Cannabis Plant Science

Botany of Cannabis

Cannabis is a flowering short-day (Begins to flower once days become shorter) plant.  It is a dioecious plant, which means it can contain both male and female reproductive parts. However, almost all cannabis grown commercially are monoecious where growers focus on females which produce pistils (the female reproductive organ) and highly valuable flowers or “bud.” Males produce sacs full of pollen and stamens (the male reproduce organ) and are generally just used for breeding purposes when breeders want to create new cultivars or genetics.

The main components when discussing the botany of cannabis are three separate compounds which are found in various amounts in the flower. The first is cannabinoids, which are chemicals that are found in cannabis as well as throughout the human body. When they interact, they will produce many different physiological effects that give therapeutic solutions to many human ailments. THC (tetrahydrocannabinol) is the most recognized cannabinoid and the primary psychoactive component of cannabis. Secondly, cannabis plants produce trichomes which are resin filled glands produced by the plant. Trichomes contain the highest concentration of cannabinoids as well as various levels of terpenes. Trichome production is essential to growing a plant with great medicinal benefits. Finally, cannabis plants will produce terpenes, which give all cannabis plants distinct aromas and flavors. Terpenes have been researched and proven that they can enhance or alter the physiological effects of cannabis when combined with cannabinoids. There are over 100 different terpenes and each strain differs in the amount of terpenes they produce. Combining these three components has been proven to give the best medicinal benefits to patients.

Cannabis is taxonomically listed under the family Cannabaceae, genus Cannabis and currently divided into three separate species Cannabis Sativa, Cannabis Indica, and Cannabis Ruderalis. Each of these species differ from each other in aspects of physical appearance, physiological effects, and growth cycles.

Cannabis Sativa are taller than the other species ranging anywhere from 10-20ft in height, its tall lanky structure makes it great for fiber production when producing construction materials. Their leaves are narrow and are sparsely located throughout the plant canopy. They require longer growing period to reach full maturity compared to the other species. Cannabis Sativa produces flower that when inhaled or ingested will cause more of a “Mind High” often accompanied by large amounts of energy, clear thoughts, and anxiety-reducing effects. Sativa is recommended to be used during the day.

Cannabis Indica plants are smaller than cannabis sativa and will range in height from 5-10ft depending on maturity. Their stems and leaves are much thicker than sativa and are densely packed throughout the canopy giving the plant a stocky bushy appearance. Their growth cycles are generally shorter than sativa. Cannabis Indica produces flower that when inhaled or ingested will cause more of a “Body High.” Indica is great for inducing relaxation, appetite stimulation, sleep aid, and pain relief. It is recommended to use Indica during the evenings.

Cannabis Ruderalis is defined as “ruderal”, a ruderal plant will grow in any environment or condition . Ruderalis is the smallest of all cannabis species ranging anywhere from 1-3 feet in height. They have very thick sturdy stems and sparse but wide leaves (Not as wide as Indica). They are generally light green in color, which is different compared to the dark green appearance of sativa and indica. The factor that completely distinguishing ruderalis as a different species is that they are an “autoflower” cultivar. This means they will begin to flower and produce “buds” when they reach physical maturity and not when the light cycles begin to change like photoperiodic plants do. It will generally take anywhere from 20-40 days for a ruderalis species to begin to flower. These plants are primarily used for breeding purposes when breeders cross either sativas or indicas with ruderalis to make autoflower strains with higher cannabinoid content.

The cannabis plants growth cycle can be broken down into four different stages. Before we get to enjoy the desired cannabis flowers filled with various cannabinoids and terpenes that we all admire and consume, cannabis life starts in the form of a seed. We recognize this first stage as the germination stage. During this stage the temperature should be between 70-85 degrees fahrenheit with a relative humidity of around 65-80%, and under a 24 hour light cycle. It is here where we can use different methods to break the dormancy of the seed that will then allow it to germinate such as the paper towel method that we all learned in basic biology class, or simply just sowing/planting the seed directly into your growing media of choice. Although strain dependent, the germination stage can happen over a 24 hour period or it can take up to 10+ days to occur. It is here where the seed will imbibe water which will activate metabolic processes within the seed that will trigger the emergence of the first root, also known as the radicle. Soon after the radicle develops and starts to drive down into the media in search of water and nutrients, the new emerging stem(hypocotyl) starts to drive upwards through your medium in search of light. It is here where we start to see the first leaves called cotyledons emerge from the ground, soon after the cotyledons are present we will see the plant start to develop its first true serrated leaves that we all recognize and that are indicative of the cannabis plant. Once these first true leaves are present they will begin to photosynthesize and we will officially be moved onto the seedling stage.

We can expect the seedling stage to last anywhere from 2-3 weeks depending on the strain and the environment in which the seedling is in. Speaking of environment, in this stage we like to keep a 18-20 hour light cycle so the plant can have time to rest and focus on respiration and energy production, however due to how fragile the cannabis plant is in this stage we like to lower and maintain a temperature of around 68-77 degrees fahrenheit with a relative humidity still around 65-80%. High humidity will help allow the seedling to absorb water through tiny pores on the leafs surface called stomata so that it can focus stored energy on establishing a healthy root system. As the seedling further develops we will see a morphology change from the original single serrated leaf, to where more leaf blades will start to be produced and the plants leaves will begin to take on its iconic and traditional 5-7 leaf blade shape/structure. Once the seedling is producing multiple leaves like this (also known as fan leaves) we can then definitely say it’s moved on to the vegetative stage.

During the start of the vegetative stage is when you would transplant your mature cannabis seedling/early veg plant into a larger pot or its final home. It is after this where we really start to see the plant grow and rapidly develop new biomass in terms of root and shoot growth. This type of growth should be your main focus as the grower at this point. The ideal environment for this stage of growth is with your temperature being maintained at around 65-87 degrees fahrenheit with a relative humidity between 60-80%. Higher temperatures will  correspond to having a higher relative humidity to maintain vapor-pressure deficit so that nutrient and water uptake is operating at an optimal capacity which will result in having more robust plants. The vegetative stage usually lasts anywhere from 2-16 weeks and can last indefinitely as long as 18 hours of lights being on is maintained. Once the plants photoperiod is changed to a 12/12 or twelve hour on and twelve hour off light cycle, will the plants then be able to enter their final stage of growth being the flowering stage.

Although not necessarily advisable, this is your last chance to transplant your cannabis plant into its final home if not done so already and should be flipped to a 12/12 light cycle. We are now into the final stage of your cannabis plants life where it will reach full maturity, this phase is known as the flowering stage and can last anywhere from 6-12 weeks. The ideal environment for your plants at this time will be with a temperature between 65-80 degrees fahrenheit with a relative humidity of 50-70%. It is recommended to keep your temperature and relative humidity on the lower end of the vapor-pressure deficit chart to not only combat a number of potential risks such as bud rot, but to also slow down terpene degradation. Your main goal as a grower at this point is to focus on the production of buds/flowers. After a few weeks into the flowering stage your cannabis plants will start to produce their sexual reproductive organisms and show signs of sex in the form of pisitls(for females) and stamens(for males). It is in this stage where you want to remove and cull out your males to decrease the chance of them pollinating your females. This is due to the fact that the cannabis flowers we crave for consumption are produced from the female plants and are not as desired if seeded. These desired flowers we are after are covered in trichomes which are then filled with various different types of terpenes and cannabinoids in which we can attribute to the appealing effects and medicinal benefits we receive from the plant. Once your buds are developed and reach maturity your job as a grower will then shift to focus on the maturation rate of your trichomes by looking at them through a 60x jewelers loupe or 100x magnification scope. Based on the maturity of your trichomes they can either be clear,cloudy,or amber and the ratio of said three will be what manipulates the effects and tells you when to harvest your plants. Many growers recommend a 20% amber ratio to be seen in the trichomes when looking through the scope, after this is achieved the plants are ready to move onto the drying and curing process.

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