Now that cannabis is becoming mainstream, botanists have an easier time obtaining the plant to study its unique growth cycle.
Although there are slight variations between species, scientists now know cannabis is a photoperiod-sensitive plant that usually goes through four stages before harvest. Depending on the strain, this process could take anywhere between 4 – 8 months.
Let’s take a closer look at these four stages from cannabis seed to flowering. Below, we’ll also briefly explain the genetic reasons why autoflowering cannabis seeds aren’t light-sensitive.
Getting Started With Germination
The first phase of growth for cannabis is known as germination. In this stage, growers slightly wet hearty seeds to encourage “taproots” to bust out. These tiny, white taproots will serve as the basis for the plant’s sturdy root structure.
As long as cannabis seeds remain dry, they will not express roots. Only after a seed comes into contact with water will the embryo start to swell and eventually bust through the seed’s tough outer shell.
Seeds could start showing these taproots as early as 24 hours, but it usually takes at least a few days before they appear. Once the taproots are clearly visible, the seeds should be planted in small containers to encourage the next phase of growth.
Springing To Life As A Seedling
After planting the germinated seed, the taproot will get to work building a root network to draw in nutrients and establish stability. At the same time, the plant’s first green stem will slowly work its way upward.
The first two rounded leaves on this green stem are known as cotyledon leaves. These leaves are extremely significant as they signal the plant can begin photosynthesising light into energy.
Speaking of light, seedlings typically require a strong light source that’s fairly close to the stem. Since the root system isn’t robust yet, seedlings can’t stretch too far towards the light without seriously injuring themselves. Seedlings also don’t need as much water or nutrients as in other stages because the fragile root system can’t handle it.
From this point on, the seedling will continue growing, and the iconic fan leaves will begin to emerge. Usually, growers mark the end of the seedling phase when they see an average of five to eight fingered fan leaves. This process could last anywhere from 1 to 3 weeks.
Taller And Taller: The Vegetative Stage
The vegetative stage is all about growth. This is the time in the plant’s life cycle when it really develops and demands nutrients. The plant’s stem will start to thicken during vegetation, and more branches with distinctive fan leaves will begin to burst out. Plants during vegetation typically require high amounts of nitrogen and about 16 hours of light per day.
Interestingly, a vegetative plant’s fan leaves might change colour as it continues to grow. Sometimes this change is natural in certain strains, but other times these colours may signal nutrient deficiencies.
At the tail end of the vegetative stage, the cannabis plant will also begin expressing its sex. Male plants will have pollen sacs in nodes while females will have hair-like strands. Those with both of these features may be hermaphrodite plants and are treated as males.
There’s no set time for cannabis vegetation, but usually, this stage lasts between 2 – 9 weeks. The only way to tell when to switch into flowering depends on information specific to that strain (e.g. average time, average height, etc.). Indoor growers manually switch from vegetation to flowering by reducing the amount of light exposure these plants receive.
Once growers switch to a 12-hour light schedule, the flowering stage will begin automatically. During this last phase, the cannabis plant will finally produce its aromatic, resinous buds over a period of about 6 – 8 weeks.
The decreased light triggers a unique hormonal change in un-pollinated female plants that causes them to divert all energy towards the buds. This translates to increased trichomes full of cannabinoids and terpenes.
Flowering plants usually require less water and less nitrogen than vegetative plants. The flowering plant also tends to absorb more phosphorus and potassium.
As the flowering stage further develops, the sticky trichomes will start to change colour. At first, trichomes look clear, which signals they are still quite immature. Once these trichomes look milky white, however, it marks it has reached peak cannabinoid content. As trichomes continue to oxidise, they will start to transform into an orange/amber colour. This late-stage colour indicates the THC is breaking down into another a cannabinoid known as CBN. Growers usually harvest the cannabis plant when it’s in-between the milky white and orange phases.
A Brief Note On Autoflowering Seeds
As a quick aside, autoflowering seeds don’t develop in the same manner described above. These fast-flowering seeds owe part of their genetics to a lesser-known cannabis variant called ruderalis.
Growing up in harsh northern environments, ruderalis cannabis developed the ability to flower without the need for specific photoperiods. So, when ruderalis genetics are crossed with indica or sativa strains, they produce plants that can reach peak maturity regardless of lighting conditions.
While auto seeds are certainly faster non-auto seeds, they tend to grow short in stature and have less overall yield. Also, the buds from auto seeds don’t produce as potent trichomes.
The Cannabis Life Cycle: So Much More To Discover
As we mentioned above, every cannabis strain has its own unique features and grow time. In general, however, the cannabis strain should follow the four major phases listed in this article. As scientists are better able to study different cannabis varieties, hopefully, we’ll learn more about this plant’s unique growth cycle and optimal cultivation.