Cannabis Cultivation: An Introduction to Growing Marijuana

Our relationship with cannabis arguably begins and ends with cultivation. All forms of cannabis that we consume derive from a cultivated plant. The value of the cannabis plant, medicinal or otherwise, is largely dependent on what we do with it — how and when we grow it, how we refine it for our own consumption, and even what words we use to describe it.

Cannabis is a dioecious plant, meaning it can be categorically divided into male and female plants. Male plants produce the pollen necessary for a female plant to produce seeds, while the female plant is the only plant to naturally produce the major cannabinoids,  namely cannabidiolic acid (CBDA) and tetrahydrocannabinolic acid (THCA). Cannabis also produces several other valuable compounds, such as terpenes and flavonoids, that potentially work synergistically with marijuana’s cannabinoids to enhance desired and therapeutic effects.

While still highly debated, most countries only recognize one cannabis species, Cannabis sativa, but some recognize up to three species — C. sativa, C. indica, and C. ruderalis — based on geographic origin, genetics, and morphology. The central difference between today’s Indica and Sativa plants is in their observable traits during the cultivation cycle.

Indica plants tend to grow short with thick stems and broad, deep-green leaves. They also have short flowering cycles, and grow sufficiently in cold, short-season climates. Sativa plants have longer flowering cycles, fare better in warm climates with long seasons, and usually grow taller with relatively light-green, and narrow leaves.

Knowing the morphological, or physical, form difference between Indica and Sativa plants is more useful to growers and cultivators than virtually anyone else in the cannabis space, despite the terms’ common use in the consumer marketplace.

Cannabis Flower Keif and Oil

Every part of the cannabis plant is usable. Historically, cannabis has been bred by humans for three distinct purposes:

  1. Fiber – harvesting cannabis stalks, typically from hemp varieties.  
  2. Seeds – harvesting seeds from a female hemp plant for its rich oil and protein content.
  3. Drug-type cultivars – harvesting cultivated varieties for their psychoactive and therapeutic cannabinoids.

From seed to harvest, the cannabis plant’s growth cycle can last anywhere from 10 to 26 weeks. The cycle has three main stages: germination, vegetation, and flowering. Like most plants, cannabis requires light, air, nutrients, and a medium to house its roots. The amount and duration of light the plant is exposed to dictates which growth stage it will be in.

Local Cannabis Cultivation Laws and Regulations

In most countries and local jurisdictions where cannabis is legal — medically or recreationally — some sort of home growing is typically allowed, but growing laws vary significantly from country to country and even city to city. If you’re a prospective and current home grower, you should know the laws and regulations of your jurisdiction before you start growing cannabis.

Cannabis Plant Sex and Anatomy

Male and female cannabis plants share a common basic anatomy of roots, stems, and leaves. Both plant sexes produce trichomes, the glandular appendages on the surface of the flower that produce and hold the plant’s cannabinoids and terpenes, however, the female plant produces far more trichomes than the male plant. Beyond these basics, cannabis anatomy varies significantly between male and female plants.

Over the course of our shared history with cannabis, authors, scientists, growers, and industry insiders have used competing terms to describe the same reproductive plant anatomy. Due to an extensive period of prohibition, botanical terms have been frequently misused or replaced entirely. What’s more, popular colloquial terms have become interchangeable despite having different meanings.

So, let’s alleviate some of the confusion and map out the anatomy of both plant sexes by first identifying botanical terms, then clearing up some of the common colloquialisms we’ve inherited.  

Anatomy of the Female Plant

The female cannabis plant is a pistillate, meaning it has pistils and stigmas. You may have heard female cannabis plants referred to as “sinsemilla,” translated from Spanish as “without seeds.” Sensemilla refers to all non-pollinated female plants. Sensemilla plants are ideal for marijuana growers because they offer the highest potential yield of cannabinoids. Pollinated female flowers, or female flowers with seeds, produce a less smokable product than flowers from seedless marijuana.

The reproductive anatomy of the female plant includes:

  • Colas: The flowers produced by the female plant. Colas are covered with cannabinoid- and terpene-rich trichomes and commonly called buds or nugs. A cannabis bud is not to be confused with the botanical definition of the word bud: a newly emerging plant.
  • Bract: A small, scale-like leaf structure that encapsulates and protects the seed. Bracts are often referred to as calyxes, though this term is botanically incorrect. The female cannabis plant does, however, have calyx cells within the delicate layer of tissue between the seed and the bracts that encapsulate it.
  • Stigmas: The reproductive parts of the cannabis plant, which catches pollen from the male plant. Stigmas are commonly and incorrectly referred to as pistils.
  • Pistil: The reproductive parts of the female cannabis flower that are activated if pollen is captured by the stigmas.
  • Sugar Leaves: The small leaves that hold cannabis buds together. They are called sugar leaves due to the high concentration of trichomes that have a sugarlike appearance.

Anatomy of the Male Plant

The male cannabis plant is a staminate, meaning it has stamen or pollen-producing reproductive organs. Male plants are cultivated for fiber and for breeding new varieties. During their flowering phase, male cannabis plants release pollen, which will prompt a female plant to start producing seeds. This practice diverts energy from flower production and reduces the overall yield. To maximize your flower yield and prevent seed production, keep male and female plants as far away from one another as possible.

The male cannabis plant is capable of producing cannabinoids, but its trichomes are sparsely dispersed across its surface. Males do not produce nearly as many trichomes as a female.

The reproductive anatomy of the male plant includes:

  • Stamen: The organ of the male plant that produces pollen and releases it into the wind, where it may be carried to the stigma of a female plant for pollination.
  • Anther: The sacks that produce and hold pollen within the stamen. Anthers hang by a small filament. Together, the anther and the filament make up a stamen.
  • Pollen: Microscopic grains produced and contained in the anther that fertilize the female plant when released.

Hermaphrodite

A hermaphrodite is a rare monecious plant, meaning it develops both male and female sex organs. The term monecious stems from the root “mono,” meaning “one.” While there are multiple reasons that a plant may exhibit both signs, hermaphrodites are primarily formed if a female plant is exposed to extreme conditions during key stages of growth, such as insufficient light or harsh environmental conditions. Signs of a hermaphrodite typically show late into flowering.   

In a final attempt to continue their seed line, a sensemilla crop will occasionally produce a few hermaphrodites. While the pollen of these hermaphrodites is frequently unviable, marijuana growers should remove hermaphrodites when they occur to eliminate the risk of pollination. Hermaphrodites will also produce a lower overall flower yield as the plant is forced to divert energy into the production of seeds that would have otherwise been used for the production of trichome-rich flowers.      

The Three Main Growing Environments for Cannabis

Outdoor

Growing cannabis outdoors exposes a crop to the elements, offering natural light and significantly reducing costs for growers. With no artificial lights or fans required, electricity may only be required for irrigation.

While exposure to a natural environment is generally good for plants, exposure to harsh environmental conditions may present hindrances to an outdoor crop. Rain, insects, invasive plants such as thistle, animals, and extreme weather conditions are all potential crop killers. Outdoor cultivation also limits cultivators’ control over environmental crossover from neighboring fields. In short, your fellow farmer’s pesticides could end up being your pesticides if they’re not expertly applied.

Outdoor cannabis cultivation relies on the available sunlight during the changing seasons, during which the plant is exposed to the full spectrum of light available in nature at that time of year. Outdoor cultivators experience a longer growth cycle and typically only harvest once a year.

Greenhouse

Growing cannabis in a greenhouse offers the free sunlight of an outdoor grow, but with far greater environmental control. Greenhouses allow growers to control natural light with a blackout shade or similar roof covering system. Greenhouses also offer the option to add electrical lighting to supplement sunlight on cloudy days with an added layer of protection from animals, pests, and extreme environmental changes.

One of the downsides to greenhouse cultivation is the upfront cost required to have such a structure. Greenhouses range from temporary structures made of plastic and PVC pipe to permanent structures that allow growers to control every environmental aspect and utilize advanced cultivation methods, including light deprivation.

Another risk in greenhouses is that pests can spread inside the enclosed environment at a faster rate. Protection against environmental crossover is also limited depending on the type of greenhouse structure.

Indoor

Indoor growing is usually performed in a warehouse setting, which requires artificial lighting and use of air conditioning and dehumidification systems. The intention of an indoor grow is to mimic the elements of the outdoors that facilitate plant growth while maintaining full control over every environmental parameter. The major downside of indoor growing is the high upfront and recurring costs that come with the building structure, equipment, water, electricity, and other utilities.

Cannabis Propagation Techniques

Propagation encompasses the entire growth cycle from seed to harvest. Cannabis can be grown either from seeds or a cutting from another plant.

Seed

Cannabis seeds, formed when pollen fertilizes the female plant, are ready to plant and grow as soon as they successfully germinate, or once the root has broken through the seed. While you can plant your seeds directly into the ground, it’s recommended to germinate them in a moist paper towel before planting. Home cultivators often start with feminized seeds to ensure that the adult plant is a flowering female.

Propagation through seeds is commonly known as sexual propogation, and is an often preferred method for outdoor cannabis cultivation because it makes for a more durable plant. Not only do sexually propagated crops have a greater yield potential than clones, they’re also more resistant to pests, illness, and diseases.

The most frequently cited disadvantage of growing plants from seeds is inconsistency. Plants propagated by seeds do not maintain the exact phenotype or observable physical characteristics and chemical traits of the parent plant. This causes variances and inconsistencies in the cannabinoids and terpenes that growers and consumers usually find undesirable.

While most growers want uniform plants, occasionally growers will grow a large amount of plants from seeds so they can choose plants that produce unique physical and aromatic characteristics. This practice is commonly referred to as pheno hunting and is practiced by most nurseries.

Clones

Asexual propagation, also known as cloning, is the replication of a single parent plant outside the means of sexual reproduction. Cannabis clones typically start with a cutting of a stable mother plant, which is likely to grow into a genetically similar plant under the right growth conditions. A clone’s central purpose is to reproduce and preserve the genetic identity of a cannabis plant. When grown under the exact same environmental conditions as the mother plant, a clone is infinitely more likely, than a plant grown from seed, to exhibit the mother plants physical traits, as well as its cannabinoid and terpene profile. It should also mirror the mother’s ability to take in nutrients and resist pests or fungi.

Because they’re not exposed to the genetics of multiple plants — instead receiving the same genetic code as the mother plant — clones stand a far better chance of preserving the desired characteristics of a parent plant. Plants grown from clones also allow growers to determine which environmental conditions will maintain those ideal genetics, and determine optimal feeding schedules, flowering times, and nutrient recipes.

Lack of genetic diversity is a good thing for growers, but it can also have catastrophic consequences. If plants are exposed to adverse environmental conditions for which they have no genetic defense, an entire crop can be wiped out.

Selecting a Cannabis Growing Medium

Whether a plant is grown from clone or seed, both need a medium to serve as the base for a healthful life. A growing medium is the material in which plants are set during the growth cycle. Whether you use hydroponics, aeroponics, or traditional soil cultivation, your selected growing medium needs to provide the plants roots with air, water, and nutrients.

Soil

Soil is the most common medium for growing cannabis. Healthful soil is an exceptionally stable growing medium, allowing for sufficient moisture retention that provides the grower ample time between watering sessions. Soil is readily available and relatively easy to work with, which makes it an effective growing medium for the widest spectrum of growers — from prospective home growers to bona fide experts. Soil can be used for both indoor and outdoor growing.

Hydroponics

wmlearn-hydroponics

Hydroponic cultivation is the preferred medium for indoor cultivators, feeding plants through a nutrient-rich liquid solution. Perlite, vermiculite, coco coir, and hydroton balls are all commonly used hydroponic media, which allow for optimal uptake of nutrients and reduced water usage compared with soil. Hydroponic methods are also frequently used in greenhouse settings, but not commonly used for outdoor growing.

The major downside of hydroponics is the rigorous attention to detail the practice requires. Hydroponic media are much more sensitive to severe temperatures. Too much heat, in particular, can be very damaging as it invites bacteria and disease. Meanwhile, the water’s pH and nutrient levels must be consistently monitored to ensure the plant is getting what it needs to grow strong.

Aeroponics

Aeroponics function similarly to hydroponics, but rather than maintaining the plant’s roots submerged in water, an aeroponic system suspends the plant roots in an environment of mist and air where they absorb water, nutrients, and oxygen. An aeroponic system arguably has the most potential for maximum yield, but it’s also much more temperamental than other systems. Both environmental and growth control factors must receive careful, constant attention for an aeroponic system to be effective.

Germinating Seeds or Rooting Cannabis Clones

The germination phase takes place from the moment a seed’s embryo is exposed to water until the seed has sprouted its plumule, or initial taproot. Germination only occurs when plants are grown from a seed, and usually takes between 12 hours and three weeks, depending on the vitality of the seed, age of the seed, and germination techniques selected by the grower.

The simplest way to germinate a cannabis seed is by placing it about 3 millimeters deep in moist soil. Germination soils are also an option, designed with micronutrient blends that facilitate healthy sprouting. Many growers prefer towel germination, in which seeds are placed between two damp paper towels, then immediately transferred into a growing medium once the taproot is exposed.

If growing from a clone, the rooting phase is the time in which the plant develops its taproot. During this time, the young cutting is exposed to 24 hours of light in an environment with a high humidity. This can take anywhere from 3 to 14 days.

Cannabis Vegetation

The vegetative phase is when the plant grows its roots, stalks, and large fan leaves that will ultimately be used to convert the sunlight into the sugars that it needs to produce the plants flowers or seeds. The light cycle is typically reduced to 18 hours of light, as it requires a minimum of 16 hours of light to maintain the plant from beginning to end. During cannabis vegetation, cultivators can train their plants or manipulate their growth patterns for a multitude of reasons. Indoor growers may want to train their plants to stay short by growing horizontally, while outdoor growers may want to force their plant to develop multiple flower growth sites at the same level.

Training Techniques

There are several training techniques indoor growers deploy to get an optimal yield out of their plants within limited space and lighting conditions. All of them involve manipulating the shape and growth of the plant, usually by bending the stem in some fashion or another.

Sea of Green (SOG)

The Sea of Green (SOG) technique involves growing several small plants instead of a few large ones with the intention of maximizing space and cultivating single colas. With the proper setup, a SOG grow promotes the shortest vegetative phase to produce short and dense colas.

Low Stress Training (LST)

Low Stress Training (LST), like most training methods, involves bending and tying down stems for maximum yield and light exposure within a finite space. The “low stress” element of LST refers to manipulating stem growth in favor of bending to prevent the stress that results from breakage or cutting.

Super Cropping

You might think of super cropping as the opposite of LST in that it features strategically executed “high stress,” rather than sustained forms of minimal stress. This method uses targeted stress to encourage cannabis plants to produce the cannabinoids and terpenes they develop for protection. 

Strategically planned and executed stress on the plant is intended to initiate a defensive reaction, thereby increasing the plant’s cannabinoid and terpene production. This type of sustained stress is usually achieved by pinching targeted areas of the stems and tying them down. When growers accidentally apply too much stress, they typically apply duct tape to help the plant heal.

Screen of Green (SCROG)

The Screen of Green (SCROG) method uses LST or Super Cropping to inhibit vertical growth of the cannabis plant by encouraging horizontal growth. This is done by forcing the plants to grow through a suspended horizontal screen. As the crop stems spread laterally across the screen, colas form in otherwise dormant areas of the stem. This technique is used where local laws limit the amount of plants that can be cultivated at one given point, allowing growers to make use of a larger amount of area.

Lollipopping

Lollipopping is removing growth from the lower portion of the plant to divert energy to the higher branches that produce colas, resulting in a “lollipop”-shaped plant. This technique is especially handy for indoor setups that offer minimal light to lower branches and often used on SCROG grows.

Topping and Fimming (FIM)

Topping consists of clipping the growing tip of a plant’s main stem at a 45 degree angle that causes two colas to form instead of one. This method is used to prevent the plant from growing like a Christmas tree by stopping the vertical growth of the main stalk and allowing the lower growth tips an opportunity to catch up. Growers can also “top” a plant multiple times to turn two growth tips into four, and so on.

The FIM method, or fimming, is an offshoot of topping, and derived from topping a plant imprecisely (hence the name FIM, which stands for “F**k, I missed”). Rather than cut the whole tip of a cannabis plant at a 45 degree angle, fimming involves pinching off most of the cannabis tip with the goal of growing four colas immediately in the place of one.

Removing Fan Leaves

Removing fan leaves from the plant can be considered a training technique that aims to divert the plants energy into producing larger colas by limiting the amount of foliage that the plant needs to maintain and increasing the amount of directlight to any growth sites below the canopy. It also helps reduce the likelihood of a pest or mildew infestation. However, fan leaves do take in light and provide energy for the plant, so growers should use caution when removing them.

The Cannabis Flowering Phase

The flowering phase is when the female plant produces trichome-covered colas and when the male plant produces and releases its pollen. Cannabis plants flower naturally during the 12/12 photoperiod when the plant receives 12 hours of light and 12 hours of darkness. In nature, daylight hours are optimal for cannabis plant flowering from July to November in the Northern Hemisphere. On the autumnal equinox in September, the sun is in the sky for 12 hours of the day, with daylight hours slowly reducing until and through the winter.  The opposite is true in the Southern Hemisphere.

Indoors or in a light-controlled greenhouse, introducing an artificial 12/12 light cycle will force a cannabis plant to flower.

When Is Cannabis Ready for Harvest?

A female plant is generally ready to harvest when the glands on the top of the capillary stalked trichomes turn from clear to a milky white color. Some cultivators are also able to use the color of the pistils to time their harvest. Pistils tend to change from either white to orange or red to brown. Growers should also be aware of the typical flowering times of the cultivars they’re growing.

Harvesting Your Cannabis

Once the cannabis plant is ready for harvest, its precious and delicate trichomes are in one of their most vulnerable states. Overexposure to oxygen, light, and heat may degrade cannabinoids and terpenes, or activate them prematurely. Trichomes become more fragile and therefore more susceptible to breaking off the plant if mishandled under extreme conditions. When harvesting cannabis plants, growers should implement methods of drying, trimming, and curing that reduce the amount of agitation of the plant in order to limit any damage to the trichome glands.

Drying

When your cannabis is ready to harvest, cut the whole plant at the base or cut the plant into large  branches. Hang your plant or cuttings upside down on a clothesline in an environment that is not overly dry or humid. At this point, some growers begin manicuring their plants by cutting off all remaining fan leaves and some of the sugar leaves. Plants should be left hanging upside down  to dry until the stems slightly snap when bent.

Avoid losing trichomes by not letting your branches hit any surface while hang-drying. Contact with the surface can damage the trichomes and could cause them to break off the plant. Depending on environmental conditions, the initial drying process usually takes three to seven days.

The trichome gland will experience a few changes during the drying process. The most noticable is a loss of the extremely pungent smell. This is due to a loss of the most temperature sensitive terpenes, or hydrocarbon compounds that produce each cultivar’s unique aroma. Studies have found that upwards of 30% of monoterpenes, or terpenes with two isoprene units — as opposed to the three isoprene units of sesquiterpenes, four isoprene units of diterpenes, and so on — produced during the flowering phase are lost in the drying process.  Additionally, when cannabis is dried, terpene compounds are oxidized, and the terpene technically becomes a terpenoid.

Trimming

Once the initial drying is complete, it’s time to finish trimming and manicuring your bud. Cannabis is typically trimmed to remove the excess sugar leaves that, while consumable, have a smaller concentration of trichomes than the flower and can be harsh when smoked.

Begin trimming by holding your colas by a stem and gently cutting away any sugar leaves and stems that surround the buds. This is a very delicate process that requires attention to detail. Ideally, this is done over a screen to collect and trichomes that may break off the plant. Take extreme care when handling your bud. Every moment of contact can result in trichome loss or damage. Whenever possible, hold your plants and branches by the end of the stem.

Wet Trim vs. Dry Trim

While most cultivators trim their cannabis after drying, some prefer to trim while the plant is still wet. When cannabis is trimmed immediately after harvesting, the leaves are still full of chlorophyll, which may lead to a persistent grass-like aroma. Trimming the plant once it has lost most of its moisture is the more traditional approach.

Curing

Curing can be considered the final drying stage, allowing bacteria on the surface of the buds to break down any residual chlorophyll and ensuring the colas are neither too moist nor too dry.

This should be a gradual process as bud that is too dry will degrade more easily during transportation and packaging, lose potency, and become unnecessarily harsh to smoke. On the other hand, bud that is too wet may grow mold. Preserving fragrance and flavor is a key concern for cannabis cultivators while curing. Overexposure to light, oxygen, and high temperatures can break down cannabinoids and terpenes, and ultimately reduce potency. Striking a delicate balance between dry and moist is the key indicator of a finely cured bud.  

Growers should never rush through curing. The process often requires significant trial and error. One to two months is generally a sufficient length of time for curing, though preference and available time to cure may differ among growers. It’s important to keep the environment around your plants cool during the curing phase.

This curing process can be performed by placing your trim buds in a glass jar or rubbermaid tote for 4-8 weeks. During the first week or two, the containers should be opened daily to allow some fresh oxygen to replace the air in the container. This process is called burping and is repeated until the buds have the optimal moisture content. In the last two weeks of curing the containers are opened every 2-3 days.

Cannabis Storage Tips

Glass jars are the ideal option for short-term storage. Ideally, cannabis jars should be opaque and airtight for ample preservation of cannabinoids and terpenes. For long-term storage, growers should vacuum seal their final product whenever possible.

Cannabis cultivation is a dedicated practice for home growers and professional cultivators alike. To master growing marijuana takes a lot of patience, trial and error, but with time — and a few great suggestions from seasoned growers — you’ll be able to give your plants a healthy life from seed to harvest.