Weed seasons: understanding the best time to grow cannabis in America
Are you thinking about growing your own cannabis? New to being a plant parent? Wondering when you should plant your cannabis seedlings outdoors?
Let’s talk about what “weed season” means in the US, and how you can time your outdoor grow to get the best results.
Photo by: Damien Robertson/Weedmaps
What is weed season?
Weed season is an affectionate term for the eagerly awaited outdoor cannabis growing season, a period that touches our spring, summer and fall seasons.
In the Northern Hemisphere weed growing season can kick off as early as April, when gardeners and farmers might start seedlings indoors. Cannabis plants typically flower in late summer through fall, and the season can run as late as mid-November in warmer climates where some cultivars take a long and luxurious time maturing their buds.
Why do growers plant and harvest cannabis at specific times of the year?
Like any farmer or gardener, cannabis farmers and gardeners typically get their plants in the ground as soon as the weather is warm enough and the days are long enough.
This, of course, varies by region. Farmers in California enjoy generally warmer growing seasons and can plant outside earlier while also harvesting later than, say, New York, whose growing season is shorter on both ends. Regardless of where you’re growing, the main goal is to time planting for maximum light during the summer and maximum growth before fall sets in.
For photoperiod plants, timing is everything. Photoperiod cannabis plants take their cue from Mother Nature (or more specifically the number of uninterrupted hours of darkness) to start flowering. As fall sets in and hours of darkness hit twelve per night, the plant will be triggered into its flowering stage.
There are also cannabis plants that aren’t light-sensitive, called autoflower varieties, that will automatically flower on their own at a particular point of their maturity independent of how much light they’re getting. These plants tend to have much shorter life cycles, which is appealing to some gardeners.
Harvesting happens when the plant’s flowers have fattened up but before the very cold weather comes on, typically by mid to late fall.
Phases of growth and timing for outdoor growers
Speaking of life cycles, let’s talk about the plant’s stages of growth and development. This is where we see the importance of timing once more, since outdoor cannabis growers try to map out the growing season and find the sweet spot for optimal plant development.
Early spring: germination stage Photo by: Gina Coleman/Weedmaps
Early spring: germination stage
If you’re growing from seed, the first step in the life of your cannabis plant is germination. Once the seed has sprouted, it will immediately grow two little round leaves, called cotyledon leaves, that will be responsible for delivering energy to the seedling until it starts to grow the more familiar fan leaves we all know and love.
As far as timing when to sprout your seeds, a general rule of thumb is on or around the Spring Equinox. If you’re not growing from seed but instead buying clones, they’ll already be in the seedling stage when you get them so you don’t have to worry about germination.
Spring to early summer: seedling stage Photo by: Gina Coleman/Weedmaps
Spring to early summer: seedling stage
Seedlings are baby plants. Whether you’ve sprouted your own seed or bought a clone, during this first stage of life the plants are delicate and sensitive.
Folks in cooler climates often elect to start plants indoors to keep them safe and warm, waiting to plant outdoors until they’re somewhere between 6 inches and a foot tall and strong enough to handle the environment outside. Even in warm climates, many growers like to start their plants indoors to give them a leg up since seedlings are susceptible to pests, disease, and mold.
In cooler climates, growers should wait on putting plants in the ground until there is no danger of overnight frost, and plenty of sunshine. As Bill Cook, master grower at Kanna-Wise eloquently put it, “a heavy freeze is killin’ your trees.” An old gardener’s rule of thumb is to move plants outside after Mother’s Day, and they should definitely be outside and/or in the ground by the Summer Solstice.
Of course, you could always grow your plants in pots or containers. Lots of outdoor growers elect to use pots and other containers, and they offer the added benefit of being able to bring the plants out during the day and inside if nights tend to be cold.
Summer to early fall: vegetative stage Photo by: Gina Coleman/Weedmaps
Summer to early fall: vegetative stage
The vegetative stage is when the plant’s growth will really take off. For several weeks, it will grow more foliage, reaching ever upwards to that glorious summer sun.
During this phase, growers might consider topping and training their plants to encourage outward growth. This provides more even distribution of light to the leaves while also managing overall plant height. More water will be needed as the plant develops large root systems and additional nutrients like nitrogen are beneficial as the plant matures.
If you aren’t working with exclusively female plants, you’ll need to get rid of the males before they have a chance to pollinate the females (and wreck your harvest). “Even feminized seeds can have up to 10% males in the mix so it’s important to inspect your plants every day as they start to show their sex. Also important to note is that a stressed female plant can produce male branches or ‘hermaphrodites’, so even if you know she’s a girl, you have to check daily,” advised Sara Rotman, a veteran grower and founder of Wellfounded Botanicals.
A photoperiod plant will continue to live its best vegetative life until the light-to-dark ratio starts to tip in favor of darkness. When photoperiod plants start getting 12 hours of darkness, they will move into their final phase — and perhaps the most exciting for growers — the flowering stage.
Fall: flowering stage Photo by: Gina Coleman/Weedmaps
Fall: flowering stage
For the final stage of a female cannabis plant’s life, most of its energy will be put into producing flowers. The flowering stage happens in three phases:
- Flower initiation: You’ll start to see white, hairy pistils developing, hinting at the buds to come. The plant will continue to grow, but growth will start to slow down.
- Mid-flowering: You will start to see the buds take shape, and the plant will stop growing.
- Late-flowering/ripening: The flowers will really fatten up, becoming sticky and very covered in trichomes. When the pistils turn from white to brown, you can start to think about a harvest.
As the flowers fatten up, they might become too heavy for the branches to handle, and growers often give their plants some help with a trellis, bamboo canes, or another form of support. Extra nutrients like phosphorus are often given during the flowering stage.
Mid-to-late fall: harvest season Photo by: Gina Coleman/Weedmaps
Mid-to-late fall: harvest season
Timing the harvest is an art form in and of itself, though the general rule of thumb is on or around the Fall Equinox. Aside from brown pistils, a close inspection of the trichomes is helpful. Generally, growers look for trichomes that have an amber hue to them. When the plant is ready to harvest you’ll probably also see the fan leaves starting to yellow, curl, and dry out.
Tips for your outdoor grow
Use a grow journal. Tracking the details of your grow efforts, from germination to final cure, will help you become a better cannabis-plant parent. When it’s time for a new season, reviewing the successes and failures from the last crop will make your thumb greener — not to mention improve the quality and quantity of your final harvest. There are lots of ready-made cannabis grow journals out there, but really all you need is a pad of paper and an eye for detail.
Choose a strain for your region or microclimate. Some strains do better in some climates than others, and strain genetics will have a big impact on the growing season. In the northern half of the US where the season is cooler and shorter, growers might want to grow indica-dominant strains, whereas sativas will do well in the more hot and humid southern states that have longer growing seasons. Type of soil, volume of rain, and abundance of sun versus shade are other microclimate variables in your microclimate to consider when choosing a strain.
Plant companions. “Plant beneficial companion plants like marigolds, basil, lemon balm, or lavender. Not only do they invite pollinator insects into your garden, but they also invite beneficial insects like ladybugs and lacewings, which will prey on cannabis pests like aphids,” recommended Natalie Cox, a horticulturist and cannabis educator in Canada.
Keep learning. There is a lot to learn from your budding relationship with cannabis. There are also generations of growers who have shared their experiences, both online and in books. When it comes to cannabis, knowledge plus experience equals wisdom. We have a whole library dedicated to the plant for you to peruse. Luke Fletcher of Fletcher Farms Hemp Company added, “Talk to other growers and farmers in your region. You aren’t going to find all the answers on the internet. Good ‘ole fashion learning from others is a super valuable asset.”
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 cycles 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 to harvest. 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.
When growing outdoors, you’re at the whim of the seasons and will have to wait until the sun starts to go down in the fall for plants to flower, and then to harvest.
However, one way outdoor growers can control the flowering cycle is by using light deprivation techniques.
How long can a marijuana plant live?
Weed plants are annuals, meaning they grow and live for one season and then die. Wild cannabis plants grow seeds and drop them when they die, which will grow into new plants the following year.
When harvesting, plants are cut down and die in order to get their buds. New seeds need to be planted in order to grow more plants.
If left unharvested, weed plants will eventually wither and rot within a few months after the peak flowering phase.
When should you grow marijuana?
If you’re growing outdoors in the Northern Hemisphere, growers usually get their seeds between February and April and start germinating seeds by the end of April.
Many start growing seedlings inside in a more controlled environment because seedlings are more delicate, and then put the seedlings in the ground outside once they’re a little bigger and the weather is warmer.
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.
Harvesting 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; growers in the Pacific Northwest will have to pull down their crops earlier than those in Northern California because of cold weather.
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
Many growers begin germinating seeds as early as February and March in order to have big plants come harvest time, but the Spring Equinox is a good reminder that it’s time to kick off the outdoor growing process and start germinating your seeds if you haven’t already.
Many farmers wait until after Mother’s Day in May to put their plants outside. Just make sure all of your plants are outside by the Summer Solstice at the latest.
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 the Fall Equinox is about when to start harvesting. It’ll depends on your climate and the year—it could happen a little before or after.
Everything should be cleaned up, dried, and curing by Thanksgiving, and in some places, even by Halloween.
As winter approaches, it’s prime 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 next year.
Take meticulous notes on when and how you perform each step, noting:
- How much water you give plants, and at what intervals
- Nutrient amounts
- When you top and prune
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)
Cannabis seed germination
Seed germination length: 3-10 days
Marijuana light cycle: 18 hours a day indoors; full, direct sun 6 hours a day outdoors
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 so the plant can grow 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 in cannabis plants
Seedling stage length: 2-3 weeks
Marijuana light cycle: 18 hours a day indoors; full, direct sun 6 hours a day outdoors
When your marijuana plant becomes a seedling, you’ll notice it developing 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, or “fingers” (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 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 in cannabis plants
Vegetative stage length: 3-16 weeks
Marijuana light cycle: 18 hours a day indoors; full, direct sun 6 hours a day outdoors
The vegetative stage of cannabis is where the plant’s growth truly takes off, and it typically lasts 3-16 weeks. 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 high 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.
Cannabis plant flowering stage
Flowering stage length: 8-11 weeks
Marijuana light cycle: 12 hours a day indoors; full, direct sun 6 hours a day outdoors
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 18 to 12 hours a day.
There are three subphases of the flowering stage:
- 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, as it can upset their hormones
- Plants should be trellised or scrogged so buds will be supported as they develop and air can flow through plants
- Consider giving plants bloom or 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. How long it takes to harvest buds depends on many factors, including harvesting methods and how many plants you harvest.