This article presents common techniques and facts regarding the cultivation of cannabis, primarily for the production and consumption of its infructescences («buds» or «leaves»). Cultivation techniques for other purposes (such as hemp production) differ.
Cannabis needs certain conditions to flourish.
- Stages of development
- Flowering and fruition
- Outdoor cannabis cultivation
- Indoor cannabis cultivation
- Supply of light
- Control of the atmosphere
- Popularity and extent
- Harvesting, drying and curing
- Organic and inorganic pest controls
- Selection of mother plants
- Vegetative propagation (cloning)
- Music and reception
Soil is required, except for cannabis grown with hydroponics or aeroponics.
- Sufficient nutrients — commercial potting soils usually indicate this as «N-P-K = x%-y%-z%». This indicates the percentages of fundamental nutritional elements, i.e., nitrogen, phosphorus and potassium. Nutrients are often provided to the soil via fertilizers but such practice requires caution.
- A soil pH between 5.8 and 6.5. This value can be adjusted – see soil pH. Commercial fertilizers tend to make the soil more acidic, although manure has a less pronounced effect.
Sun light or grow light can be used.
Nutrients are taken up from the soil by roots. Nutrient soil amendments (fertilizers) are added when the soil nutrients are depleted. Fertilizers can be chemical or organic, liquid or powder, and usually contain a mixture of ingredients. Commercial fertilizers indicate the levels of NPK (nitrogen, phosphorus, and potassium). In general, cannabis needs more N than P and K during all life phases. The presence of secondary nutrients (calcium, magnesium, sulfur) is recommended. Micronutrients (e.g. iron, boron, chlorine, manganese, copper, zinc, molybdenum) rarely manifest as deficiencies.
Stages of development
Very young clones in humidity domes
Germination is the process by which a seed sprouts and a root emerges. Germination in cannabis can occur in as little as twelve hours or can take as long as eight days, depending on the cultivar and environmental conditions. Warmth, darkness, and moisture initiate metabolic processes such as the activation of hormones that trigger the expansion of the embryo within the seed. Then the seed coat cracks open and a small embryonic root emerges and begins growing downward (because of gravitropism), if placed in a proper growing medium. Soon (after 2–4 days) the root is anchored and two oval cotyledons (sometimes called «false leaves» or «seed leaves») emerge in search of light and the remains of the seed shell are pushed away. This marks the beginning of the seedling stage.
Peat pellets are often used as a germinating medium because the saturated pellets with their seedlings can be planted directly into the intended growing medium with a minimum of shock to the plant.
- Scarification (artificial), example: Soaking the seeds in boiled water that is cooled down.
- Stratification (natural simulation), example: Soaking seeds either between wet paper towels, in a cup of water at room temperature, in wet peat pellets, or directly in potting soil.
A very young C. sativa seedling. The tips of the first set of rough leaves are emerging between the two round seed leaves (cotyledons).
The seedling stage begins when the seed coat splits open and exposes the root and cotyledons. It lasts from 1 to 4 weeks, and is the period of greatest vulnerability in the life cycle of the plant, requiring moderate humidity levels, medium to high light intensity, and adequate but not excessive soil moisture.
Most indoor growers use compact fluorescent or T5 fluorescent lights during this stage as they produce little heat. High-pressure sodium and metal halide lights produce large amounts of radiant heat and increase the rate of transpiration in the plant which can quickly dry out seedlings with their small root systems.
This cannabis plant is being grown in a coco coir medium. It is only making stems and leaves at this point because it is in the vegetative stage.
Duration: 1–2 months indoors. In this stage the plant needs a significant amount of light and nutrients, 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.
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 are then usually culled when they are identified, so that the females will not be pollinated, thus producing parthenocarpic fruits (popularly called «sinsemilla«, meaning «without seed»).
During the vegetative phase, cultivators generally employ an 18- to 24-hour photoperiod because the plants grow more quickly if they receive more light, although a warmer and cooler period are required for optimal health. 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. Energy savings often support using a dark period, as plants undergo late day decline and therefore lighting during the late night hours is less effective.
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 nitrogen and potassium during the vegetative stage, as well as a complete micronutrient fertilizer. The strength of the fertilizer is gradually increased as the plants grow and become more hardy.
Advanced cultivation methods include:
- 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.
- using a water or air-based growth medium (known as hydroponics and aeroponics respectively)
- the use of homemade, organic composted fertilizers
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 (g/W) harvest.
A young male cannabis plant during early flowering stage
Also called the stretch, this takes one day to two weeks. Most plants spend 10–14 days in this period after switching the light cycle to 12 hours of darkness. Plant development increases dramatically, with the plant doubling or more in size. (See reproductive development below.) Production of more branches and nodes occurs during this stage, as the structure for flowering grows. The plant starts to develop bracts/bracteoles where the branches meet the stem (nodes). Pre-flowering indicates the plant is ready to flower.
Flowering and fruition
A flowering female cannabis plant
The flowering phase varies from about 6 to 12 weeks for pure indicas with their shorter flowering time than pure sativas. Mixed indica/sativa strains have an intermediate flowering time. The sex is clearly revealed in the first phase, the actual flowering. Males produce little ball-like flowers clustered together like grapes called panicles. Most plants (except auto flowering strains that flower independently of photoperiod) begin to flower under diminishing light. In nature, cannabis plants sense the forthcoming winter as the Earth revolves about the Sun and daylight reduces in duration (see also season). The next phase consists in the fruition (or fruiting): the females inflorescences that were not pollinated (i.e.: fertilized by male pollen) start to produce infructescences that contain sticky white resin-containing glands (or trichomes) in a final attempt for pollination by windborne male pollen. The trichomes produce resins that contain the largest amounts of THC and CBN, the two main psychoactive substances. Fertilized females continue to produce resinous trichomes but more plant energy is consumed by the production of seeds, which can be half the mass of a fertilized bract; thus, to maximize resin per gram, infertile cultivation is preferred.
The buds of a male cannabis plant
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 use 12 hours of darkness.
Outdoor cannabis cultivation
To generate optimum quantities of THC-containing resin, the plant needs a fertile soil and long hours of daylight. This means THC production for outdoor growth occurs optimally anywhere within 35° of the equator. Typical growing regions include Mexico, Nepal, Northern India, many parts of Africa, Afghanistan, the United States 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.
Indoor cannabis cultivation
Indoor cannabis cultivation
Cannabis can be grown indoors in a soil-like medium under artificial light, adding 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.
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
There are several different plant grow lights available. Currently the best source of light for cannabis remains to be metal halide or ceramic metal halide in the range of 3-4000k. 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).
Flowering room with different light types
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 photosynthetically active range (PAR) of the spectrum.
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 into 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).
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 (18 °F) 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. Power supplies that can be unscrewed from lamp luminaires can be placed outside grow tents to reduce the temperature a bit.
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 their 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 lamps.
Some growers will construct grow cabinets made out of an old refrigerator, cabinet, dresser drawer or similar.
Popularity and extent
Indoor cannabis plant during flowering
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. Power companies inform law enforcement if they see a significant increase 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 C. 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 black market 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.
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:
- Seeds are harvested when fully developed and often after the accompanying buds have begun to deteriorate.
- Hemp grown for fiber is harvested before flowering,
- Cannabis grown for cloning is not allowed to flower at all.
- Cannabis grown for smoking
A typical indicator that a plant is ready to be harvested for smoking, is when most trichomes have turned cloudy and 5% to 15% of the trichomes have turned a reddish brown/amber.
In general, harvesting consists of drying and curing. Curing is an oxidization and polymerization process which takes place in sealed containers of cannabis, over time.
- Dry: Buds placed in a controlled atmosphere for removing moisture content
- Cure: Buds stored in sealed container and left in dark place
Ripeness is defined as the point where THC and other cannabinoid production has reached maximum levels, but before cannabinoids have begun to degrade/breakdown. This is seen under a 30–60x microscope by examining the trichomes on the flowers. When trichomes are undeveloped they are completely clear. They turn white/cloudy which is when trichomes have max levels of cannabinoids. Eventually trichomes start turning amber/purple/red, which is when cannabinoid content has started to degrade. Harvesting before most trichomes have turned white may reduce the overall potency and efficacy time. Harvesting too late (past 15% amber) produces more of a sleepiness effect as the THC degrades to CBN.
Some growers use a brix to measure «sugar» content.
The plants are dried at room temperature in a dark space. It is actually optimal to keep the temperature between 60 and 70 °F (16 and 21 °C) 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 °F (21 °C). 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 should be 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 from which to hang the plant. Roots are removed, and when the stems in the middle of the largest buds can be snapped easily, the plant is considered 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.
Harvested whole cannabis in a drying room at a legal grow facility in Alaska
Cannabis is fully dry for «curing» when the moisture level reaches 55–65% RH. A simple way to check this is by closing the cannabis up in an airtight glass container with a hygrometer. The container is stored for 12 hours at 22 °C (72 °F) and the hygrometer checked. 65% and above readings mean the jar needs to be opened for a few hours and then closed up, to allow more moisture to escape. The jar is again checked after 12 hours and the process repeated until a steady 55% is reached.
Brick weed is a curing and packaging method of cannabis cultivation that consists in drying the bud for a short period, if at all, and pressing it with a hydraulic press, compacting the whole plant (bud, stems and seeds) into a brick, hence the name brick weed. This method is mainly used in the top cannabis producing countries like Mexico and Paraguay where it is largely exported. Brick weed has a low THC level and less potent aroma and taste.
If any of these pests are caught too late, eradication of many destructive species may prove futile unless all infected plants are removed from the space and sterilization methods employed.
Organic and inorganic pest controls
Substances that have been used and considered to induce little or no harm include:
Substances used on cannabis but unknown if harm could occur:
This indoor cannabis plant has not been trained and is growing in the natural Christmas tree shape that is common for untrained cannabis indica.
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. Some cultivators employ plant training techniques to increase yields indoors:
Topping is the removal of 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 nigh 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.
These indoor cannabis plants were trained to grow flat in order to take better advantage of the grow lights and increase yields.
Pinching (also called «FIMing») 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.
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.
These two cannabis plants are being grown in a DWC (deep water culture) hydroponic system. They are in the vegetative stage and are being grown in a 4’x4’x7′ grow tent under a 600W MH (Metal Halide) grow light.
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.
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, and then growing a number plants to find which exhibit the characteristics most desirable. These genetics should typically yield at least 1 gram per watt per month of flower.
Mature mother plants that have been moved to flowering room for harvest
Plant characteristics generally selected for include:
- Overall yield
- Time to fruition
- Resistance to pests
- Geometric traits (uniformity, compactness, flower density, etc.)
- Flavor and/or aroma
- Appeal to end buyer (known as «bag appeal»)
- Psychoactive qualities
- Trichome density and type (stalked or sessile)
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 Cannabis ruderalis with its autoflowering characteristics. The plant produced from an autoflowering seed 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 is needed. Flowering is dependent on the plant’s age, as opposed to time of year or ratio of light and darkness. Autoflowering varieties will bloom from seed in 12/12, 18/6, 20/4 or even 24/0 lighting, referring to light/dark time respectively.
The first autoflowering cannabis seed on the market was the Lowryder #1. This was a hybrid between a cannabis ruderalis called 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.
After many years of autoflower inbreeding seed makers have now come up with autoflowering strains that can produce yields close to the regular strains and still are flowering independent from the light cycle. The first autoflowering strains came from breeder STICH but now almost all major seed companies have their strains of super autoflowers that can grow up to 2 meters and produce yields up to 900 g/m2 of growth.
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 of the psychotropic material. It is possible to use a combination of cloning and «shocking» of 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 the tendency of hermaphroditism. Others believe that this method utilizing auto-hermaphroditic traits is offset by grower observations that the tendency to auto-switch sex is no greater in plants grown from seeds made this way, than occurs naturally.
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.
Caution should be exercised, as one does not always attain a beneficial cross with hybridizing.
Vegetative propagation (cloning)
Young cloned plants in a vegitating room with a hydropnic system
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».
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.
- 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.
- The cut end is brought to contact with rooting hormone, according to instructions, to promote root growth and inhibit fungal infection.
- 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 (77 °F)) and direct light is avoided so that the cutting does not dry out. The production from the slower photosynthesis is put into root production.
- 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.
«Blueberry» cannabis cuttings waiting to be trimmed and re-cut
Trimmed with stem re-cut at 45 degree angle below a node
New clones under improvised humidity domes
Fan leaves in a trash receptacle
Environmental impact of cannabis cultivation includes all the environmental issues which occur as a result of cannabis cultivation.
- Miriello, Ross (2016). Cannabis Botany and Marijuana Horticulture Naturally Medicinal. Maison Hydroponique. ISBN 978-1548501594.
- Cervantes, Jorge (2001). Indoor Marijuana Horticulture. Van Patten Publishing. ISBN 1-878823-29-9.
- Cervantes, Jorge (2006). Marijuana Horticulture: The Indoor/outdoor Medical Grower’s Bible. Van Patten Publishing. ISBN 1-878823-23-X.
- Clarke, Robert Connell (1981). Marijuana Botany. Berkeley: Ronin Publishing. ISBN 0-914171-78-X.
- Green, Greg (2003). The Cannabis Grow Bible. San Francisco: Green Candy Press. ISBN 1-931160-17-1.
- Herer, Jack (1998). The Emperor Wears No Clothes. Ah Ha Publishing. ISBN 1-878125-02-8.
- Starks, Michael (1990). Marijuana Chemistry: Genetics, Processing & Potency. Ronin Publishing. ISBN 0-914171-39-9.
Music and reception
- American rock band Person L covered the song for the Fearless Records compilation Punk Goes Crunk in 2008.
- Italian soul singer-songwriter Zucchero Fornaciari imitated the style and arrangement of the song, without directly covering it, on «Un kilo», a song from his 2006 album Fly. As «Un kilo» is not a full cover, it was credited only to Fornaciari.
- «The Seed (2.0)» music video at YouTube