Cannabis growth is something that requires a lot of patience and curiosity, as the life cycle of the cannabis plant can take anywhere from 3-8 months. During this time, you’ll witness and work through the four stages of a cannabis plant, from germination to flowering until it’s finally ready to harvest, dry, and cure.
Each stage in the cannabis plant life cycle comes with its own special requirements and outcomes, and if you’re planning to start growing marijuana plants, you’ll want to deeply familiarize yourself with the entire process before diving in.
“Every phase of the plant’s life cycle is so important—when you understand the entire life cycle, you can begin to note your success rate, see where you need improvements, and make better scheduling choices for your operation,” explained Evan Marder, Cannabis Community College Professor of Cultivation for the “Cultivation Essentials” course and the President of Fleur Brands.
From lighting requirements and essential nutrients to temperature/humidity levels and pest prevention, there are a lot of things to keep in mind when it comes to cannabis life cycles if you want to ensure you come away with the best, most effective crop possible.
The first piece of the growth cycle a cannabis plant will undergo is germination. During this stage, which can last anywhere from 3-10 days, the required cannabis light cycle will be about 18 hours per day if you’re growing indoors or six hours of direct sunlight for outdoor plants.
Germination is all about the seed: if your cannabis seeds don’t properly germinate, you can forget about growing weed, because it won’t happen. So while this step of the growth process seems straightforward and simple, it’s essential you have all the tools you need to get it right and set yourself up for some great plant growth.
Thankfully, there are quite a few ways to visually track your marijuana seeds throughout germination. Cannabis seeds are usually small, dry, and hard, varying from light to dark brown depending on the strain.
“You always want to let the seeds soak 24 hours before you try and germinate them,” suggested Marder. “The ones that sink to the bottom, they’re good, they’re viable. The ones that sit and float to the top: don’t even bother with those.”
During the cannabis germination stage, the seed shell will be softened by the moist germination conditions: a dark environment with the right amount of water and no added nutrients. If your cannabis seeds appear squishy or green or white in color, that’s a strong indicator that they likely won’t germinate.
Once your seed has germinated, a tap root will emerge, growing downwards and ready to be planted in a growing medium, like soil. You’ll plant it tap root down so the seed’s stem can grow upward and expand. The timing of this is entirely dependent on your seed, the environment your growing in, the strain, and other determining factors, so keep a close eye on things and keep in mind the 3-10-day window.
At this point, two rounded cotyledon leaves will grow from the stem, allowing your plant to unfold from the seed’s protective casing. These initial leaves will take the bulk of your light source or natural sunlight, ensuring the plant grows healthy and well.
As the plant’s root system continues to develop and strengthen, the end of the germination stage is marked, your plant is considered a cannabis seedling, and you’ll find yourself ready to move into the cannabis seedling stage.
The cannabis seedling stage is the second phase in a plant’s life cycle when you’ll begin to notice the development of cannabis fan leaves – a.k.a., the famous five-pronged symbol for the cannabis plant.
The seedling stage will take anywhere from 2-3 weeks, and, similarly to the germination stage, will require 18 hours of light for indoor plants or six hours of direct sunlight per day for outdoor plants.
This is a delicate time for your plant, where blade leaves will be developed – usually anywhere between five and seven for a mature plant – at which point your plant is no longer considered a seedling.
It’s essential that you’re careful about water intake during this stage, especially as the plant transitions from seedling to plant. Your plant is also quite vulnerable to mold, disease, and pests at this stage, so be sure to keep your environment clean, moist (but not too moist), and filled with light sources.
Nutrients are also minimally required at this point, but be prepared to up that intake in the final two stages. In fact, nutrients might be entirely moot at this point depending on your growing medium.
If you’re using a light mix soil, you might not need to add in any nutrients until after your first set of serrated leaves begins showing, as this type of mix generally contains enough nutrition to carry your plant through the first couple of weeks after germination.
On the other hand, if you’re growing hydroponically, you may need to begin a light round of nutrients on your developing seedlings. Either way, your end goal is finding a nutrient sweet spot that neither overfeeds nor underfeeds, so make sure to do your research depending on your specific grow method.
The vegetative or vegetation stage lasts about 3-15 weeks and is considered the real growth stage of the four. Here, your plant will continue to require 18 hours of light per day for indoor grows and six hours of direct sunlight every day outdoors.
This stage is where your plant starts to really thrive, as its roots, branches, and leaves will grow rapidly. You’ll likely need to transfer your plant to a larger pot during the vegetative stage, and you may want to start topping or pruning it as well to guide its healthy expansion.
Your initial sets of fan leaves will continue to develop, and new leaf sets will form. The need for nutrients (specifically nitrogen), water, and light will increase, and you’ll want to start watering further away from the stalk so the roots can stretch themselves out to better absorb the water.
The final phase of growing marijuana is the flowering stage, which lasts about 8-11 weeks. At this point, indoor plants will only require about 12 hours of light per day, but outdoor plants will still require about six hours of direct sunlight.
In the early part of the flowering phase, it’s a good idea to regularly remove dead leaves or struggling buds. Be sure to prune your plants very carefully later in the flowering phase, or you may throw off the plant’s hormone balance and damage its overall effect and continued growth of the plant’s most powerful elements.
Unlike male plants, female plants develop buds and resin-rich trichomes during this stage, which is the most exciting step for a grower to experience. Your hard work will finally be realized, and you’ll be that much closer to your finished product of beautiful flower.
The flowering stage can be categorized into three parts: flower initiation, mid-flowering, and late flowering.
During flower initiation, which occurs during the first 1-3 weeks of flowering, your plant will continue to expand and develop pistils. Then your plant will move to the mid-flowering stage (week 4-5) when the plant will stop growing and the buds will begin to fatten. Finally, late flowering is when trichome density comes into play. Your plants will become sticky and aromatic, filled with white hairs, and will soon be ready for harvest time.
“If you’re getting nice bulbous trichome heads on your cannabis, that’s important,” Marder explained. “It’s actually an indicator of how well you’re doing, and what the plants have been through throughout their lifecycle.”
The life cycle of a cannabis plant is lengthy and somewhat complex, but it provides you with a lot of opportunity as a grower to really understand your crop, how you cultivate, and what your best practices are for quality results.