4 stages of marijuana plant growth
Cannabis plants go through a series of stages as they grow and mature, and those different growth stages call for different amounts of light, nutrients, and water.
It’s important to know these stages and how long each lasts to know what the plant needs and when. Knowing where your cannabis plants are in their life cycle will dictate when to prune, train, and trellis your plants, and when to harvest.
How long does it take to grow a marijuana plant?
Generally speaking, it takes anywhere from 10-32 weeks, or about 3-8 months, to grow a weed plant from seed. It’ll be quicker if you start with a clone or an autoflower seed.
The biggest variability in how long a marijuana plant takes to grow will happen in the vegetative stage—after the seedling phase and before flowering.
If you’re growing indoors, you can force a weed plant to flower after only a few weeks when it’s small, or after several weeks when it’s big. If you’re growing outdoors, you’re at the whim of the seasons and will have to wait until the sun starts to go down in fall for it to flower and then to harvest.
When should you grow marijuana?
If you’re growing outdoors in the Northern Hemisphere, growers usually get their seeds between February and April, and you should start your seeds by the end of April. Some growers will start their seedlings inside in a more controlled environment because seedlings are more delicate, and then put their seeds in the ground outside once they’re a little bigger. If you’re growing clones or autoflowers, you have a grace period of another month or so. Plants usually need to be outside, in the ground, by the end of June.
Harvest happens sometime between September and November. This depends on your local climate, as well as the weather that particular year—one year it could be the end of September, the next, end of October, and growers in the Pacific Northwest will have to pull down their crops earlier than those in Northern California.
If you’re growing weed indoors, you can grow whenever you like. Keep in mind that the outside environment will affect your grow space—you may need to add heaters in the winter or fans and ACs in the summer. Other than that, you can start seeds whenever you like and flip them into flower whenever you like, depending on how big you want the plants.
Important dates for growing marijuana outdoors
The Spring Equinox is a good reminder that it’s time to kick off the outdoor growing process and start germinating your seeds.
As the sun reaches up high in the sky, your cannabis will want to as well. Make sure all of your plants are outside by the Summer Solstice.
The weather will start to turn and the sun will begin descending in the sky as your plants fatten up with sweet, sticky buds. It might be tempting, but wait until around the Fall Equinox to start harvesting.
Everything should be cleaned up, dried, and curing well before the Winter Solstice. Now’s a good time to make your own cannabutter, topicals, or tinctures with all that trim from the harvest. Kick your feet up, relax, and hunker down for the cold, it’s been a long growing season!
Notes on marijuana growth phases
We can’t stress enough that the timeframes in the above graphic are ranges of time for the Northern Hemisphere. You’ll need to adjust them based on your specific region and local weather and climate.
Be sure to keep a grow journal to track the progress of your plants. Looking back on your notes will help you learn from mistakes and maximize the quality and quantity of your buds.
Take meticulous notes on when and how you perform each step, as well as what the weather is like. Other notes can include how much water you give plants, at what intervals, and how much nutrients you give them. Pictures will also give you a better sense of how your plants look along the way.
What are a weed plant’s growth stages?
The growth stages of marijuana can be broken down into four primary stages from seed to harvest:
- Germination (3-10 days)
- Seedling (2-3 weeks)
- Vegetative (3-16 weeks)
- Flowering (8-11 weeks)
Seed germination length: 3-10 days
Marijuana light cycle: 16 hours a day
The first marijuana plant stage begins with the seed. A cannabis seed should feel hard and dry, and be light- to dark-brown in color. An undeveloped seed is generally squishy and green or white in color and likely won’t germinate.
Once your seed has germinated, or sprouted, it’s ready to be placed in a growing medium, like soil. The tap root will drive down while the stem of the seedling will grow upward.
Two rounded cotyledon leaves will grow out from the stem as the plant unfolds from the protective casing of the seed. These initial leaves are responsible for taking in sunlight needed for the plant to become healthy and stable.
As roots develop, the stalk will rise and you’ll begin to see the first iconic fan leaves grow, at which point your cannabis plant can be considered a seedling.
Seedling stage length: 2-3 weeks
Marijuana light cycle: 16 hours a day
When your marijuana plant becomes a seedling, you’ll notice it developing more of the traditional cannabis fan leaves. As a sprout, the seed will initially produce leaves with only one ridged blade. Once new growth develops, the leaves will develop more blades (3, 5, 7, etc.). A mature cannabis plant will have between 5 or 7 blades per leaf, but some plants may have more.
Cannabis plants are considered seedlings until they begin to develop leaves with the full number of blades on new fan leaves. A healthy seedling should be a vibrant green color.
Be very careful to not overwater the plant in its seedling stage—its roots are so small, it doesn’t need much water to thrive.
At this stage, the plant is vulnerable to disease and mold. Keep its environment clean and monitor excess moisture. Be sure to give it plenty of light.
Even if growing outdoors, a lot of growers will start their seeds inside under an artificial light to help them through this delicate stage of marijuana growth.
If you buy a clone from a grower or breeder it will be a seedling, so you can skip the seed germination phase.
Vegetative stage length: 3-16 weeks
Marijuana light cycle: indoor—16 hours a day; outdoor—at least 8 hours of direct sunlight (“full sun”), plus several hours indirect sunlight
The vegetative stage of cannabis is where the plant’s growth truly takes off. At this point, you’ve transplanted your plant into a larger pot and the roots and foliage are developing rapidly. This is also the time to begin topping or training your plants.
Be mindful to increase your watering as the plant develops. When it’s young, your plant will need water close to the stalk, but as it grows the roots will also grow outward, so start watering further away from the stalk in the soil so roots can stretch out and absorb water more efficiently.
Vegetative plants appreciate healthy soil with nutrients. Feed them with a higher level of nitrogen at this stage.
If you need to determine the sex of your plants (to discard the males), they will start showing sex organs a few weeks into the veg stage. It’s imperative to separate males so they don’t pollinate the females.
Flowering stage length: 8-11 weeks
Marijuana light cycle: 12 hours a day
The flowering stage is the final stage of growth for a cannabis plant. This is when plants start to develop resinous buds and your hard work will be realized. Most strains flower in 8-9 weeks, but some can take even longer, especially some sativas.
Outdoors, flowering occurs naturally when the plant receives less light each day as summer turns into fall. Indoor growers can trigger the flowering cycle by reducing the amount of light marijuana plants receive from 16 to 12 hours a day.
Within the flowering stage, there are three subphases:
- Flower initiation (week 1-3): The plant will continue to grow and females will develop pre-flowers—pistils, or white hairs, will grow out, which are the beginnings of buds.
- Mid-flowering (week 4-5): The plant itself will stop growing and buds will start fattening up.
- Late flowering/ripening (week 6 and on): Trichome density will increase and plants will get very sticky; keep an eye on the color of the pistils to tell when to harvest.
There are a number of changes to consider once plants go from the vegetative stage to the flowering stage:
- Don’t prune when plants are flowering stage, as it can upset their hormones
- Plants should be trellised so buds will be supported as they develop
- Consider giving plants bloom (phosphorus) nutrients
When do buds grow the most?
Buds typically grow the most toward the end of the flowering life cycle. You probably won’t notice much budding out at the beginning of the flowering stage, and it will slow down toward the end of the cycle, when buds become fully formed.
Once buds have reached full maturation, it’s time to harvest your marijuana.
Pat Goggins and Trevor Hennings contributed to this article.
Knowing where your cannabis plants are in their life cycle will dictate when to prune, train, and trellis your plants, and when to harvest. Learn more about marijuana growth stages today.
When To Switch Your Cannabis Grow From Vegetative To Flowering
When switching cannabis plants from the vegetative stage to the flowering stage, growers need to be aware of numerous considerations. Making the switch at the right time is crucial to maximising yield and avoiding complications.
Knowing when to flip your grow from the vegetative to the flowering stage is one of the most important factors to ensure the success of your plants. This is because making the switch too early can result in a smaller total yield. Conversely, making the switch too late can result in overgrowth, or burned buds. The decision to make the switch should be based on the careful consideration of numerous factors such as the age of the plant, the maximum height that the plant can obtain within your setup, the type of strain(s) being grown, the source of the plant (from seed or clone), and the growing method being employed.
When making the switch, growers need to be aware of all of these conditions, and of the ways in which they can affect the final product. Since each grow is unique, growers should be careful when copying the methods and techniques used by others. They may actually end up giving you dramatically different results than what you intended.
DOES PLANT AGE MATTER?
Sort of—not really. Some growers believe that plants grown from seeds must be given 60 days of maturation in the vegetative state. However, this is not necessarily true. It is important to remember that young seedlings cannot start properly flowering for 2–3 weeks. However, when growing from clones, age is not an issue. Growers can switch to the flowering stage as soon as the clone has established a solid root system.
In optimal conditions, plants should be kept in their vegetative stage for approximately 60 days. This time period should give the plant the opportunity to maximise yield and acclimatise to growing conditions. This is important because complications and mistakes are much more difficult to recover from during the flowering stage. It should be noted that this time period is just a recommendation. If maximum yield is not a priority, or if growing conditions will not permit for a lengthy vegetative stage, plants can be flowered long before the 60-day benchmark.
FACTOR #1: MAXIMUM PLANT HEIGHT
The most important consideration is the amount of space available for your plants. The longer that plants are kept in a vegetative state, the taller they will become. As such, vegging your plants for too long in a confined space can result in an overgrow situation. Plants that grow too high can potentially reach too close to light fixtures and suffer damage as a result. Ideally, you should never let your plants reach closer than 30cm from the lights above them. This is a rough estimate. However, growers risk burning or frying their buds if they allow them to reach any closer.
Be sure to consider the light fixtures being used in the grow. Some bulbs glow hotter than others, and this will certainly affect the minimum distance that should be kept between the plants and the lights. How long you let your plants grow in their vegetative state should also depend on the kind of strain that you are growing.
FACTOR #2: STRAINS—INDICA OR SATIVA?
The genetic differences between indica and sativa strains must be considered when making the switch to the flowering stage. That is because indicas and sativas behave differently during flowering. Indica strains are known for producing shorter, thicker, bushier plants when compared to their sativa counterparts. Typically, they will gain only 25–50% of their height in the flowering stage. By comparison, sativas are known for their height, and for their ability to keep growing taller throughout the flowering stage. They have been known to double their height from the first day of flowering until harvest.
Keep in mind that these characteristics apply to pure sativa and indica strains. Most strains will demonstrate characteristics representative of both kinds since they are not 100% indica or sativa. When dealing with hybrids, make sure to research the genetic makeup of the plant so as to have a better idea of what to expect during the grow. A basic rule of thumb for growing hybrids is to expect that the plant will grow to be twice the height it is at the end of its vegetative state.
FACTOR #3: CLONES OR SEEDS?
The planting method chosen for the grow will also affect the timing of the switch. The difference between growing from seeds or clones will affect the growth rate of the plant’s root system. If the plant has not established a solid root system, then there may be issues and complications during the flowering stage.
Clones can grow very tall very quickly, forcing growers to make the flip to flowering based on plant size alone. However, growers should make sure to give their clones the necessary amount of time to establish themselves before flowering. Seedlings can be flowered much earlier, but remember that they will require 2–3 weeks before being able to do so.
FACTOR #4: GROWING METHODS
Different growing methods such as the sea of green (SOG) method, the screen of green (ScrOG) method, lollipopping, and super cropping can all affect the switch. Depending on which method you choose, your flowering time will likely be different.
- Sea of Green (SOG)
This method relies on flowering plants early so that they only produce one large bud. This method is usually employed with indica strains that are packed tightly together in the grow space. When using this method, plants should be flowered when they reach a height of between 15–30cm.
- Screen of Green (ScrOG)
This method utilises a mesh screen that is layered horizontally above the plants. The screen is typically placed 30–60cm above the base of the plants. This allows them to grow right through it. When using this method, plants must remain in a vegetative state for several more weeks than with the SOG method.
Lollipopping is a technique that involves removing the lower growth of the plant that receives very little to no light. Because plants need light to grow, these regions will produce smaller buds and drain the plant of energy that could be better spent elsewhere. By removing the lower leaves and bud sites, the plant can focus its energy on the upper colas that grow denser, thicker nugs. This method typically involves a height-based flowering switch. Sativas are usually switched when they reach 30–45cm, since they grow so much during the flowering stage. Indicas are switched when they reach a height of around 100cm, giving them more time in the vegetative state.
- Super Cropping
This method is designed to produce very heavy yields from a minimal number of plants. As such, plants grown using this technique need to remain in the vegetative stage for longer. Super cropping involves bending upper branches down so as to allow more light to reach the lower parts of the plant. This keeps the height of the plant in check throughout the grow, and allows for a longer vegetative period.
Typically, outdoor growers allow their plants to flower by themselves. This usually occurs after mid-summer when days become shorter than 12 hours. Outdoor growers should take care to ensure that their plants do not receive any kind of light at night. This includes light sources such as garden lights, street lights, or spotlights.
However, outdoor plants do not necessarily need to be left to their own devices. Similarly to indoor plants, they can also be forced to flower by a change in conditions. Some climates simply do not offer plants enough time to flower before winter. Other climates may require a grower to force flowering so as to keep the plant in check. Additionally, some growers choose to force flowering in order to harvest multiple grows during the same season.
Whatever the reason, forcing outdoor plants to flower is a simple process. Outdoor growers usually force flowering by covering up their plants, reducing their exposure to sunlight as a result. Cultivators using greenhouses simply need to cover the windows of their grow room.
WHAT TO EXPECT WHEN FLOWERING
For most cannabis strains, the flowering period will last somewhere between 7 to 10 weeks. What happens during this period will vary from week to week and strain to strain. For more information about what you can expect during the flowering period, check out the week-by-week Royal Queen Seeds flowering guide.
Switching your cannabis plants from the vegetative stage to the flowering stage requires careful consideration of several important factors.