We take you through the various life stages of a cannabis plant from seed to harvest and post-harvest processing steps.
by Lim Guan Yu
The grass is greener for the cannabis market. Medical cannabis have been drawing attention in recent years. Over the past five years, countries like Australia, America, Uruguay and most recently, Canada and Thailand, have legalised the use of medical cannabis, some even recreational cannabis. Just last year, the U.S. Food and Drug Administration (FDA) approved the first-ever cannabis-based drug Epidiolex, which uses a marijuana derivative, to treat seizures caused by a rare form of epilepsy called Lennox-Gastaut Syndrome (LGS) and a genetic brain dysfunction called Dravet syndrome.
The increased demand for medical and recreational cannabis have seen cannabis producers ramping up production, and even turned some people to grow their own.
If you wondered how some people grow their own cannabis in countries that have already legalised, we’ll show you the life cycle of the plant from seed, germination, seedling, vegetation, flowering, to the final harvest, which moves on to post-harvest: drying, processing, extraction and packaging.
Cannabis, also known by its many names such as weed, lives up to its name. It grows like a weed. Here is the growth process of the cannabis plant.
For commercial growers, the seeding stage is usually skipped because the seeds take a long time to germinate and are prone to genetic variation, which then affects the quality of the cannabis product. So, new plants are grown from the cuttings of established ones, producing genetically identical plants with the desired characteristics.
For DIY growers, the male and female seed must first be differentiated. Male plants only produce pollen to pollinate the female plants, but the female plants produce cannabinoid-filled buds and flowers, which are sought after. If the male and female plants are grown together, the female plant will be pollinated and start producing seeds, resulting in no buds being formed.
When it comes to growing cannabis, soil nutrition, temperature, lighting, and ventilation can make all the difference. Whether cannabis seed or cuttings, they prefer a moist, low light, and high humidity environmdent.
For cuttings, they are first placed in a small pot. After about two weeks, the roots will start to sprout, and the seedling will be transplanted to a larger pot. A single plant can grow up to five feet tall (1.5m) with a wingspan up to three feet (0.9m).
For seeds, they are first moistened with water and left in a warm dark place for 24 hours until the seed sprouts its taproot. The seeds are then transferred into a pot of healthy soil. The taproot will attach itself to the soil and start soaking up the nutrients.
During this stage, the stems, from cuttings or seeds, will continue to grow upwards. The first two leaves produced are the embryonic leaves, which are smooth-looking. The next pair of leaves to grow after the embryonic leaves are the round-pointed marijuana leaves, and the seedling will grow up to eight leaves in this stage. This stage can last between one to three weeks depending on factors like soil type, amount of water, airflow, humidity and amount of light.
It is important to ensure good ventilation and air exchange. A good air circulation can boost carbon dioxide replenishment, aids in water and nutrient absorption to strengthen the stems. It is best to avoid direct ventilation by pointing fans directly at plants, as this can dehydrate the seedlings and result in wind burn, which makes the leaves curl and droop.
In the vegetative stage, the plant’s stem will grow thicker and taller, developing new nodes, which will further produce more leaves and branches. This stage takes the plant from an eight-inch baby plant to three-foot-tall, in the span of three to six weeks.
The plant’s growth is largely depending on the amount of light it receives. Vegetative plants will need long hours of natural sunlight (up to 15 hours) or 18 hours of fluorescent/LED light daily.
Soil nutrition is also important as vegetative plants need a large amount of potassium and growth-fostering nitrogen (e.g. liquid fish, seaweed) with a lesser amount of phosphorus.
To get the plant to the flowering stage, the amount of light it receives will be reduced to 12 hours, prompting it to produce flowers (also called buds). The time needed for a plant to flower depends on the strain, taking anywhere from one to five months.
At this stage, the plant will need more potassium and phosphorus-based nutrients to produce buds. Nitrogen-based nutrients should be reduced as it prevents the buds from reaching the full growth potential and also create an unpleasant chemical flavour and aroma.
To maintain optimal bud health, it is important to balance humidity levels. Low humidity is recipe for spider mites and wilted plants, while high humidity can accelerate bud rot.
In the last three weeks before harvest, humidity should be brought as low as possible. The dryness is said to prompt trichome production, which contain cannabinoids, the psychoactive/medicinal ingredient in cannabis, helping to relief symptoms like pain, nausea, inflammation, almost others.
Trichomes are hair-like glands coating the flower or bud. They also contain terpenes, the fragrant oils which produce a unique taste and smell.
It is time to harvest when the trichome heads turn from clear to milky and opaque to amber. More amber trichome heads are likely to indicate a higher cannabidiol (CBD) to tetrahydrocannabinol (THC) cannabinoid profile.
The plants are then cut into smaller branches, the buds are separated from the stems and leaves before they undergo the drying process.
In the drying process, the buds are dried on the racks for two weeks, before they are stored in loosely closed bins before being processed. Keeping them in the closed bins help to retain the terpenes and control humidity.
After drying is completed, the buds are graded by size. Larger buds are used for flower sales, while smaller buds are used for making cannabis oil. To ensure consumer safety, the buds will undergo quality testing.
For cannabis oil production, the buds are put through an extraction process which first involves grinding. The grinded buds are then baked, the heat helps to activate the psychoactive/medicinal ingredients. Using heated and pressurised carbon dioxide, the cannabinoids are separated from the bud in an extraction machine. This results in a liquid containing the cannabinoids, which is mixed with a carrier oil, such as a type of coconut oil known as medium chain triglycerides (MCT oil). The oil is then bottled or encapsulated in preparation for sale.
The finished products will be packaged and labelled as per the country’s specific guidelines. Cannabis products must be properly labelled to ensure consumers are informed about their purchase and to prevent unintended use. Labelling usually include the product description, universal symbol that identifies cannabis-containing products, weight/volume, THC or CBD per package/serving, manufacturer’s name and contact, date of manufacture, expiration date, batch number, list of ingredients, instructions for medical use/consumption, and a warning statement for use of cannabis products.