Cannabis cultivation

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Typical home-grown organic seedless bud compared to a cigarette pack.

This article presents common techniques and facts regarding the cultivation of the flowering plant cannabis, primarily for the production and consumption of marijuana buds. Cultivation techniques for other purposes (such as hemp production) differ. A basic description of hemp cultivation can be found in the US film Hemp for Victory.

Evidence found in ancient burial sites indicate that humans have been experimenting with cannabis spiritually and medicinally since at least the 3rd millennium BC.[1] Herodotus, an early Greek historian, described how the Scythians of the Middle East used cannabis in steam baths.[2] The status of the plant has changed in recent years. In the early 20th century the US outlawed cultivation, consumption and trade of all cannabis species. Thereafter the vast majority of countries have followed a similar paradigm, imposing penalties that range from a small fine to incarceration and execution.[3][4]



A flowering cannabis plant.

Cannabis belongs to the genus Cannabis in the family Cannabaceae and includes four species, C. sativa, C. indica, C. afghanica, and C. ruderalis (APG II system).[5] It is typically a dioecious (each individual is either male or female) annual plant (life period: April–September).[6][7][8]

C. sativa and C. indica generally grow tall (some varieties reach 4 m) and their females start the production of flowers rich in THC (1% to 29%) as the season changes from summer to autumn. C. ruderalis is very short, produces only trace amounts of THC and flowers independently of the photoperiod and according to age.[9] However, commercial cross-bred hybrids containing both ruderalis, indica and/or sativa genes exist (usually called autoflowering), the "low rider" being the most famous.

Cultivation requirements

Cannabis needs certain conditions to flourish.

Growth medium

Soil is required, except for cannabis grown with hydroponics or aeroponics


The optimal day temperature range for cannabis is 24 to 30 °C (75 to 86 F). Temperatures above 31 °C and below 15.5 °C seem to decrease THC potency and slow growth. At 13 °C the plant undergoes a mild shock, though some strains withstand frost temporarily.[9][10][11] Frost occurs when air temperatures dip below 32°F (0 °C) and ice crystals form.


Light can be natural (outdoor growing) or artificial (indoor growing).

When artificial light is used, from the germination until the flowering stage, the plant typically remains under a regime of 16–20 hours of light and 4–8 hours of darkness, although the plant can use a full 24 hours of light without harm. It is worth noting that there is an ongoing debate over the importance of the "Dark Period". It has been proven that, when subjected to a regimen of constant light without a dark period, most types of flora, including Cannabis, will begin to show signs of decreased photosynthetic response, as well as lack of vigor, and an overall decrease in vascular development. There is no defined "flowering stage", unless you are discussing an auto-flowering variety (Cannabis Ruderalis). Typically, flowering is induced by changing the light schedule to 12/12, or 12 hours of light and 12 hours of darkness. Flowering in cannabis is triggered by a hormonal reaction within the plant that is set on by an increase in its dark cycle. In other words, a plant needs sufficient prolonged darkness for calyx development(flowering) to begin. Some Indica varieties can take as little as 8 hours of dark to begin flowering, whereas some Sativa varieties can take up to 13.


Watering frequency and amount is determined by many factors, including temperature and light, the age, size and stage of growth of the plant and the medium's ability to retain water. A conspicuous sign of water problems is the downward wilting of leaves.[12] Too much water can kill young cannabis plants. In order to determine whether a plant needs watering, the cultivator either sticks his or her finger into the soil to see whether the soil below the surface is dry or lifts the pot to feel the weight compared to just after watering. Usually these simple but effective techniques are far more accurate than digital soil moisture meters which are notoriously inaccurate and unreliable.[citation needed]


Fertilizer burn on a leaf

Nutrients are the food of plants and come in the form of fertilizers that can be chemical or organic, liquid or powder and may contain several elements (see also: fertilizer). Commercial fertilizers must indicate the levels of NPK (mentioned above). During the vegetative stage, cannabis needs more N than P and K, while during the flowering stage, P is more essential than N and K. The presence of secondary nutrients (calcium, magnesium, sulfur) is recommended. Also there are seven micro nutrients (Iron, boron, chlorine, manganese, copper, zinc, molybdenum) that are not extremely important and rarely manifest as deficiencies.

Fertilizers are vital for good cannabis growth but must be used frugally to avoid burning the plant. As a general rule, half the amount suggested in a bottle may be given each time.[13]

Because cannabis is acclimatized to virtually every growing region on Earth, its nutrient needs vary widely with its genetics and can truly only be determined with experience. Chemical plant foods vary greatly maker to maker, and some can be used at full strength, or the strength listed for plants with large fruits like the tomato.

Stages of development


C. indica seeds

Duration: 12 hours to 8 days. Warmth, darkness and moisture initiate metabolic processes such as the activation of hormones that triggers the expansion of the embryo within the seed. Then the coating cracks open and produces a small embryonic root that begins growing downward because of gravitropism, if placed in a proper growing medium. Soon (after 2–4 days) the root is anchored and two circular embryonic leaves (cotyledons) emerge in search of light and the remains of the seed shell are pushed away. This marks the beginning of the seedling stage.

Seeds may be germinated by soaking them between wet paper towels, in a cup of water at room temperature for 24 hours, in wet peat pellets, or directly in potting soil. Most tap water at tepid temperature is sufficient to wet the pellets - despite common belief distilled or reverse osmosis water is not needed unless mains water is of particularly poor quality. Peat pellets are often used as a germinating medium because they make it unnecessary to transplant the fragile seedlings and the saturated pellets with their seedlings can be planted directly into the intended growing medium with a minimum of trouble and effort, or shock to the plant.

A technique that achieves high germination rates is the following: First, put seeds in a cup of water. All seeds initially float on the surface, so they must be forced to immerse completely. Then leave the cup in a lukewarm dark place for no more than 24 hours. (Otherwise the seeds could drown.) Shortly most will sink to the bottom, which indicates that water penetrated the shell. Finally, place the seeds in a constantly damp, lukewarm, dark environment, such as wet cotton or a towel. Dirty hands (even traces of nicotine on them) can damage seeds. As soon as the root appears, the seeds are ready to be placed in a growing medium.

Seedling phase

A very young C. sativa seedling. The tips of the first two true leaves are emerging between the two round seed leaves (cotyledons)

Duration: 1–4 weeks. The seedling stage begins when the seed breaks and exposes its round “seed leaves” or cotyledons. This is the most fragile time during the entire life cycle of the cannabis plant. It is important to keep a constant atmosphere with a moderate humidity level and medium to high light intensity. Most indoor growers use compact fluorescents or T5 fluorescents during this stage as they give off little heat. HPS and MH lights give off large amounts of radiant heat and increase the rate of transpiration in the plant. Seedlings have small root systems and can dry out very quickly, so keeping the medium moist is important.

The plant can begin to sex itself in this stage, but if time is an issue one can induce sexing by switching to a 12/12 hour period. Once sex is determined you can remove the males and switch the cycle back to vegetation stage by inducing an 18/6 hour period. However some would advise against this method, since large scale testing has shown plants left to show pre-flowers naturally after a period of 4–6 weeks on average both yield more and give bud that is 2-3x more potent. A quicker method would be to take a clone off your seedling when old enough, root it then flower it in another area. Forcing a plant to flower(12 hours light 12 hours dark), then reveg can take weeks to get vegetative growth to resume again.

Vegetative phase

A young male cannabis plant during early flowering stage

Duration: 1–2 months indoors. In this stage the plant needs all the light (at least 18 hours) and nutrients (food) that it can use, depending on the genetics of the particular plant. It continues to grow vertically and produce new leaves. The sex is starting to reveal itself, which is a sign that the next stage begins. Concurrently the root system expands downwards in search of more water and food. Some newly developed strains (auto flowering hybrids) omit the vegetative stage and pass directly from seedling to pre-flowering.

When the plant possesses seven sets of true leaves and the 8th is barely visible in the center of the growth tip, or shoot apical meristem (SAM), the plant has entered the vegetative phase of growth. During the vegetative phase, the plant directs its energy resources primarily to the growth of leaves, stems, and roots. A strong root system is required for strong floral development. A plant needs 1 or 2 months to mature before blooming. The plant is ready when it has revealed its sex. Plant size is a good indicator of sex. Females tend to be shorter and branchier due to their raceme type inflorescence than males, whose flowers grow in panicles. The males tend to have fewer leaves near the top and females have more leaves surrounding the flowers.[14] The males are then usually culled when they are identified, so that the females will not be pollinated, thus producing "sin semilla" ("without seed") buds.

During the vegetative phase, cultivators generally employ an 18- to 24-hour photo period because the plants grow more quickly if they receive more light, although a warmer and cooler period are required for optimal health.[15] Although no dark period is required, there is debate among cultivators as to whether a dark period is beneficial, and many continue to employ a dark period.

The amount of time to grow a cannabis plant indoors in the vegetative stage depends on the size of the flower, the light used, the size of the space, and how many plants are intended to flower at once, and how big the strain gets in "the stretch" (i.e., the first two weeks of flowering).

Cannabis cultivators employ fertilizers high in N (nitrogen) and K (potassium) during the vegetative stage, as well as a complete micro nutrient fertilizer. The strength of the fertilizer is gradually increased as the plants grow and become more hardy.

The modification of a plant's growth habit is called training. Indoor cultivators employ many training techniques to encourage shorter plants and denser canopy growth. For example, unless the crop is too large to be extensively pruned, cultivators remove adventitious growth shoots, often called suckers, that are near the bottom of the plant and/or receive little light and will produce poor quality buds.

Many cultivators also employ other techniques:


Is done by removing the top of the apical meristem (dominant central stem), called the apex or terminal bud, to transfer apical dominance (the tendency for the apex to grow more rapidly than the rest of the plant) to the shoots emanating from the two nodes immediately beneath the pruning cut. This process can be repeated on one or both of the two new meristems, when they become apically dominant, with the same results. This process can actually be repeated almost infinitely, but over-diffusion of apical dominance produces smaller, lower quality buds, so it is usually done no more than a few times. Topping also causes more rapid growth of all of the branches below the cut while the plant heals.


Pinching (also called super cropping) is similar to topping in that it causes lower branches to grow more rapidly, but the apical meristem maintain apical dominance, which is especially useful if the plant has already been topped. Pinching is performed by firmly pinching the apical meristem(s) so as to substantially damage vascular and structural cells but without totally breaking the stem. This causes lower limbs to grow more rapidly while the pinched tissue heals, after which time the stem resumes apical dominance.


LST stands for Low Stress Training and is another form of supercropping, many times referred to as LST super cropping. This technique involves bending and tying the plants branches to manipulate the plant into a more preferred growth shape. This method of training works very well for indoor growers who need to illuminate their plants using overhead lights. Since light intensity greatly diminishes with increased distance (Inverse-square law) LSTing can be used to keep all growth tips (meristem) at the same distance from the light and can achieve optimal light exposure. LST can be used in conjunction with topping, since topping increases axial growth (side shoots). Topping is often done a few weeks before beginning LSTing. LSTing works by changing the distribution of hormones, more specifically Auxins, in the plant. LSTing resembles the training of grape vines into their support lattices. Outdoor gardeners also employ training techniques to keep their plants from becoming too vertical.

Pre-flowering phase

Also called the stretch, this takes one day to two weeks. Most plants last for 10–14 days after switching the light cycle to 12/12. Plant development increases dramatically, with the plant doubling or more in size. (See reproductive development below.) Production of more branches and nodes occurs in this stage, as the structure for flowering grows. The plant starts to show calyx where the branches meet the stem (nodes). Pre-flowering indicates the plant is ready to flower.

Flowering phase

The flowers of a male cannabis plant

Duration: Varies from about 6 to 22 weeks with pure indicas having a shorter flowering time than pure sativas. Mixed indica/sativa strains have an intermediate flowering time. The sex is clearly revealed in the first two weeks of 12/12. Males produce little balls clustered together like grapes. Most plants (except auto flowering strains that flower independently of photoperiod) can flower under diminished light. In nature, cannabis plants sense the forthcoming winter as the Earth revolves around the Sun and daylight reduces in duration (see also season). If females are not pollinated (fertilized by male pollen) they start to produce buds that contain sticky white resin glands or trichomes in a final attempt for pollination by windborne male pollen. The trichomes produce resins containing the largest amounts of THC and CBD, the two main psychoactive substances. Fertilized females produce resinous trichomes but more plant energy is sunk into seeds, which can be half the mass of a fertilized inflorescence; thus, to maximize resin per gram, seedless cultivation is preferred.

Buds of the first case are called sinsemilla (it is really two words: "sin semilla," which translates to "without seeds" in Spanish, but is often misspelled as one word). Potent sinsemilla is especially important to medical users, to minimize the amount of cannabis they must consume to be afforded relief. Cannabis with seeds is generally considered to be of inferior quality and/or grown with inferior technique.

Indoors, cannabis is induced into flowering by decreasing its photoperiod to at least 10 hours of darkness per day. In order to initiate a flowering response, the number of hours of darkness must exceed a critical point. Generally the more hours of darkness each day, the shorter the overall flowering period but the lower the yield. Conversely, the fewer hours of darkness each day, the longer the overall flowering period and the higher the yield Traditionally most growers change their plants lighting cycle to 12 hours on and 12 hours off since this works as a happy medium that most strains respond well to. This change in photoperiod mimics the plant's natural outdoor cycle, with up to 18 hours of light per day in the summer and down to less than 12 hours of light in fall and winter.[16] Some 'semi-autoflowering' strains that have been bred exclusively for outdoor use, particularly in outdoor climates such as that of the UK, the plants will start flowering with as much as 16-17 hours of light per day. Usually they can start flowering in July and finish far earlier than other strains, particularly those that haven't been bred as outdoor strains. Because the weather in northern latitudes gets very wet and cold during October when many strains start to finish flowering, these semi-autoflowering strains give an advantage as they are far less likely to suffer from botrytis (grey mold) which is caused by wet weather. Alternatively growers may artificially induce the flowering period during the warmer months by blacking out the plants for 12 hours a day i.e. by covering the plants with black plastic for example, which excludes all light during this period so the plant can flower even during long days.

Although the flowering hormone in most plants (including cannabis) is present during all phases of growth, it is inhibited by exposure to light. To induce flowering, the plant must be subject to at least 8 hours of darkness per day; this number is very strain-specific and most growers flower with 12 hours of darkness to be safe.

Flowers from certain plants (e.g. cannabis) are called Calyx, and are (with cannabis) the most prized part of the plant. In late flowering the calyx are easily visible to the naked eye. Calyx development begins approximately 1–2 weeks after the photoperiod is reduced. In the first weeks of flowering a plant usually doubles in size and can triple. Calyx development ends around 5 weeks into flowering and is proceeded by a period of Calyx “swelling”. During this time the buds greatly increase in weight and size.[9][10]

Outdoor cannabis cultivation

Guerrilla cannabis plot in a forest clearing
Aerial view of guerrilla cannabis plot

Cannabis can be planted outdoors under the Sun, either on natural soil or in pots of pre-made or commercial soil. Of course some strains are better than others for outdoor cultivation. One strain is not the same as the other and some is just more suitable for your garden than others. This can of course depend on different conditions, variables and aspects. Outdoor marijuana strains, like most other strains, can be bought basically anywhere and there are hundreds of different cannabis strains that are bred for outdoor growing, or at least claimed to be so. A lot of these outdoor cannabis seeds are simply copies of other already existing strains or seeds and have just been given a different name or a nice and interesting sounding description.[17]

To generate optimum quantities of THC-containing resin the plant needs a fertile and long hours of daylight.This means that for that THC production outdoor growth occurs optimally anywhere within 35° of the equator. Typical growing regions include Mexico, Nepal, Northern India, many parts of Africa, Afghanistan, California and Australia.

In most places of the subtropics, cannabis is germinated from late spring to early summer and harvested from late summer to early autumn.

Outdoor cultivation is common in both rural and urban areas. Outdoor cultivators tend to grow indica-based strains because of its heavy yields, quick maturing time, and shortness. Some growers prefer sativa because of its clear-headed (cerebral) high, better response to sunlight, and lower odor emissions.

One can cultivate on his own property or practice guerrilla farming i.e. plant cannabis in remote areas such as forest clearings or mountain cliffs and visit rarely. However, such a method is prone to ripoffs – so much so that some ingenious growers even attach pots to trees to decrease this possibility.[18] Guerrilla growing has given birth to the activist movement Operation Overgrow, where the plant is grown with the explicit purpose of introducing the cannabis plant into the natural ecosystem.

For outdoor cultivation, growers choose areas that receive twelve hours or more of sunlight a day. In the Northern Hemisphere, growers typically plant seeds in late May or early June to provide plants a full four months of growth. Harvest is usually between mid-September and early October. In North America, northern locations are preferred (North Coast of California and British Columbia being particularly notable), but southern locations (such as Maui, Hawaii) are also known to be good producers.[citation needed]

Where local laws do not permit growing cannabis, cultivators sometimes grow in forests or rugged and rural areas where the local population is unlikely to find the crop. Cannabis is also grown hidden by a crop that is taller, such as maize. This is reported by the United States government to be common in the midwestern states.[citation needed] Bamboo and elderberry are also used as camouflage companion plants.[citation needed]

Some government agencies, including the Drug Enforcement Administration (DEA), have claimed that in State and National Parks people have been injured by cannabis farmers protecting their crops using booby traps; no arrests or convictions for this had been made as of 2007.[citation needed]


Often, simple camouflage techniques can avert detection, such as mixing cannabis plants with other bushy, leafy species. Plants started outdoors late in the season do not grow as tall, attracting less attention when placed next to plants of similar or taller stature.

A common technique used by many outdoor growers is to dig a hole and put a potted plant in it. This can reduce a plant's height by at least a foot, reducing visibility to neighbors, visitors and guests. Also, some growers top the plant when it is only 12 inches (30 cm) high, and grow the 2 tops horizontally along a trellis. When using this technique, it is unlikely the plant will grow to be over 3 feet (1 m) tall.

Law enforcement agencies often monitor certain wider areas, particularly areas of countryside with a significant history of outdoor cannabis cultivation. In helicopters, they use infrared cameras and other equipment that can detect cannabis by measuring the heat and reflective signature of the vegetation below. Cannabis has higher reflectivity at certain wavelengths than other rural crops, such as corn. Law enforcement agencies have found that the use of this technology has become necessary in their detection efforts because many growers hide cannabis among other plants, making detection with the naked eye difficult even from the air. These techniques are effective and difficult to defeat because a plant's reflective signature is difficult to change or mask. It has been said[who?] that if the cannabis plant is planted by a pine or cedar tree, the heat from the tree overlaps the cannabis plant heat, making it harder to detect from helicopters, although cedar trees turn the soil acidic due to the low pH of pine needles

Indoor cannabis cultivation

Indoor Cannabis cultivation.

Cannabis can be grown indoors in a soil-like medium under artificial light, adding fertilizer when the plants are given water. Cultivating cannabis indoors is more complicated and expensive than growing outdoors, but it allows the cultivator complete control over the growing environment. Plants of any type can be grown faster indoors than out due to 24-hour light, additional atmospheric CO2, and controlled humidity which allows freer CO2 respiration.

Plants can also be grown indoors through the use of hydroponics.[19][20]

To grow plants indoors, a growing medium (e.g. soil or growing substrate), water, nutrients, light and air need to be supplied to the plant (with the exception of aeroponic cultivation, in which case a growing medium is not required).

Supply of light

To determine the appropriate lighting (and the best lamp to use), the specific needs of the plant must be considered, as well as the room size and ventilation. To arrange optimal lighting, the lighting present in the plant's natural environment must be imitated.[21] For example vegetables grow best in full sunlight, which means that as much light as possible must be supplied to grow cannabis indoors (high intensity discharge (HID) lights such as high pressure sodium (HPS) and metal halide (MH) are preferred. Fluorescent lamps can also be used). Incandescent and mercury vapor lighting are not recommended for use in cannabis cultivation.

Cannabis plants also require both dark and light photoperiods, so the lights need a timer to switch them on and off at set intervals. The optimum photoperiod depends on each plant (some prefer long days and short nights and others preferring the opposite, or something in between).

Most plants grow under most light spectra, but always prefer a full spectrum light. A test done by Ed Rosenthal[citation needed] found that when a room was set up using both high pressure sodium (HPS) and metal halide (MH) lamps the plants in between the two lights did better than those under MH alone but not as well as those under HPS. However, certain plants (as cannabis) can be grown successfully under both types of light. MH is used for vegetative phase of growth, as it encourages short inter nodes (distance between sets of leaves), and inhibits cell elongation, creating a shorter, stockier plant. Metal halide lamps produce more ultraviolet radiation than high pressure sodium lamps, which may play a role in increasing the flowering (and for certain plants as cannabis the amount of working substances as THC) produced by the plant. High pressure sodium lamps trigger a greater flowering response in the plant and are thus used for the second (or reproductive) phase of the growth, or they are used by those people who only wish to purchase a single lamp.[22] If high pressure sodium lamps are used for the vegetative phase, plants usually grow slightly more quickly, but also have longer inter nodes, and may be taller.[23]

Recent advancements in LED technology have allowed for diodes that emit enough energy for cannabis cultivation. These diodes can emit light in a specific nanometer range, allowing for total control over the spectrum of the light. LEDs are able to produce all of their light in the PAR range. One major short coming of LED’s remains their lack of intensity. Due to this lack of intensity LED is only able to excel at growing plants in the vegetative stage of growth, or when flowering with extremely small canopies (micro grows).

LED grow lights are still considered an experimental technology in cannabis cultivation. Due to their high cost and low light output they remain unused by the commercial grower. The market remains flooded with cheap quality LED lights that do not produce yields comparable to what growers are accustomed to. Many companies are using single watt LED chips, which have notoriously produced low yields and wispy results. When considering purchasing any grow light, one should carefully examine both the spectrum and the intensity of the light, and try to find results from similar grows using that light.

LED panel light source used in an experiment on plant growth by NASA. Pictured plant is a potato plant.

According to the inverse square law, the intensity of light radiating from a point source (in this case a bulb) is inversely proportional to the square of the distance from the source. So if an object is twice as far away, it receives only 1/4 the light. This is a serious hurdle for indoor cannabis growers, and many techniques are employed to use light as efficiently as possible.

Reflectors are often used in the lamps to maximize light efficiency. Plants or lights are moved as close together as possible so that they receive equal lighting and that all light coming from the lamps fall upon the plants. Maximum efficiency can be obtained by creating a slightly concave canopy such that the periphery and center of the canopy are both at the optimum distance from the light source. Often, the distance between lamp and plant is in the range of 0.6 m (2 ft) with high pressure sodium lamps, to 10 cm (4 in) with other lamps, such as compact, large and high-output fluorescent lamps. With proper cooling any light type can be moved extremely close to plants to combat the inverse square law, but there are reasons to keep some distance from the canopy regardless of heat concerns; excessive light can cause bleaching of the plant material and the total canopy area contacted by light is decreased as the source is moved closer. Maximum efficiency should be obtained by maximizing the average light intensity (measured in PAR watts) per square foot times the number of square feet of plant matter contacted. Some cannabis cultivators cover the walls of their grow-room with some type of reflective material (often Mylar or Visqueen), or alternatively, white paint to maximize efficiency.

One commonly used covering is 150 µm (6 mils) PVC plastic sheeting that is white on one side and black on the other. The plastic is installed with the white side facing in to the room to reflect light, and the black facing the wall, to reduce fungus and mold growth. Another common covering is flat white paint, with a high titanium dioxide content to maximize reflectivity. Some growers consider Mylar sheeting to be very effective when it lines grow room walls, along with Astrofoil (which also reflects heat), and Foylon (a foil-laminated, reinforced fabric). Because of the inverse square law, however, and the distance the light must travel to contact the reflective material and then bounce back to contact the plant material, this efficacy is highly debatable.

Control of the atmosphere

When growing indoors, the cultivator should maintain as close to an ideal atmosphere inside the grow-room as possible. The air temperature should be maintained within a specific range, typically with deviations no larger than 10 °C. with a cooler night and warmer day. Adequate levels of CO2 must be maintained for the plants to grow efficiently. It is also important to promote vigorous air circulation within the grow room, which is usually accomplished by mounting an extraction fan and one or more oscillating fans.

Assuming adequate light and nutrients are available to plants, the limiting factor in plant growth is the level of carbon dioxide (CO2). Plants grown with supplemental carbon dioxide grow more quickly, have larger stomata (Pores), and can use more light. According to Ed Rosenthal, however, heat must be increased from 75 degrees F to between 80 and 85 degrees F in order to fully utilize the increased CO2 concentration (the increase in heat allows for a faster metabolic rate). Ways of increasing carbon dioxide levels in the grow-room include: bottled carbon dioxide, carbon dioxide generators, a milk jug and yeast solution (in which yeast grows in a container thereby emitting CO2), a baking soda and vinegar mixture in a container, or dry ice.[24]

Certain plants (e.g. most strains of cannabis) emit a distinctive odor during their reproductive phase. This presents difficulties to those who are cultivating in places where it is illegal, or for growers who may prefer discretion for other reasons. The most common way of eliminating odor is by pulling odorous air through a carbon filter. Many cultivators simply attach a large carbon filter to their air extraction system, thereby filtering any smell before the air is expelled from the grow-room. Another way of eliminating odor is by installing an ozone generator in the extraction ducting. The air is forced past the ozone generator by the extraction fan, and the odorous air is neutralized as it mixes with the ozone; however the cultivator must ensure that the air is thoroughly mixed before it is expelled outside, lest some odor escape. Care must be taken to prevent excessive ozone concentrations in the garden itself, or where it might be inhaled by the grower or his/her family. Ozone itself has a distinctive smell and is harmful to living things, although the molecule breaks down quickly (20 minutes to an hour) in atmospheric conditions.

Indoors there are numerous configurations that people utilize to grow quality cannabis. Some growers will convert an entire room or closet, making it devoted to growing cannabis. A relatively new configuration involves the use of grow tents. These are plastic or metal framed tents which are covered in a strong flexible reflective plastic and have light proof zipper doors. Tents come in all sizes and many already have holes for exhaust fans/ducting as well as mounts for HID lights.

Some growers will construct grow cabinets made out of an old refrigerator, cabinet, dresser drawer or similar.


Indoor cannabis plant during flowering

Indoor growing has become increasingly common over the past decade because of the increased availability of equipment, seeds and instructions on how to cultivate. So-called grow-ops (growing operations, often located in grow houses) are seen by many marijuana enthusiasts as a much cheaper way to gain a steady, higher-quality supply of cannabis. On a larger scale they have proven a viable commercial venture, with some law enforcement agencies finding grow-ops large enough to yield several kilograms of cannabis. More expansive grow-ops are generally more susceptible to detection than smaller operations.

Because individual grow light power generally ranges from 250 watts to 1000 watts or more and because the lights remain lit for a long time each day, differences in utility bill costs are a significant security issue. It is not uncommon for power companies to work with law enforcement if they see a significant increases in power usage relative to a household's previous electricity costs or if power is being stolen by bypassing the meter. Employing energy saving methods is a common way to alleviate this, for instance; switching off light bulbs when leaving rooms, purchasing energy efficient appliances, using TVs or computers less, buying lower power light bulbs and so forth.

Some plants (e.g. cultivars of Cannabis sativa subsp. indica), can give off strong odors as they grow, resulting in detection of illegal growing operations. Growers frequently use carbon scrubbers and ventilation to control odors. This typically involves forcing air from the grow room through a device containing activated carbon, then venting it outdoors. Others use an ozone generator. Ozone reacts with odor molecules in the air, permanently eliminating them. However, ozone can build up to levels that may be hazardous both for grower and plant. As a last resort, keeping windows firmly shut and using strong air fresheners can control smells. Checking outside to see if any smells are emanating from indoors is often a necessary precaution, as many growers become acclimated to the smell, and fail to realize just how pervasive the odor may be. Many store plants in more isolated areas such as a basement or attic to prevent smell detection. Another less common solution is to simply grow a strain with a weaker odor.

Storing plants and lights away from windows and areas that visitor may see is also common, as is keeping the plants in an attic or basement. Some growers, finding this impractical, may cover windows with light-resistant materials. This can solve the problem of escaping bright light but may arouse suspicion amongst neighbors and local residents.

Many cultivators face the risk of fire. Fires normally originate from faulty electrical equipment or wiring. Shoddy fixtures and sockets, improperly grounded equipment, and overloaded circuit breakers are some of the most prevalent causes. Because of the large amount of electricity needed for large-scale cultivation, old or damaged wiring is prone to melt and short. Some commercial growers steal power to hide electricity use, and many do not ensure that their wiring is safe. Many growers adapt light cycles so that the lights are on when they are home and off when they are away.

Another fire hazard is plants making contact with hot HID bulbs. Growers using fluorescent bulbs with reasonable air circulation do not have this problem. Word of mouth can be as much a threat to growers as any of the above issues. Often, a few sentences of conversation overheard can result in a tip-off and thus speedy detection. It is for this reason that many growers are reluctant to talk about their cultivation.

Housing damage

For houses used as grow-ops, the interiors may have received significant structural, electrical and heating system modifications not in accordance with applicable building, natural gas and electrical codes, such as overloaded existing electrical system or a bypass circuit to avoid paying for the electricity required to power the high intensity light bulbs and fans, disconnected furnace venting, or holes in floors and walls for increased airflow. These changes replicate warm, humid climates where hybrid plants flourish and produce high potency cannabis. Such modifications may result in considerable structural damage. Cultivation over a period of time may lead to moisture and toxic mold.[25][26]

Grow-op homes appear to be maintained in their normal fashion on the outside. Nonetheless, there are plenty of tell-tale signs, such as occupants often avoid their neighbors, a "beware of the dog" sign, and melted snow in the winter (because of the higher-than normal heating to cultivate these plants).[27]

One of the largest such examples was masterminded by a Markham, Ontario real estate agent, John Trac, who turned 54 rented houses into grow-ops. He was convicted and imprisoned, but his second-in-command, Jennifer Wu, remained at large. Electricity suppliers estimated the value of the electricity stolen and required that it be paid for before reconnecting houses.[28][29]

Contractor and television presenter Mike Holmes said that while houses formerly used for growing cannabis could be bought very cheaply from banks or other owners, repairs and remediation could cost around $100,000 CAD, which may exceed price savings. Holmes noted that in one of his past jobs on Holmes on Homes, he and his crew gutted the entire house after discovering it was a grow-op.[30][31]

In some municipalities, after the police raid a grow-op house they are required to contact the municipality to ensure that it is put back in good condition before being offered for sale, while real estate agents and sellers may be required by law to disclose that the home had been a grow-op. Home inspectors routinely fail to detect tell-tale signs that a house had been used as a grow-op.

Harvesting, drying and curing

Close-up of a female cannabis bud in flowering stage. White trichomes can be seen coating the surface, which darken as flowering progresses.

There may be different goals when harvesting a plant :

When the goal is to smoke the harvest, a bud production focused cultivation (called sinsemilla) is preformed. A typical indicator that a plant is ready to be harvested for smoking, is when 2/3 of the pistils have turned from clear or white to reddish brown. In general, harvesting consists of drying and curing. Curing is essential for the even distribution of moisture in the buds.

A popular method is the following, will alternate curing and drying, such as:

..and repeat until product is deemed ready

Usually, In 3–4 days buds are ready for consumption.[32]

Cannabis buds are typically harvested when fully ripe. Generally, ripeness is defined as when the white pistils start to turn dark yellow, orange, light to mid red, etc. and the trichomes, "crystals", barely begin to turn milky from clear.[33] These trichomes can range from completely clear (generally deemed underdeveloped), to amberish-red. Ideally, professionals use a decent power magnifying glass, a brix meter to measure "sugar" content, and a microscope. The potential seed pods swell with resins usually reserved for seed production, thus improving the quality of the buds (called colitas, Spanish for "little tails"), which swell to form full "colas" (Spanish for "tails"). Harvesting slightly early will maximize the THC content. Harvesting later reduces the THC content and maximizes the sleep inducing effect desired by some medical users.


The plants are dried at room temperature in a dark space. It is actually optimal to keep the temperature between 60 and 70 degrees F because many terpenoids (molecules that are partially responsible for the psychoactive effects but also largely responsible for the odor of the plant) evaporate at temperatures beyond 70 degrees. This process can take from a few days to two weeks, depending on the size and density of the buds and the relative humidity of the air. Humidity should be kept between 45% and 55% humidity. Higher humidity will create a mold and mildew risk, while lower humidity will cause the material to dry too quickly. If the plant material dries too quickly, some of the chlorophyll will fail to be converted to a different chemical form which will result in a sub-optimal taste and a harsher smoke when combusted and inhaled. Stable temperature preserves cannabinoids well. Some believe flowers are hung by their stalks, allowing the internal fluids of the plant to remain in the flowers. Others believe the cut stem is simply a handy non-sticky place to hang the plant from. Roots are removed, and when the stems in the middle of the largest buds can be snapped easily, the plant is dry enough to be cured. Drying is done in a dark place, as THC resins deteriorate if exposed to light and the degradation product CBN forms, significantly altering the cannabinoid profile of the dried flowers.

Drying plants is not generally considered as that risky by novice indoor growers of cannabis who would like to assume that they have gotten safely to the end of their "grow" by the time they are harvesting their plants. However, generally speaking most will underestimate the sheer scale of odour produced cutting down ("cropping"), moving and hanging plants to dry. Indoor growers in areas where cultivation is illegal may consider this an obstacle in their overall efforts as the first three days of drying produces very large amounts of discernable odour (organic molecules) which the grower himself/herself may be de-sensitised too. These will be evaporating and likely discernable to others anywhere in the vicinity of the general area. In populated areas consideration of containment & concentration (i.e. filters) of odour molecules may be employed to reduce risk. In less populated areas with good air movement dissilution and dispersal techniques for odour management may be employed i.e. ventilation from high points such as a chimney or roof vents. Whatever, method is to be employed newbie growers in illegal areas would do well to not underestimate the sheer volume of organic molecules being dissipated into the air when harvesting or "cropping" grows.


The curing process continues breaking down sugars and helps develop taste and smoothness of smoke. Usually, the dried product is packed (not compressed) into airtight glass canning jars. Initially, the product is checked periodically (every few hours) to make sure it was properly dried and has not re-moistened itself. After several days, when the product is dried to satisfaction, the jars are sealed off and opened just once a week. Curing is highly varied—the minimum is usually two weeks. Some growers even cure as long as six months, while others do not cure at all. As with tobacco, curing can make the cannabis more pleasant to smoke. For the same reasons as when drying, curing jars are stored in a cool, dark place. Failure to vent the jars causes moisture that leads to quick mold build up.[34]

A recent method of curing is called water curing. This method is quicker and can improve a lower quality product. Using this method, nutrients can be fed to the plants right up until they are harvested because the water flushes out harmful chemicals (such as the ones used to feed the plants) as well as proteins, sugars, pigments and some resins. This also increases the THC to weight ratio[35] though many believe the finished product is not as attractive as using a standard dry and cure method.

Tincture. Ethanol is used to extract cannabinoids from the cannabis plant (THC is soluble in alcohol). The extraction process takes longer, but results in an edible product. Cannabis stems, leaves and buds can all be used. The resulting mixture can be eaten straight, mixed with food or even smoked. Many smokers prefer to dip cigarettes in the mixture, which allows them to smoke in public without detection. Contact with direct flame causes this liquid to lose its THC content (THC vaporizes at 157 °C (315 °F ). Smokers usually heat the liquid and inhale the vapors through a straw.


Hashish can be expensive but like everything else in cannabis cultivation, it can be an investment that pays for itself. The small leaves surrounding the flowers, the "trim leaf" are usually coated in a large amount of trichomes, a leaf structure usually containing more THC than the flowers, that can be collected many ways, including dry sift(usually you should use a fine steel or silk screen), where plant material is rubbed against a screen that allows only trichome sized material through. Put a mirror under the sifting device to catch all the trichromes or "Kif". You can also use Bubble Bags or other kinds of filter bags. With this method, trichomes on trim leaf are frozen for 24 hours then agitated in ice water in a 5 gallon bucket lined with a succession of bags having decreasing screen sizes that capture the plant matter and allow the trichomes to pass down to the bottom bag where they collect into a wet paste. The large fan leaves may also have a minor amount of trichomes to be collected. The paste is pressed between its screen and a clean absorbent towel to extract water from the paste until it has the texture of clay. The clay (hash) is then shaped and smoked. This type of processing creates hashish called "bubble hash". The dry sift and so-called "bubble bag" methods can also be combined in a very efficient dry-ice sifting process; the leaf material is thrown into a bubble bag (or otherwise properly sized silk screen bag) with dry ice. The bag can then simply be hand shaken over a mirror to obtain a very pure concentration of trichomes. These can be stored as is or subsequently pressed into "blonde hash".

"Bubble hash" is so named because of bubbles released (sometimes) as it burns. Pre-freezing the trim for 24 hours reduces bubbling by stiffening and hardening the trichomes. This prevents the trapping of water molecules when the trichomes separate from leaf matter (imagine icicles breaking off a frozen tree branch). The lack of using pre-frozen trim reduces the quantity of trichome separation and it increases the likelihood of "burning bubbles". These bubbles are interesting to see but totally harmless.

Hash is generally more potent than the flowers from the same plant.

Hash oil

Allowing the ethanol in a tincture to evaporate makes hash oil. However, ethanol, should never be evaporated with direct heat or near an open flame. The resultant hash oil is often very strong in terms of THC content (depending on parent material), and can be then smoked. Delta 9 THC is most strongly soluble in petroleum ether and less so in ethanol. Adding petroleum ether to tincture extracts D9 THC, and leaves water soluble chemicals in the ethanol (certain cannabinoids, proteins, chlorophyll, etc.)

Brick weed

Paraguayan Brick weed known as Piedra.

Brick weed is a method of cannabis cultivation that consists in drying the bud for a one or two days and pressing it with an hydraulic press, compacting the whole plant (bud, stems and seeds ) into a brick, hence the name brick weed, This cultivation method is mainly used in the top cannabis producing countries like Mexico and Paraguay for drug trafficking.

Brick weed has low THC level, a consequence of the way it is processed and because of the humidity in the plant that develop Anaerobic organisms and fungus that make the plant particular smell like ammonia.[36]


Outdoor growers are likely to confront issues regarding pests. In any case (indoor or outdoor), experienced growers recommend caution when using chemical pesticides, for they may have toxic effects on the environment, the plants themselves and in turn cannabis consumers. As a general rule, experts mandate the deployment of pesticides clearly marked as "safe to use on food crops". Substances proven to induce little or no harm include:

Indoor growers also have problems with pests, usually caused by the grower or a pet bringing them in from the outdoors. If caught too late, eradication of many destructive insect species indoors may be impossible until all infected plants are removed from the space and sterilization methods employed.

Advanced cultivation methods

The legal status of cannabis has led growers to implement novel cultivation methods for indoor growing with lamps to avoid aerial surveillance.[37] These methods include:

  1. using a water or air-based growth medium (known as hydroponics and aeroponics respectively)
  2. the use of homemade, organic composted fertilizers
  3. training and trellising techniques such as Screen of Green (also known as SCROG), Sea of Green (also known as SOG) "Super cropping" and LST super cropping; and entire systems and methods such as the NIMBY no-dump method, Hempy Bucket, and the Krusty Freedom Bucket methods. Research into the production of cannabis for the drug Marinol and other more profitable and marketable forms of cannabis based medicines has further pushed the envelope of cannabis cultivation in all forms of laboratory, both public and private.

The emphasis on advanced cultivation techniques, as well as the availability of hybrid strains (with names like Northern Lights, Master Kush, NYC Diesel), is believed to be a factor in the increase in the overall quality and variety of commercially-available cannabis over the past few decades. The internet in particular has brought together widely diverse genetics from around the world through trading and purchasing. However, well-grown heirloom strains (e.g. island sweet skunk, fruity Thai etc.) are used to produce 1 gram per watt harvest.


In contrast to the "Screen of Green" method, Sea of Green (or SOG) growing depends on the high density of plants (as high as 60 per square meter) to create uniformity in the crop. In this technique, which is often grown in hydroponic media, only the colas of the plants are harvested. Containers are used to enforce the geometric distribution of flowers and plant material, as well as their exposure to lighting and atmosphere. Sea of green is popular with commercial cultivators, as it minimizes the amount of time a plant spends in vegetative stage, and allows very efficient light distribution, keeping the plants much closer to the lights than when grown to full size.


SCROG, short for SCReen Of Green, is an advanced training technique for cultivating Cannabis, mainly indoors. Closely resembles SOG (or Sea Of Green) with the difference being that SCROG uses extensive training to produce the same field of bud effect with only one plant. Medical growers may find this a helpful technique to maximize harvest if they are only allowed a certain number of plants. A screen such as chicken wire is hung over plants so that the tips of branches are kept at the same level. This allows even light distribution to all of the nodes/bud sites. Once the flowering stage begins, the flower tips reach through the wire and are at relatively equal distances from the light source.

Light attenution with distance: Light intensity follows the inverse square law[38]: it decreases as the square of the distance from the source. Cannabis growers try to optimise use of light. The lower branches of an untrained plant do not produce as well as the upper branches, as they are further from the light. The SCROG method puts basically the whole plant on one horizontal plane, allowing all bud sites to receive nearly maximum light, increasing productivity.

Vegetative state: The plant should remain in the vegetative state until 70 to 80 percent of the net is full.[39] As a branch reaches three to four inches above the wire it is pulled back under the wire and so trained to grow horizontally until flowering. Because of the amount of plant required to fill the net, the vegetative period may require longer than normal to be ready for flowering.

Timing: Timing is vital to the success of a SCROG grow. If the net is not full at harvest, valuable space has been wasted. If the net is too full then the buds will be too crowded to develop properly. Knowing how a plant grows can help to visualize when to flower for maximum effect.


Example of a small hydroponic system for cannabis cultivation

Hydroponic cultivation generally occurs in greenhouses or indoors, although there is no practical obstacle to growing outdoors. In general, it consists of a non-soil medium exposed to a nutrient and water flow.

There are many types of hydroponic systems. If the nutrient solution floods the loose growing medium and recedes for aeration, this is an ebb and flow or flood and drain system. Systems that gradually drip solution onto the medium are drip systems. Systems that intermittently spray roots floating in air are called aeroponic systems. If aerated water runs down a channel lined with a film of rooting medium, this is a nutrient film technique system. A series of tubes intermittently running high flow nutrient solution into the tops of growing containers use a top feed system. Aquaponics, another growing method that is gaining popularity, employs the use of fish water and recirculates that water from the fish holding tank to the growing bed.

Hydroponic systems greatly increase aeration of plant roots, and increase control of nutrient uptake. Hydroponic systems are decidedly more difficult to operate for the amateur or hobby grower, as over-fertilization is common, because there is no soil to act as a nutrient buffer. For this reason, many growers now use coconut fiber as a soil-less medium because of its high drainage and buffering capabilities that make it almost impossible to over-fertilize. Additionally, if a hydroponic system fails, the crop has a high probability of dying as the roots rapidly dry out (this is especially true of aeroponic systems).

There is now a new breed of hydroponic configurations such as the Omega Garden, the B-Pod and the EcoSystem Vertical Growing System that use circular designs to maximize efficiency. This consists of plants being placed or, in the case of the Omega Garden, revolving around a central light that makes maximum use of the light output.

Difference between Cannabis indica and Cannabis sativa

Cannabis indica may have a CBD:THC ratio 4–5 times that of Cannabis sativa. Cannabis strains with relatively high CBD:THC ratios are less likely to induce anxiety than vice versa. This may be due to CBD's antagonistic effects at the cannabinoid receptors, compared to THC's partial agonist effect. CBD is also a 5-HT1A receptor agonist, which may also contribute to an anxiolytic effect.[40] This likely means the high concentrations of CBD found in Cannabis indica mitigate the anxiogenic effect of THC significantly.[40] The effects of sativa are well known for its cerebral high, hence used daytime as medical cannabis, while indica are well known for its sedative effects and preferred night time as medical cannabis.[40]


Selection of mother plants

An important factor while cultivating photoperiod independent (non-autoflowering) cannabis is selecting the best genetics for one's crop. This is frequently done by selecting one or more known strains, or strains with preferred genetics (in the case of cannabis, one might use seeds from a batch that was particularly enjoyed), and then growing a number of the seeds to find out which exhibit the characteristics most desirable to the cultivator. These genetics should typically yield at least 1 gram per watt per month of flower.

Plant characteristics generally selected for include:

A cultivator decides which plants exhibit the most desirable traits, and takes a cutting that is grown to maturity but never allowed to flower. This plant is a mother, and can be kept for years, producing thousands of clones genetically identical to the mother.[41]

Autoflowering strains

Autoflowering cannabis strains, also known as day-neutral cannabis are a relatively new development for the home cultivator. These autoflower strains are usually crosses that contain high percentages of well known photoperiod strains and contain only the autoflowering characteristics of C. ruderalis. The plant produced from an autoflowering seeds will transition from a very short vegetative period, usually 2 to 3 weeks from germination, into flowering regardless of photoperiod. The result is that no separate vegetative and flowering lighting environment are needed. Flowering is dependent on the plants age not the time of year or ratio of light to dark hours. Autoflowers will finish from seed in 12/12, 18/6, 20/4 or even 24/0 lighting. The new thing on the market of commercial Cannabis cultivation are autoflowering Strains. By crossing of the Cannabis ruderalis with c. sativa and c. indica strains many cultivators have created hybrids with properties from both sides of these families.

The first 'autoflowering cannabis seed' which came on the market was the Lowryder #1. This was a hybrid between a cannabis ruderalis, a William’s Wonder and a Northern Lights #2. The genetics of the ruderalis was still highly present which made for a very low yield and little psychoactive effect.

The Lowryder #2 was later introduced by ´The Joint Doctor´.[42]

To grow plants indoors, a growing medium (e.g. soil or growing substrate), water, nutrients, light and air need to be supplied to the plant.[43]

A few experienced growers are strongly opposed to the proliferation of these genetics for a variety of reasons. Online seed vendors offer carry increasing numbers.[citation needed]

Several online cannabis cultivation forums have added subforums dedicated to growing autoflowers while members of other sites have broken off and created entirely new forums completely devoted to autoflower growing. Examples include the sub forum on and

Feminized seeds

Instability of gender is a desirable trait in the wild, where reproduction is the most urgent goal. In cultivation, gender predictability is more helpful, because female plants that have not been pollinated are the most productive. It is possible to use a combination of cloning and "shocking" plants to get them to produce feminized seeds that reliably produce female offspring. A clone retains the same sex throughout its life, so the clone of a female plant is also female.

Environmental stresses sometimes create pollen bearing male flowers on female plants—known as hermaphroditism or 'hermying'.

A method used by organic growers and promulgated by the Cannabis breeder Soma, is called 'Rodelization', or letting un-pollinated female plants live several weeks longer than the normal harvest time. In such plants a hermaphroditic trait self-expresses in an effort to continue the genetic line.

Some vendors of feminized seeds assert that hermaphroditic "parents" do not create reliable feminized seeds, since the offspring may retain this tendency. Others believe that this method utilizing auto-hermaphroditic traits is offset by grower observations that the tendency to auto-switch sex is not great in plants grown from seeds made this way, and that it occurs naturally without effort on the part of the cultivator.

Colloidal silver (commonly abbreviated CS) suppresses ethylene production in bud sites, stimulating male characteristics. Spraying selected leaves, branches and – in cases where a large amount of seed is desired – whole plants with colloidal silver solution has become a preferred method of obtaining feminized seeds. Most plants treated with CS will turn intersex within 2 weeks of triweekly treatment, producing viable pollen within 4. Gibberellic acid has also been used for the same purpose, but it is harder to find than colloidal silver and can be difficult to dissolve into solution. One method of obtaining colloidal silver utilizes a small direct current power supply and two pieces of solid silver jeweler's wire, or silver coin.[44]

Some cultivators claim that the genes responsible for hermaphroditism are present and may be expressed under stress from any of the above methods and that once expressed, this characteristic passes to seeds regardless of what activated it. This view, in large part, is incorrect, as a random half of the genes present in each of the parental plants passes to the next generation, regardless of whether the genes that contribute to hermaphroditism were induced by stressors or not. This widely accepted Mendelian model of inheritance (Mendelian inheritance) does allow for genetic mutations that have occurred in the germline (Germline) of an organism to be passed on to any offspring, but this process applies to all DNA sequences, not just those contributing to hermaphroditism. The inheritance of acquired characteristics (Lamarckism) that are not directly coded in the DNA sequence (Epigenetics) has recently received much attention in the area of genetic research and could possibly explain any anecdotal evidence for increased hermaphroditism in the offspring of plants induced to a hermaphroditic state. However, a more likely explanation is that by propagating plants easily induced to hermaphroditism by environmental stressors, the frequency of genetic elements contributing to this trait is increased by artificial selection following traditional genetic models of inheritance. Some theories suggest it is possible to selectively breed hermaphroditic cannabis to express the female flowering before the male flowering occurs, though this kind of selective breeding is beyond the capabilities of most cultivators.

Hybrid vigor

When crossing two strains of cannabis (or two of any plant), the resultant hybrid may possess what is called hybrid vigor. In general, this produces a plant that is healthier, stronger, or quicker growing than its predecessors. Sometimes, in the case of a plant that has been brought back from fruiting (fruition, as mentioned above), it may be beneficial to cross it back with another (close) relative, in the hopes that it becomes invigorated.[45]

Caution should be exercised, as one does not always attain a beneficial cross with hybridizing.

Vegetative propagation (cloning)

Like most plants, cannabis has the potential for vegetative propagation, with the most common and simple method being cutting. Cutting is characterized as a cloning method, since the derived plants have identical DNA to the "mother plants".[46]

Under appropriate environmental conditions, a cut part of the cannabis plant, typically from the main stem or a lateral branch, has the ability to produce roots and develop into a whole new plant (the clone), genetically identical to the mother. In cannabis, the production of roots may take anywhere from 5 to 21 days.

The oldest method of cannabis propagation is water cloning. Used for nearly as long as agriculture has been a part of human development, one simply sticks the cut end of clone (cutting) into a small body of water like a glass or bowl and waits. Water cloning can take longer to show roots, but is a truly natural way to propagate any plant that is able.

Marijuana growers often root clones in peat pellets (compressed peat moss) or in rock wool. Another technique that has become popular for rooting clones is aeroponic cloning.

The main steps of hormonal cannabis cutting are as follows:

  1. Part of the main stem or lateral branch up to 20 cm long is dissected in a non-vertical manner. The bottom 2/3 of leaves are removed.
  2. The cutting is brought to contact with rooting hormone, according to instructions, to promote root growth and inhibit fungal infection.
  3. The cutting is placed in an appropriate initial medium such as common soil, compost, perlite, vermiculite, peat moss, sand, rock wool, oasis foam or a combination of those. The initial medium is kept moist and high humidity is maintained in the surrounding air. Elevated humidity levels slow the transpiration rate (water loss from leaves) and prevent the cutting from drying out. Mold is a common hazard due to the higher humidity and stressed cutting. During this phase, the temperature is kept relatively low (25 C) and direct light is avoided so that the cutting does not dry out. The production from the slower photosynthesis is put into root production.
  4. After initial root development is evident (usually within three weeks) the cutting is ready to be transplanted into its final grow medium. The high humidity environment is no longer necessary.

See also


  1. ^ cannabis
  2. ^ Medical cannabis
  3. ^ Legality of cannabis
  4. ^ Legality of cannabis by country
  5. ^ Cannabis – Wikispecies. Retrieved on 7 August 2011.
  6. ^ Cannabis sativa L. – Encyclopedia of Life. Retrieved on 7 August 2011.
  7. ^ American Journal of Botany (2004). "A chemo taxonomic analysis of cannibalized variation in Cannabis (Cannabaceae)". American Journal of Botany 91 (6): 966–975. doi:10.3732/ajb.91.6.966. PMID 21653452. Retrieved 8 October 2006. 
  8. ^ Small, Ernest (1975). "American law and the species problem in Cannabis: Science and semantics". Archived from the original on 19 April 2005. Retrieved 8 October 2006. 
  9. ^ a b c Greg Green (2001). The Cannabis Grow Bible (4th ed.). p. 47. ISBN 1-931160-17-1. 
  10. ^ a b Jorge Cervantes. Marijuana Horticulture (5th ed.). ISBN 1-878823-17-5. 
  11. ^ The Marijuana Grower's Guide (1998) by Mel Frank and Ed Rosenthal, typed by Ben Dawson, revised 1992
  12. ^ "Greg Green" The Cannabis Grow Bible, 4th edition (2001), page 153,154
  13. ^ "Greg Green" The Cannabis Grow Bible, 4th edition (2001), page 164
  14. ^ How to grow weed ", Grow Weed, 26 September 2010
  15. ^ "Vegetative stage lighting requirements.". 
  16. ^ "Marijuana Botany – An Advanced Study: The Propagation and Breeding of Distinctive Cannabis – Robert Connell Clarke". Retrieved 16 March 2009. 
  17. ^ Cannabis Magazine 2012.Best outdoor cannabis seeds.
  18. ^
  19. ^ "Cannabis cultivation using hydroponics". Retrieved 16 March 2009. 
  20. ^ "How to grow hemp using hydroponics". Retrieved 16 March 2009. 
  21. ^ "Determining appropriate lighting". Retrieved 16 March 2009. 
  22. ^ toon (1 July 2008). "Cannabis Growing Guide Part 2 – Grow lamps". Retrieved 16 March 2009. 
  23. ^ Lights – High Pressure Sodium AND Metal Halide[dead link]
  24. ^ The CO2 enrichment guide[dead link]
  25. ^ "Houses suffer damage from grow-op activities". The StarPhoenix (Saskatoon). Retrieved 28 April 2011. 
  26. ^ Harvey, Ian (May 2005). "Grow Ops—An Inside Look". Reader's Digest. Archived from the original on 15 April 2005. Retrieved 28 April 2011. 
  27. ^ Marijuana Home Grow Operations. (2009-01-01). Retrieved on 7 August 2011.
  28. ^ Goddard, John (22 December 2009). "Real estate agent jailed, fined M for grow-op scheme". The Star (Toronto). Retrieved 28 April 2010. 
  29. ^ Small, Peter (5 May 2009). "Grow-op king duped 54 homeowners". The Star (Toronto). Retrieved 28 April 2010. 
  30. ^ "Grow Op Cover Up". CBC News. 
  31. ^ [1][dead link]
  32. ^ Ready – Set – Grow (High Times Marijuana Growing Instructional Video)
  33. ^ How to Grow Marijuana: The Basics. Retrieved on 7 August 2011.
  34. ^ Curing Marijuana
  35. ^ grow
  36. ^
  37. ^ Expert tips on growing cannabis. Retrieved on 7 August 2011.
  38. ^ "Inverse Square Law". 
  39. ^ "The Scrog Method". 
  40. ^ a b c J. E. Joy, S. J. Watson, Jr., and J. A. Benson, Jr. (1999). Marijuana and Medicine: Assessing The Science Base. Washington, D.C.: National Academy of Sciences Press. ISBN 0-585-05800-8. 
  41. ^ Cloning Marijuana. Retrieved on 7 August 2011.
  42. ^ "What are autoflowering cannabis seeds". 
  43. ^ "autoflowering seeds". 
  44. ^ How to Easily Produce Your Own Feminized Cannabis Seeds. Retrieved on 7 August 2011.
  45. ^ Marijuana Genetics. Marijuana Genetics. Retrieved on 7 August 2011.
  46. ^ Cloning Marijuana Made Simple. Retrieved on 7 August 2011.

Further reading

External links