How Long Does It Take to Grow Weed Outdoors?

Sophia Delphi June 08, 2022 - 7 min read
Fact Checked
Marijuana plants grown outdoors

Let’s start with a different question: how long does it take to make dinner?

If you’re nuking a Hot Pocket, about two minutes. If you’re making a box of mac-and-cheese, around eight minutes once the water is boiling. But if you’re making a pot roast in a slow cooker, you’d better allow 4-8 hours or so.

The answer to the question “how long does weed take to grow outdoors?” is essentially the same as it is for making dinner: it depends.

In most cases, it can take anywhere from five to eight months before your outdoor plants are ready to harvest, although that time frame may be shorter or longer for some plants.

Why such a difference? The type of plants you’re growing, the strains you’ve chosen, and where you live will largely determine whether you’re going to have a relatively short growing season or one which will last throughout the spring, winter, and fall.

Let’s sort out the possibilities.

The Four Stages of Cannabis Growth

Whether you’re growing indoors or out, all weed plants go through four distinct growth stages.

  • Germination: When new seeds open and form taproots.
  • Seedling: When the first leaves appear, and real plant growth begins.
  • Vegetative: Plants grow large, and all of their fan leaves appear.
  • Flowering: Growth slows dramatically as buds appear and flourish.

Each of those stages (except for germination) lasts for a number of weeks — but the exact number depends on all of the factors we mentioned at the start.

You can eliminate the germination stage by starting your outdoor grow with clones, and there are a few techniques that may let you shorten the growth process.

However, you’re pretty much at the mercy of the environment and climate, so be prepared to settle in for a full growing season.

Growing Outdoor Weed: Uncontrollable Variables

There are very few cannabis plants you can grow outdoors with the hope of ending up with a harvestable crop in two or even three months. We’ll discuss the best choices for impatient readers shortly.

First, though, it’s important to understand what external factors determine the length of a weed plant’s growing season.

Cannabis plants, like almost all types of plants, grow best in ideal conditions. That means high or low temperatures, droughts, or rainy seasons can shorten or prolong their growing period.

Unseasonable heat or drought can cause weed plants to wilt, meaning their growth will slow or even stop. Hotter-than-usual temperatures may not have that drastic an effect but can lead to reduced trichome production and less-potent product. Unusually heavy rainfall or cold temperatures can cause mold growth, root rot, or retarded growth.

The best way to ensure that growing periods aren’t stretched out longer than usual? Choosing strains that grow best in your specific climate and environment and being careful to grow hardier plants in areas where extreme climate conditions often occur.

Otherwise, the length of time your weed takes to grow could exceed normal ranges — running right into fall weather that could damage or kill the plants.

Growing Weed Outdoors: Genetics and Strains

Sativa plants are likely to take longer to finish growing than indicas, and the reason is genetics.

Sativas grow much taller than indicas, and producing bountiful colas on that size of plant requires more time and energy. They may spend the same amount or even less time in the vegetative stage but will take much longer to complete the flowering stage.

The typical sativa plant remains in the latter stage for 10-12 weeks and may not be ready to harvest for 16 weeks. Indicas, by contrast, bush out instead of growing tall. That means they flower more efficiently, so their flowering stage generally lasts between 6-10 weeks. Hybrids can fall anywhere in between sativas and indicas, depending on their dominant genetics.

So when you add in the amount of time required for the germination, seedling, and vegetative stages, you can expect your weed plants to need anywhere between 12-24 weeks from start to harvest. It will usually be on the shorter end of that time frame for indicas and hybrids and the longer end for sativas.

Those numbers are only approximate, though, because the plant’s strain also plays a major role — and not all indica, sativa, and hybrid strains have the same genetics.

Some strains are known for flowering relatively quickly; they’ve usually been bred from at least one parent native to areas with short growing seasons. Strains like Candy Kush Express and Royal Cheese, for example, have been known to spend just 6-7 weeks in the flowering stage.

There’s an even better way to ensure shorter flowering stages and growing cycles than choosing one of those strains, however. It has to do with something called autoflowering.

Photoperiod vs. Autoflower Cannabis Plants

Most weed plants are “photoperiod” plants.

In short, they take their growth cues from light. More specifically, they’ve been genetically “programmed” to switch to the flowering stage when days start to get shorter, and there’s less sunlight available. Indoor growers can jumpstart flowering by reducing the amount of light their plants receive — but obviously, outdoor growers can’t control the sun.

Here’s the solution. Some strains are bred to be “autoflowering” plants, which automatically switch from the vegetative to the flowering stage after a certain number of weeks, regardless of how much light they receive.

And planting autoflowering strains can make a dramatic difference in how long it takes weed to grow outdoors.

These plants grow smaller than photoperiod strains and usually contain less THC, but they progress from germination to harvest at lightning speed (for cannabis plants). The entire growth cycle will last just two to three months for most autoflowers.

Some of the fastest-growing autoflowering strains are Sour Crack Auto, Sweet Skunk Auto, Purple Cheese, and Lowryder, each of which may produce harvestable bud in just eight weeks.

Autoflowers are great choices if you want to produce multiple crops each year if you live in rugged climates with a very short growing season, if you’re planting late in the year — or if you’re just understandably impatient to enjoy the fruits of your labor.

How Long Does Weed Take to Grow Outdoors: FAQ

Q: Is there any way to force photoperiod plants to flower more quickly if they’re outdoors?
A: Indoor growers have a clear advantage since they can simply alter their plants’ light schedule. When plants are outdoors, it’s possible to cover them with a large tarp with sides that restricts the amount of direct sunlight they receive. It won’t be as effective as growing indoors, but it may help; just be sure the plants still receive decent airflow, or they may be prone to growing mold. One other option: grow in pots, and move the pots indoors for 4-6 hours each day.

Q: If I grow autoflowers, does that mean I can have bud ready to smoke in just 2-3 months?
A: Not really, since the plants will still have to be dried and cured after they’re harvested. That will add another month or so to the final timeframe. Sorry about that.


Roeber, V. M., Schmülling, T., & Cortleven, A. (2021). The Photoperiod: Handling and Causing Stress in Plants. Frontiers in Plant Science, 12 [1].

Petit, J., Salentijn, E. M., Paulo, M. J., Denneboom, C., & Trindade, L. M. (2020). Genetic architecture of flowering time and sex determination in hemp (Cannabis sativa L.): a genome-wide association study. Frontiers in plant science, 1704 [2].