In this post, we will cover the different stages of cannabis cultivation. Starting with pre-harvest to post-harvest, this article is a great primer!
Pre-Harvest is the First Stage of Cannabis Cultivation
Environmental signals such as moisture and temperature signal a hormonal change inside of the plant seed that breaks dormancy. Root radicles break through the seed coat (testa) in search of water, oxygen, and nutrients, and structure. Once there is sufficient structural support, the hypocotyl emerges from the media in search of light and carbon dioxide. Cotyledons or “seed leaves” offer the first source of photosynthetic tissue as well as protect the first set of “true leaves”. Eventually, cotyledons are consumed and atrophied by the established plant.
Propagation is not often seen in the natural lifecycle of cannabis, but typically utilized in human-controlled cultivation of cannabis. Cuttings are taken of small plant segments that contain meristems or nodes that can differentiate in growth. Cuttings are placed in a consistent environment with warm temperature and high humidity, which promotes hormonal changes in the plant segment. The lower portion of the cuttings will grow roots in 7-21 days and then can be transplanted into larger cultivation systems.
In photoperiod cannabis, the vegetation and flowering stages are controlled by the day length. A typical vegetation length is any 24-hour period that contains 16 or more hours of uninterrupted light. The intensity of this light is less important than the overall length of photoperiod when initiating changes in the cannabis plant. During the vegetative stage, the cannabis plant will solely focus on producing root mass, fan leaves, and meristems or nodes.
The flowering day length is typically 12 hours of uninterrupted light followed by 12 hours of uninterrupted darkness. During the first 2-3 weeks of flowering, the plant will experience a noticeable stem elongation and increased distance between nodes. This period of stem elongation is known as the “stretch” period. During this period, female cannabis plants will also produce an abundance of stigmas, often incorrectly referred to as “pistils”.
After the 2-3 week stretch phase, the female cannabis plants will continue to produce an abundance of reproductive organs, which will effectively “fill-in” the bud sites. This process will continue for 4-8 weeks depending on the specific plant genetics and cultivation methods.
The final 1-2 weeks of flowering is known as the ripening stage. The once white reproductive organs will start to regress and change to an orange color. The trichomes will also start to change from clear, to cloudy, and eventually amber. Cultivators often use magnification tools to visually inspect when plants are ready for harvest. Trichomes do not grow in unison, and thus will be at different stages of ripening. A cultivator has to make an educated decision about when to harvest the crop, using factors such as trichome appearance.
Post-Harvest in Cannabis Cultivation
There are a number of ways to dry cannabis including hanging whole plants, hanging smaller segments of plants, or drying individual buds on racks. In the latter case, the buds will be removed from the main stems immediately after harvest in a technique commonly referred to as “bucking”. Whole plant and plant segments will be dried on the main stems before being “bucked” after drying. Ideal drying conditions can vary, but a good rule of thumb is 60 degrees Fahrenheit at 60% relative humidity for 7-14 days.
Indirect, consistent air flow is important, and moisture should be checked on a daily basis. The size and structure of cannabis buds, as well as environmental parameters, can greatly impact the drying time. Moisture is often checked with a conductivity meter. A moisture reading of 12-15% would indicate the completion of drying.
In the cannabis cultivation process, cultivators have the option to wet-trim or dry-trim. Each option has advantages and disadvantages. Wet trimming includes “bucking” the buds off of the main stems and hand trimming or machine trimming immediately after harvesting. After wet-trimming, the buds will dry on mesh drying racks, because they can no longer be hung by larger branches.
Wet trimming often expedites the drying process, but that may not be ideal for eventual product quality. Dry trimming takes longer than wet trimming, but often produces and more evenly dried and well-preserved product. If the flower is intended to be machine trimmed, wet trimming can be preferred because the product is less brittle. The trim collected from wet trimming is also often a more desirable material for extraction compared to dry trimmed material.
This process involves placing cannabis buds inside a sealed container to achieve the ideal humidity, smell, and taste of the product. The containers will occasionally be opened to allow for gas exchange, or releasing decomposing chlorophyll or excess humidity. This process is often referred to as “burping” and occurs less frequently as the curing process progresses. Also, during this time, chemical changes in cannabinoids and terpenes can take place, leading to a change in the end product.
Biomass containing cannabinoids can be used for extraction where potentially undesirable plant material can be used to make a variety of Marijuana Infused Products (MIPs). This material is often untrimmed, and in some cases, not dried (fresh frozen). Packageable, high-quality flower can also be used for extraction, but extraction material is typically reserved for biomass containing unideal structure, cannabinoid levels, or failed state-required safety screenings.
For more info on cannabis cultivation, check out our post on crop steering.