How Long Does it Take to Grow Weed?

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marijuana plant
Author avatar By Derek LaRose
April 16, 2021
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When asking the question, how long does it take to grow weed, you’re asking a question that needs qualifying with a few more details.

How long does it take to grow cannabis indoors or outside? In soil or hydro? In a greenhouse or on a balcony? Are you growing an auto or a photoperiod?

While there are lots of variables to consider, a good (though broad) answer is this: cannabis plants can take anywhere from 3 to 8 months to grow.

The true answer varies from strain to strain, the type of seed, the growing technique and the climate, though all plants have to pass through four main grow stages.

Understanding grow stages to figure out how long does it take to grow weed

1. Seed Germination (duration: 0 to 5 days)

Cannabis seeds take between twelve hours and five days to germinate, depending on the viability of the seeds and the method of germination used. Some seeds can germinate within a day; others take longer. Healthy seeds are dark in color with stripes or mottling on the shell.

Check our step-by-step “Germination Guide” for further information.

Germinating Cannabis Seeds

Factors that can affect the speed of germination are age and quality of the seeds. Not something you need to worry about when buying from the Homegrown Cannabis Co. You should expect only fresh, premium-quality, hand-picked seeds – Homegrown’s area of expertise.

cannabis seeds in germination stage
Seeds in germination stage

Outdoors, the best time to start your seeds is early April (depending on where you live).

You can learn more about germinating and planting outdoors by checking out Nikki and Swami’s How to Grow Cannabis Outdoors.

2. Seedling Stage (duration: up to 4 weeks)

Once the taproot emerges, it becomes the primary root system. It burrows into the ground to anchor the seed, searching for and absorbing nutrients. Most people plant their germinated seeds in solo cups, filled with potting mix.

The small size of the containers makes watering more manageable. The little starts will soon break the surface and form their first sets of leaves.

Cannabis seedling starts - How long does it take to grow weed
Seedling starts

A common practice among most growers is to keep the seedlings indoors to protect them from the elements. In warmer areas, the seedlings can be moved outdoors straightaway.

3. Vegetative Stage (duration: 4 to 16 weeks)

During the vegetative period, cannabis plants build strong and healthy roots, develop sturdy stems and branches, and form dense foliage.

roots in cannabis plants
Kyle Kushman with a rooted cannabis plant

As a result of this growth spurt, the nutrient, water, and light requirements increase. Towards the end, during the pre-flowering phase, the plants will reveal their gender – an important thing to consider when growing weed from regular seeds.

early vegetative cannabis plants
Kyle Kushman and early vegetative cannabis plants

If growing outdoors, the plants need to be outside by the time of summer solstice (the longest day of the year) in mid-June. This ensures they will absorb all the sunlight they need to photosynthesize. Transplanting cannabis by May or June ensures you’re on schedule.

transplanting vegetative cannabis plants
Transplating vegetative cannabis plants to larger pots
  • Photoperiod cannabis plants will stay in the vegetative stage indefinitely, until the light cycle ‘flips’ to 12/12.
  • Autoflowers are different. After 2 to 4 weeks, depending on the specific strain, they will automatically enter the flowering phase.

4. Flowering Stage (duration: 6 to 12 weeks)

The flowering phase is the final growth stage of cannabis, when the plants divert their energy into developing buds and colas. By now you should stop wondering “how long does it take to grow weed” and start planning for harvest day.

cannabis plant in flowering stage
Cannabis plant in flowering stage
  • Marijuana strains that lean towards Indica usually finish flowering within 7 to 9 weeks.
  • Marijuana strains that lean towards Sativa usually finish flowering within 10 to 12 weeks.
  • Autoflowering and fast versions can finish flowering in as little as 6 weeks.

Photoperiod strains spend seven to twelve weeks in flower and go through three sub-stages (early bloom, mid-bloom, and late-bloom). Approximately four to six weeks after pre-flowering, the pistils will start to turn pink or orange.

It’s only in the seventh to twelfth week that the majority of the pistils will turn dark-orange or brown, an indication the buds are ripe enough for harvest.

Cannabis plant in flowering stage - How long does it take to grow weed
Cannabis plant in flowering stage

After all, how long does it take to grow weed?

How long is a piece of string? Grow with a fast-flowering auto and the entire process could be over within three months. Grow with a photoperiod sativa and you could be looking at the best part of a year.

If you’re wondering how long does it take to grow weed outdoors, you’re at the mercy of the seasons, more than the strain.

If you grow indoors, how long does it take to grow a cannabis plant? This is mostly up to you. You can flip your plants very early in veg (especially useful when deploying a Sea of Green) or you can let them veg indefinitely while you train them pre-flower.

Okay, so how long is the average amount of time it takes to grow weed? We could say 4 months. But if you’ve understood this article, you’ll know that average times mean very little. It’s all about your strains, your set-up and your priorities.

Learn more about growing weed from seed by visiting our blog.


About the author: Derek LaRose

Also known as Kronic from The Cannabis Kronicles, Derek LaRose is a young ambitious cultivator and a staple educator for indoor cultivation.