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The honest answer to how long to grow cannabis is somewhere between three months and seven months, depending on whether you picked an autoflower or a photoperiod, whether you are growing indoors or out, and how patient you are about the part everyone forgets: drying and curing. The forum answer of “about four months” is roughly true for the fastest autos and totally wrong for a slow sativa-leaning photoperiod outdoors in Ontario.
This post lays out how long to grow cannabis stage by stage, with realistic week counts for each phase, the difference between autos and photoperiods, and the practical reasons your timeline will slip from the box-art numbers. If you are buying seeds and trying to plan when you will actually have dry, smokable flower, this is the page that should answer it.
How long to grow cannabis from seed to jar, in plain numbers:
The single biggest variable in how long to grow cannabis is the seed-type decision. The choice of autoflower vs photoperiod shifts how long to grow cannabis by months, not weeks. Autoflowers run on an internal clock and finish in roughly the same number of weeks regardless of your light schedule. Photoperiods are slaves to day length and can be held in vegetative growth for as long as you want before you flip them. That choice alone can swing your timeline by two months, which is why the autoflower vs feminized decision is the first thing to settle before you buy.
Germination is the first leg of how long to grow cannabis from seed, and it is the cheapest leg to get wrong. You start with a dry, dormant seed and end with a taproot punched out and a baby plant in soil or media. Most healthy cannabis seeds germinate in 24 to 72 hours using the paper-towel method or direct-to-soil. Older or harder-shelled seeds can take five to ten days. Anything past ten days is usually a dead seed.
The germination phase does not look like a lot of progress, but the plant is doing real work — pushing the taproot down, cracking the shell, getting the cotyledons (the two embryonic leaves) above the medium. We covered the actual mechanics in our germinating cannabis seeds guide. The short version: warm (22-26°C / 72-78°F), dark, moist but not wet, no nutrients. If your seeds are not popping, the problem is almost always temperature or moisture, not the seeds themselves.
Time added to total grow: 3-10 days. Call it one week for planning.
From the moment your sprout breaks the surface until it has three to five sets of true leaves and an established root system, it is in seedling stage. This is where new growers panic the most and where most timelines start to slip. Seedlings look fragile and they grow slowly. That is normal. The plant is building roots before it builds canopy.
Seedling stage typically runs 14 to 21 days. Light should be moderate (18 hours on for both autos and photos at this stage), nutrients should be either nothing or very light, and humidity should be on the higher side (60-70%). If you push a seedling with strong light and full-strength feed, you will stunt it and end up adding a week to how long to grow cannabis overall — not saving time.
Time added: 2-3 weeks. Running total: 3-4 weeks from seed.
This is where the auto vs photo split changes how long to grow cannabis dramatically.
A photoperiod plant on an 18-hour light schedule (or long natural summer days outdoors) will stay in vegetative growth indefinitely. You decide when to flip it to 12/12 indoors, or the shortening day length triggers it outdoors. Most indoor growers veg for 3-6 weeks after the seedling stage, sized to the tent. Outdoor growers in the Northern Hemisphere veg from May through July — roughly 10-14 weeks of vegetative growth before the natural flower flip in late July or August.
If you have a small tent, short veg keeps plants manageable. If you want bigger yields, longer veg builds the frame the flowers will sit on. Either way, this stage is the most flexible piece of how long to grow cannabis for photoperiods.
Autoflowers do not care about your light schedule. They start flowering when the plant itself decides, usually around week 3-4 from seed. You cannot extend veg on an auto by giving it more light hours. Whatever frame the plant has built by week 3-4 is the frame it will flower on. That is why autos are smaller and faster: the plant is structurally committed to its own clock.
Time added for vegetative: 3-6 weeks for indoor photos, 3-4 weeks for autos, 10-14 weeks for outdoor photos. Running total: 6-18 weeks depending on path.
Flowering is where the plant actually makes the flowers you came for. The stretch — that 2-3 week growth spurt right after the flip — happens in the first half of flowering. The bud development, swelling, and trichome ripening happen in the second half. This is the most resource-intensive phase, and how you feed and light the plant here decides most of the final quality.
Flowering timelines by strain type:
One nuance buyers miss: the “flowering time” attribute on photoperiod product pages is the flowering phase only. The “flowering time” on autoflower product pages is the entire seed-to-harvest window. Always read the description text to confirm which clock the breeder is using.
The end of flowering is decided by trichome color, not by a calendar. We wrote the long version in our when to harvest cannabis guide — the short version is to check trichomes at 30-60× magnification and harvest when most are milky white with a small fraction amber. Most growers extend flowering by a week beyond the breeder’s listed time. That is normal.
Time added: 8-14 weeks for photoperiods, 5-7 weeks for autos.
This is the stage that blows up most beginner timelines for how long to grow cannabis. You spent months growing the plant. You are not finished when you chop. You are finished when the buds are dry and cured.
Plan for 3-6 weeks total between chop and the first joint you actually enjoy. Cannabis can be smoked off a 7-day dry — it will not taste good and the smoke will be harsh. Skipping the cure is the single most common reason new growers think their bud “is fine but not amazing.” It is the cure, not the genetics.
Time added: 3-6 weeks. Running total: see the table below.
Two paths, real numbers, fastest realistic end-to-end for each:
| Stage | Autoflower (indoor) | Photoperiod (indoor) | Photoperiod (outdoor NH) |
|---|---|---|---|
| Germination | 3-7 days | 3-7 days | 3-7 days |
| Seedling | 2-3 weeks | 2-3 weeks | 2-3 weeks |
| Vegetative | ~3-4 weeks (auto) | 3-6 weeks | 10-14 weeks |
| Flowering | 5-7 weeks | 8-12 weeks | 8-12 weeks |
| Drying + curing | 3-6 weeks | 3-6 weeks | 3-6 weeks |
| Total | 10-15 weeks | 14-22 weeks | 5-7 months |
Worth saying again: how long to grow cannabis is dominated by two choices — auto vs photo, and indoor vs outdoor. Get those right for your timeline and the rest is execution. If you want bud in your jars before the snow flies and you are starting in July, an autoflower indoors is the only realistic answer. If you have all summer and a backyard, an outdoor photoperiod will give you the biggest yield for the least input.
The same seed in an indoor tent and in a backyard plot will not take the same amount of time. Outdoor plants veg longer (the natural day length keeps them in growth from May through late July), flower on the sun’s schedule (August-October), and finish later than the breeder’s indoor numbers suggest. A photoperiod listed as “9-week flowering” indoors typically pulls 10-11 weeks of flowering outdoors because nights are not as deep early in flower.
Indoors, you control everything: 18/6 for veg, 12/12 for flower, room temperature steady, humidity managed. The breeder’s listed flowering time is reasonably accurate. Outdoors, the plant runs on the sun and the climate. Plan for an extra one to three weeks past the indoor number, especially in the northeast of Canada or the cooler parts of the Eastern US where late-season rain and cold can push the harvest window dangerously close to first frost.
This is also why first-time outdoor growers should heavily favor autos or fast-flowering photoperiods. If your photoperiod needs 11 weeks of flowering and your first frost is October 5, you need that plant to flip into flower no later than mid-July. Cutting it close on how long to grow cannabis outdoors is how you end up harvesting wet, moldy buds in a thunderstorm.
Three real-world reasons how long to grow cannabis ends up longer than you plan:
The Canadian Cannabis Act caps home cultivation at four plants per household, which has a side effect on timelines: with only four plants, you cannot run a perpetual harvest, so the calendar matters more. Pick strains whose timelines actually fit your season. (For the legal text, see Canada’s Cannabis Act.)
If you want to finish fast, the strain itself does a lot of work. Picks at different points on the timeline curve:
Browse all autoflower seeds or all feminized seeds to filter by flowering time on the product pages.
Ten to fifteen weeks from seed to cured bud is the realistic range for indoor autoflowers. The fastest strains like White Widow Auto can finish in about ten weeks of growth plus three weeks of drying and curing.
Five to seven months for photoperiod outdoor grows in the Northern Hemisphere: seeds started indoors in April-May, transplanted out in late May or early June, flowering through August-September, harvested September-October, cured through October-November. Autoflowers outdoors finish faster — about three months from transplant.
Modestly, yes — pick a fast-finishing auto, run optimal environment indoors, and do not skimp on the cure. You cannot shortcut the cure without ruining the result. Cutting two weeks off a 14-week grow is realistic. Cutting four is not.
Two reasons. First, breeders test under near-perfect indoor conditions; your environment is rarely that clean. Second, the listed “flowering time” rarely includes drying and curing, which add three to six weeks on the back end. Build those weeks into your plan from the start.
Total elapsed time, yes — outdoor grows include 10-14 weeks of vegetative growth driven by the long summer days, where an indoor grower might only veg 4 weeks. Flowering itself often runs slightly longer outdoors as well. Net: outdoor totals are usually 5-7 months versus 4-5 months indoor.
How long to grow cannabis from seed to a jar of cured flower depends on the path you pick. How long to grow cannabis is realistically 10-15 weeks for the fastest indoor autoflowers, 14-22 weeks for indoor photoperiods, and 5-7 months for outdoor photoperiods in North America. The single biggest lever is auto vs photo. The single most underestimated leg is drying and curing. Plan for both honestly and the rest is craft.
If you are matching a strain to a season or a tent size, start with how to choose cannabis seeds, then narrow by flowering time on the product page. The answer to how long to grow cannabis is always strain-specific in the end — there is no universal number that beats reading the actual product page of the strain you are about to grow.
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