when the growing medium is a few degrees warmer than the ambient air temperature. A warmer substrate increases underground chemical activity, and lower air temperature slows transpiration. For best results, keep the rooting medium at 75-80F. Growing medium temperatures above 85F will cause damage. Keep the air temperature 5-10F cooler than the substrate. A warmer growing medium coupled with cooler ambient temperature slows diseases and conserves moisture. Misting clones with water also cools foliage and slows transpiration to help traumatized clones retain moisture unavailable from nonexistent roots. Put clones in a warm place to adjust air temperature and use a heat pad, heating cables, or an incandescent light bulb below rooting cuttings.

Step Nine – Some cuttings may wilt but regain rigidity in a few days. Clones should look close to normal by the end of the week. Cuttings that are still wilted after seven days may root so slowly that they never catch up with others. Cull them out, or put them back int the cloning chamber to grow more roots.

Step Ten – In one to three weeks, cuttings would be rooted. Signals they have rooted include yellow leaf tips, roots growing out drain holes, and vertical growth of the clones. To check for root growth in flats or pots, carefully remove the root ball and clone to see if it has good root development. For best results, do not transplant clones until a dense root system is growing out the side and bottom of rooting cubes.

Cuttings are always strong and healthy-looking after you take them. After five of six days, leaves may start to change color. Leaves stay small and often turn a deeper shade of green. After about a week, lower leaves may start to yellow if their nutrient levels dissipate.

A week after being taken, clones’ stems will develop stubby callused roots called primordial. The primordial are semi-transparent to white and should look healthy. Clones produce very little green growth during this process. Once the rot and vascular transport system is in place and working properly, clones are able to experience explosive growth with proper care.

Rooting clones can handle increasingly more light as roots grow. Move the fluorescent lamps to two to four inches above plants when roots form. Fertilize with a mild fertilizer solution when all clones have started vegetative growth.

Any sign of slime, pests, or disease means there are problems, and clones should be removed from the garden. Transplant only the strongest, well-rooted clones. Slow-rooting clones should be kept in the cloning chamber or culled out. Do not move clones below bright light until they have fully developed rot systems. Once transplanted, clones are ready to harden-off.

Cloning the apex of the tip

Set up a vegetative pre-flowering area that is lit with an HID or bright compact fluorescent lamps for the rooted clones. Place them in this area to let them grow the first week or two vegetation. This area needs t be just big enough to accommodate plants from the time they are a few inches tall until they are about a foot tall and ready to be moved into the flowering room.

Air Layering

There is a good sequence of air layering in Marijuana Botany, by Robert C. Clarke. To date, I have never seen anybody use this technique. it is interesting, but normally not necessary. Cannabis is easy to root or clone.

Cloning for Sex

Determine plant sex accurately, 100 percent of the time, by “cloning for sex”. To clone for sex, take two cuttings (in case one dies) from each plant in question. Use waterproof labels and an indelible marker to identify sets of clones and corresponding parents.

Give rooting clones a 12-hour light/dark regimen. After a 12 hour day, set clones in a dark closet, or place a box over them. The dark period must be total and uninterrupted to induce flowering. Clones usually show sex within two weeks. Cull out all males except those used for breeding. Flower little females, and keep their mothers growing under 18-24 hours of light.

Growers with only one room root clones in a nursery flat, and cover it with a light-tight cardboard box for 12 hours every night. Remove the cardboard box after the lights go out to increase air circulation and ventilation.

Clones from a Flowering Female

You can clone a favorite flowering plant, but it is difficult. Clones take longer to root, and results are not always the best. Powerful flowering hormones must be reversed, and rooting hormone signals must be spent. Now is the time to give plants 24 hours of light to signal them to grow.

Cut clones from the lower green branch tips. Cut a one to two inch long stem. Trim off flowers and lower leaves. Keep two or three green leaves. If leaves have yellowed, survival chances diminish exponentially.

The earlier in the flowering stage cuttings are taken, the more rapid the rotting and the re-vegetation rate. Once a pant reaches the senescence point, leaving not enough t initiate rots.

Storing Clones

To store cuttings for later use, wrap recently cut and trimmed stems in a damp cloth or paper towel. Put the wrapped clones into a plastic bag, and store in the refrigerator. Keep the temperature above 40F. Temperatures below this level may cause plant cells to rupture. Cuttings should last in the refrigerator for about three weeks.

Clonex Root Matrix, a Growth Technology product, is a gel that allows cut clones to root and be held until they are needed.


When plants are too big for their containers, they must be transplanted to continue rapid growth. Inhibited, cramped root systems grow sickly, stunted plants. Signs of root bound plants include slow, sickly growth and branches that develop with more distance between limbs. Severely root bound plants tend to grow straight up with few branches that stretch beyond the sides of the pot. To check for root bound symptoms, remove the plant from its pot to see if rots are deeply matted on the bottom or surrounding the sides of the pot.

When growing short plants that reach full maturity in 90 days, there is little need for containers larger than three gallons (11L). Large mother plants will need a large pot if they are kept for more than a few months.

Transplant int the same type or similar growing medium; otherwise, a water pressure differential could develop between the different mediums, which sows water movement and causes slow root growth. Starting seeds and clones in root cubes or peat pots makes them easy to transplant. Set the cube or peat pot in the hole in the growing medium, and make sure growing medium is in firm contact. Remember to keep root cubes and substrates evenly moist after transplanting.

Transplanting is the second most traumatic experience after cloning. It requires special attention and manual dexterity. Tiny root hairs are very delicate and may easily be destroyed by light, air, or clumsy hands. Roots grow in darkness, in a rigid, secure environment. When roots are taken out of contact with the soil for long, they dry up and die.

Transplanting should involve as little disturbance to the root system as possible. Water helps the soil pack around roots and keeps them from drying out. Roots need to be in constant contact with moist soil in order to supply water and food to the plant.

After transplanting, photosynthesis and chlorophyll production are slowed, as are water and nutrient absorption via roots. Transplant late in the day s transplanted plants have all night to recover. Transplants need subdued light, s foliage can grow at the rate roots can supply water and nutrients. Give new transplants filtered, less intense light for a couple f days. If there is a fluorescent lamp handy, move transplants under it for a couple of days before moving them back under the HID or outdoors to harden off.

Ideally, plants should be as healthy as possible before being traumatized by transplanting. But, transplanting a sick, root bound plant to a bigger container has cured more than one ailing plant. Once transplanted, cannabis requires low levels of nitrogen and potassium and increased quantities of phosphorus. Any product containing Trichoderma bacteria or Vitamin B1 will hep ease transplant shock. Pants need a few days to settle in and re-establish a solid flow of fluids from the rots throughout the plant. When transplanted carefully and disturbed little, there will be signs of transplant shock or wilt.

Double potting is a simple transplanting technique that disturbs roots very little. To double pot a plant, cut the bottom out of the root bound pot, and set on top f another, bigger pot of soil. Roots grow down into the second pot.

Transplanting Step by Step

Step One – Water clone with half strength Trichoderma bacteria or Vitamin B1, two days before transplanting.

Step Two – Fill the three gallon container with rich potting soil or soilless mix to within two inches of the top.

Step Three – Water growing medium with a mild, quarter strength hydroponic fertilizer solution until saturated and solution drains freely out the bottom.

Step Four – Carefully remove the root ball from the container. Pace your hand over top of container with the stem between your fingers; turn it upside down, and let root ball slip out of pot into your hand. Take special care at this point t keep the rot ball in one integral piece.

Step Five – Carefully place the root ball in the prepared hole in the three gallon container. Make sure all roots are growing down.

Step Six – Backfill around the root ball. Gently, but firmly, place soil into contact with the root ball.

Step Seven – Water with half strength fertilizer containing Trichoderma bacteria or Vitamin B1. Soil should be saturated – not waterlogged – and drain freely. If rooting cube and new substrate are not identical, pay special attention to moisture levels. Let rockwool dry out enough s that rots penetrate new growing medium in search of moisture.

Step Eight – Place new transplants on the perimeter of the HID garden or under a screen to subdue sunlight for a couple of days. Once transplants look strong, move them under full light.

Step Nine

Fertilize soilless mixes after transplanting with a complete hydroponic fertilizer that contains soluble chelated nutrients. New potting soil usually supplies enough nutrients for a couple of weeks before supplemental fertilization is necessary.

Seedlings and clones can also be transplanted directly into three to five gallon pot, a system which requires fewer containers and involves less work and less possible plant stress. The larger volume of soil holds water and nutrients longer and requires less frequent watering. When clones and seedlings are transplanted directly into a five gallon container, the roots grow down, out, and around the container walls and bottom. In fact, the majority of roots grow out of soil and form a layer behind the container wall.

To encourage roots to develop a dense compact system, transplant just before they have outgrown their container. Transplanting a well-rooted clone in a root cube into a four inch pot and transplanting the four inch pot into a three gallon pot or grow bag causes rots to develop a more extensive system in a small ball of growing medium. Successful transplanting causes minimal stress. Most marijuana crops are in the ground for such a short time that bungled transplanting costs valuable recuperation time and loss in production.

transplant clones and seedlings into raised beds and large planter boxes directly from four inch pots. As many as 20 plants can be transplanted into a 24 x 24 x 12 inch planter, but six to twelve plants will yield about the same dry weight of buds. Once plants start crowding and shading one another, bend stems outward and tie them to a trellis attached to the planter. large planters require less maintenance. The larger mass of soil retains water and nutrients much longer and more evenly. One downside is that all plants must receive the same water and diet.

Three gallon containers are the idea size for two to three foot tall plants. Larger pots are usually unnecessary because plants grow no longer than a week or two in the vegetative stage and six to ten weeks flowering. Smaller three gallon pots are easy to move and handle. Roots also grow less during flowering. By the time a plant is pot bound, it is ready to harvest. I used to recommend up to a five gallon container for plants that are harvested after 90 total days of life. I now believe this is a waste. While the smaller containers require daily watering, they produce harvests comparable to those of five gallon containers.

Mother plants are much larger, grow longer, and can require containers up to 30 gallons in size. However, mother plants grow quite well in five or ten gallon hydroponic containers for a year or longer. If you plan to keep a mother plant for more than a few months, grow it hydroponically in its own container for best results.

Pruning and Bending

Pruning and bending a plant redirects growth hormones. Pruning affects the plant more drastically than bending. Selective pruning and bending allow us to manipulate auxin hormone levels in branch or branch tip causes hormonal balances to shift. Cutting the meristem (top growth tip) of a cannabis plant will diffuse auxins and cause greater concentrations in lower branch tips. Bending a growing tip changes hormone concentrations less than pruning.


Always use clean instruments when pruning. A straight razor, single edge razor blade, a sharp pair of pruners, or a pair f scissors all work well. Sanitize clippers and blades between between cuts by dipping in rubbing alcohol. Use indoor pruners only in the indoor garden. Pruners used outdoors have everything from spider mites t fungus spores on them. If outdoor clippers must be used, dip in rubbing alcohol to sterilize before making cuts.

After pruning, the open wound invites diseases and pests. Wash your hands and tools before and after pruning. Make cuts at a 45 degree angle to discourage moisture from sitting on wounds.

Avoid pruning up to a month before inducing flowering. Since pruning diffuses floral hormones, flowering is retarded. If heavily pruned shortly before flowering, peak maturation is delayed for a week or longer. It takes a month or longer for hormones to build up to pre-pruning concentrations.

Leave leaves alone! Removal of healthy leaves hacks up a healthy pant. Removing large fan or shade leaves does not make plants more productive even though this practice supplies more light to small leaves and growing tips. Plants need all their eaves to produce the maximum amount of chlorophyll and food. Removing leaves slows chlorophyll production, stresses the plant, and stunts its growth. Stress is a growth inhibitor. Remove only dead leaves that are more than 50 percent damaged.

Remove spindly branches and growth that is not collecting light energy, including dead and dying leaves. Pruning lower branches concentrates auxins in upper branches which forces growth upwards. Cut lower branches off cleanly at the stem s no stub is left t rot and attract pests and diseases. If you must harvest a little smoke prematurely, removing a few lower branches will diminish the harvest the least.

Pruning out spindly branches and growth inside plants pens up the interior and provides more and better circulation. It also allows light to reach deeper inside plants.

Not pruning has several advantages. Floral hormones are allowed to concentrate in tips of branches causing buds t grow stronger and denser. Unpruned plants have less space to bush out laterally and tend to grow more upright. Clones are sent into flowering room after 1-30 days in the vegetative room. All little clones are packed tightly together in three gallon pots. Each one of the plants is taking up the minimum amount of marijuana. Light is much more intense, and the entire plant grows flower tops with few fan leaves.

Most successful growers do not prune at all, especially if growing a short clone crop that is only two to three feet tall. Short clone tops require no pruning to increase light to bottom leaves or to alter their profile. “No pruning” is the easiest and most productive method when growing short crops.

Pinching back or pruning tops (branch tips) causes the two growing shoots just below the cut to grow stronger and bigger. This increases the number of top or main buds. Pruning tops also diffuses floral hormones. These hormones (auxins) prevent the lateral buds from growing very fast. All lower branches develop more rapidly when the terminal bud is removed. The further a branch is from hormones at the plant tip, the less effect the auxins have.

To pinch back a branch tip, simply snip it off below the last set or two of leaves. Pinching off tender growth with your fingers helps seal the wound and is often less damaging to plants than cutting. When the main stem is pinched back, side and lower growth is stimulated. When all the tops are pinched back, lower growth is encouraged. Continually pinching back, as when taking clones from a mother, causes many more little branches t form below the pruned tips. Eventually, the plant is transformed into a hedge-like shape. Most growers do not pinch plants back, because it diminishes the yield of prime, dense tops; but it may not affect the overall weight of dried smoke.

Supercropping is a form of pinching back or pruning branch tips. We are not sure who or when the term r buzzword was coined. We do know that there are several different versions of supercropping “invented” by innovative growers.

Supercropping can also incorporate FIM pruning which is explained below. It can be combined with bending, too. Some people go to the point of mutilating plants by breaking branches a few inches below main buds. Removing healthy leaves so that “budding sites get more light” is also practiced by some supercroppers.

Pruning all the branches or removing more than 20 percent of the foliage in a short time frame stresses plants too much and diminishes harvest. But if taking clones, some growers effectively prune a mother down to stubby branches and let her recuperate for a month or longer.

Pruning to much over time may alter hormonal concentrations, causing spindly growth. This is often the case with mother plants that provide too many clones. The mother must rest and and gain girth, because small, spindly branches root poorly.

Remove all but the four main branches. The meristem (central stem) is removed just above the four lowest (main) branches. Removing the central leader concentrates the floral hormones in the four remaining branches. Fewer branches are stronger and bear a larger quantity of dense, heavy flower tops. Remove the stem above the fur main branches; do not remove leaves on the main branches. Select plants with three sets of branch nodes about six weeks old, and pinch or prune out the last set of nodes so that two sets of branches remain. Move plants into the flowering room when they are about 12 inches tall. Skunk #1 and similarly robust bloomers should be set in the flowering room when about six to eight inches tall.

The FIM Technique was coined by an anonymous High Times reader from South Carolina in the July 2000 issue of the magazine. The technique became legendary, ever since the grower wrote: “this pruning technique could revolutionize indoor gardening.” The South Carolina grower tried to pinch the tip of a plant and said “Fuck, I Missed!” when he did not remove the entire bud and coined the acronym FIM.


Bending is similar to pruning, in that it alters the flow of hormones. bending efficiently neutralizes the effect of the growth inhibiting hormone. Bending is much easier on plants than pruning. To bend, lean a branch in the desired direction and tie it in place. Branches can take a lot of bending before they fold over or break. Even if a branch folds, tie it in place; if necessary, use a wooden splint. The stem will heal itself. young, supple branches take bending much better than old, stiff ones. Bending branches horizontally will encourage the buds to grow vertically towards the light. Each bud will turn into an impressive top, because they all receive more light. A wooden planter box with a lattice trellis alongside makes a great anchor to tie bent plants to.

Wire ties, the kind used to close bread sacks, can be purchased at a nursery. Wire ties are either pre-cut or cut to length by the grower. Plastic coated electronic and telephone cable wire wire will also work well. They are fastened with a simple twist and stay rigid leaving the stem breathing room. But if applied too tightly around a stem, the liquids cannot flow, and death could result.Be gentle when bending, even though cannabis can take much abuse. Sometimes a crotch will separate or a branch will fold over, cutting off fluid flow. These mishaps are easily fixed with a small wooden splint snugly secured with wire ties or duct tape to support the split and broken stem.

Growers also combine bending and pruning. It is easy to prune too much, but it is hard to over bend.

Air Pruning Roots

When roots grow to the end of the container and are exposed to air, they stop growing. The air naturally prunes roots. They cannot grow out the end of the pot, because the climate with little moisture and lots of air is too inhospitable.

Root Pruning

Root pruning could be necessary to give new life to potbound plants outdoors r in greenhouses. Removing roots will not make plants grow faster; in fact, it will slow growth for about two weeks. Once new roots start to grow, growth rebounds. About mid-summer, rot-prune plants that must stay in the same size container. Root pruning will keep plants manageable and much easier to maintain.

Chemical Root Pruning

Chemical root pruning is an excellent way to control root growth inside containers. Commercial nursery people have been using chemical root pruning for many years with outstanding results.

Uncle Ben used a product called Griffin’s Spin-Out that consists f copper hydroxide suspended in a carrier. To use, simply spray paint the inside of the containers with two cats f Griffin’s Spin-Out. Root s grow to within a fraction of an inch of the copper hydroxide, then stop. Roots will not touch the unpleasant compound. The result is similar to what happens above ground when when new, lower growth is stimulated as branch tips are pruned. When pruned with copper hydroxide paint, more roots develop overall, and they grow in the entire root ball, especially in the center. Plants with a dense root system dispersed evenly throughout the rot ball are easier t maintain, and they grow bigger in smaller containers.


Little is known about grafting cannabis. Yes, it is possible to graft cannabis to hops. Most often the hop stem is grafted to a cannabis rootstock. The plant will live; however, it will not produce THC.

I asked a number of growers if they had experimented with grafting, and none had. Grafting an indica stem to a large sativa rootstock would be an interesting experiment. The larger root system could easily supply water and nutrients to the smaller indica plant. The resulting plant would be drought resistant.


Cannabis grows best and produces heaviest when it is given a stable environment. Stressed plants produce less than unstressed plants. Stress-induced trauma include withholding water, photoperiod fluctuation, low light intensity, ultraviolet light, nutrient toxicities and deficiencies, cold and hot soil, ambient temperatures and mutation. In addition, any overt application of growth hormones such as B9 hormone, gibberellins, cytokinins, abscisic acid, ethylene, colchicine, etc., cause stress.

Stress can pause to produce more resin, but it simultaneusy causes odd and / or reduced o. For example, Felix, a Swiss outdoor grower, grew a filed of cannabis at 900 feet and another at 4200 feet. The upper field suffered stress, because it is exposed to cooler temperatures and more ultraviolet radiation. Plants there produce 25 percent more resin-packed THC than plants in the lower field. But, plants that grow at 900 feet yield at least 25 percent or more dry weight than plants at the 4200 foot elevation.

Removing large green shade leaves allows more light to shine on smaller leaves, but it also causes growth to slow and harvest to diminish. Remove only leaves that are more than half damaged by pests or diseases. often, partially yellow leaves green up once stress is eliminated. Removing spindly, dimly lit lower branches stresses plants much less than removing leaves to speed growth of upper foliage.

Mutilating plants by breaking the trunk, driving a stake through the trunk, torturing r slapping them around might increase resin production, but most often the stress retards growth and causes other problems. Withholding water may also cause more resin production, but it impairs growth and diminishes leaf, stem, and flower production. Water stress slows or stops clones from rooting. If clones have too many leaves and are too busy transpiring, root growth is very slow. Conversely, waterlogged rooting mediums harbor no air, and rooting mediums slowed to a crawl.

Marijuana Horticulture

1 comment to Marijuana Horticulture Chapter 3: Vegetative Growth


    Hi im chris, id lije to know if this indica four topped plant looks good? its 6 weeks old. please email me id like to send you pictures.

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