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When to Plant Marijuana Outdoors: A Zone-by-Zone US Calendar
Match your planting date to your USDA zone, last frost and day length, then plan the harvest around your region's fall weather before mold or frost does it for you.
When is the best time to plant marijuana outdoors?
The best time to plant marijuana outdoors is 1-2 weeks after your average last frost, when nights hold above 50°F and the soil has warmed to about 60°F (16°C) at 4 inches deep. Plants set out earlier survive, but cold nights stall growth for weeks and gain you nothing.
USDA zones and frost dates are not the same thing
Your USDA hardiness zone describes the average coldest winter night, not your frost dates. The USDA Plant Hardiness Zone Map is still the most useful starting point because zones track closely with season length. For your exact town, check the last and first frost dates from your county extension office, then use the tables below to plan.
Why day length matters for photoperiods
Photoperiod plants veg while days are long and begin flowering as nights lengthen after the June solstice, usually from late July to mid-August. A photoperiod planted in May has about 10-12 weeks to grow big before that switch. One planted in late June will still flower on the same schedule, just as a much smaller plant.
Autoflowers ignore the calendar
Autoflowers flower by age, so the only question is whether you have about 90 frost-free days after planting. That makes them the flexible option for short northern seasons and for second or third runs in the South.
Last frost and safe transplant dates by USDA zone
Typical windows for each zone. Elevation, coastal influence and microclimates can shift your dates by 2-3 weeks, so treat these as planning ranges.
| USDA zone | Example areas | Typical last spring frost | Safe transplant window | Typical first fall frost |
|---|---|---|---|---|
| 3 | Northern MN and ND, parts of MT and AK | Mid-May to mid-June | Mid to late June | Early to mid-Sept |
| 4 | Northern WI and ME, the Dakotas, much of MT | Early May to early June | Early to mid-June | Mid to late Sept |
| 5 | Southern WI, IA, MI, upstate NY, VT | Mid-April to late May | Late May to early June | Late Sept to mid-Oct |
| 6 | OH, PA, MA, KS, northern IL, Denver area | Early April to mid-May | Mid to late May | Early to late Oct |
| 7 | VA, MD, TN, OK, KY | Late March to late April | Early to mid-May | Late Oct to early Nov |
| 8 | GA, SC, AL, north TX, Seattle and Portland | Early March to early April | Late April to mid-May | Early to mid-Nov |
| 9 | Houston, central FL, Tucson, CA Central Valley | Late Jan to early March | Late April to May (day length, not frost) | Late Nov to mid-Dec |
| 10 | South FL, coastal Southern CA, Phoenix | Rare; Jan to Feb if any | May for full-size photoperiods | Rare |
| 11 | Miami, Florida Keys, Hawaii lowlands | Frost-free | May for full-size photoperiods | None |
Photoperiod vs autoflower plan by zone
Photoperiod harvest dates assume typical 8-10 week hybrids. Sativa-leaning strains finish 2-4 weeks later.
| USDA zone | Photoperiod plan | Autoflower plan | Photoperiod harvest |
|---|---|---|---|
| 3 | Fast-flowering strains only, started indoors 4 weeks early; a greenhouse helps | 1 run: sow in the final pot by early June, harvest late Aug | Mid-Sept |
| 4 | Early finishers that ripen by late Sept | 1 run: sow late May to early June | Late Sept |
| 5 | Most indica-leaning and fast hybrids | 2 runs: mid-May and late June | Late Sept to early Oct |
| 6 | Most hybrids | 2 runs: May and early July | Early to mid-Oct |
| 7 | Most hybrids and many sativa-leaning strains | 2-3 runs: late April, June, late July | Oct |
| 8 | Nearly any strain, including long sativas | 2-3 runs: April through early Aug starts | Oct to early Nov |
| 9 | Plant late April or later so plants veg before flowering | 3 runs: March through Aug starts, avoiding peak heat | Oct to Nov |
| 10-11 | Plant May; plants set out in winter flower almost at once | Year-round, best in the cooler dry season | Oct to Dec |
How to move seedlings outdoors without setbacks
- Start seeds indoors 2-4 weeks before transplantGerminate under lights or in a sunny window so plants go out with 3-5 sets of true leaves and a root system that can handle wind and sun.
- Harden off for 7-10 daysSet plants outside in shade for 1-2 hours on day 1 and add an hour or two of direct sun each day. This hardening-off step prevents sunscald and shock.
- Prepare the hole or containerDig at least 2 ft wide and deep and blend in compost, or use a 15-50 gallon fabric pot. Pick a spot with 8 or more hours of direct sun, ideally morning sun.
- Transplant on a calm, overcast dayPlant at the same depth as the starter pot, water in with about 1 gallon, and mulch 2-3 inches deep to hold moisture and steady soil temperature.
- Protect the first 2 weeksUse a frost cloth if a night below 45°F is forecast, stake young plants against wind, and fence or cage them against rabbits and deer.
How do you plan your outdoor harvest date?
Plan backward from your first fall frost and your region’s rainy season. Photoperiods ripen on a fixed seasonal clock, so the strain’s flowering time decides your harvest week. Autoflowers ripen about 70-90 days after sprouting no matter when you plant.
Photoperiods: pick a strain that beats your weather
Most photoperiod hybrids that begin flowering in early August finish in late September to mid-October. If your first frost or steady fall rain usually arrives before then, choose fast-flowering seeds rated at 7-8 weeks of flowering. A light frost around 32°F can damage leaves and outer buds; a hard freeze below about 28°F ends the season.
Autoflowers: count forward
Add the breeder’s seed-to-harvest time to your sprout date and make sure the result lands at least 2 weeks before first frost. In zone 7, for example, an auto sprouted June 1 with an 80-day cycle finishes around August 20, leaving room for a second run started in early July.
Plug your dates into the harvest date calculator to see the window, then confirm ripeness by trichome color as harvest approaches.
How do you prevent mold and humidity problems by region?
Your region’s late-season humidity matters as much as frost. Bud rot (gray mold) is the biggest outdoor threat in wet climates. Utah State University Extension notes that the fungus is favored by cool temperatures around 65-75°F combined with humidity and rain, and that risk peaks during flower formation after a week or more of humid weather or cool rains.
Pacific Northwest
Summers west of the Cascades are dry, but steady rain often returns by late September or October. Choose strains that finish by early October, give plants a simple rain cover or hoop house for the last 4 weeks, and thin interior growth so dense colas dry out after showers.
Southeast
High humidity, afternoon storms and hurricane season (June through November, peaking August to October) make airflow the priority. Space plants 4-6 ft apart, use lollipopping to remove the lower third of growth, and favor morning sun to burn off dew. Spring autoflowers that finish by July dodge peak storm season entirely.
Southwest
Low humidity keeps mold rare most of the year, but 100°F-plus heat and the July to September monsoon bring their own stress. Use 30-40% shade cloth in the afternoon, mulch heavily, water early in the morning, and watch for powdery mildew during humid monsoon stretches.
Midwest
Humid summers give way to cool, dewy September nights, a textbook setup for bud rot in thick colas. Pick early finishers, plant where morning sun hits, inspect the biggest buds after every rain, and harvest ahead of a forecast week of cold rain rather than waiting out the last few days.
Northeast
Muggy August weather and early fall nor’easters shorten the safe window. Fast-flowering and autoflower strains, generous spacing and a removable rain cover over the final 3-4 weeks are the most reliable combination.
What legal rules affect outdoor growing?
Outdoor home growing is legal only in some states, and many of those set a home-grow limit on plant numbers plus rules that plants be out of public view or behind a locked enclosure. Some cities add their own restrictions on top of state law. Look up your state on our state-by-state hub and read our overview of whether marijuana seeds are legal in the US before you plant, then confirm the current rules with your state’s official cannabis regulator.
This guide is general growing information, not legal advice. Cannabis laws vary by state and locality and change frequently. Verify the current rules with your state's official cannabis regulator before planting.
Plan the rest of your outdoor season
Outdoor planting FAQ
What month should you plant marijuana outdoors?
Most US growers transplant in May or early June. Zones 8-9 can plant from late April, while zones 3-4 usually wait until early to mid-June. Photoperiods in Florida, Texas and Southern California should still wait until late April or May so they have long days to veg before flowering.
Can you plant marijuana outdoors in April?
In zones 7-9, yes, once nights stay above 50°F. In the Deep South, photoperiods set out before mid-April may start flowering early because days are still close to 12 hours long. Autoflowers are a safer April choice there, since day length doesn't affect them.
When is it too late to plant marijuana outdoors?
For photoperiods, planting after early July in most zones produces small plants, because flowering begins in late July to August regardless. For autoflowers, the cutoff is about 90 days before your first fall frost, which is early June in zone 3 and mid-August or later in zones 8-9.
Can marijuana plants survive frost?
A brief light frost around 32°F usually damages leaves and outer buds without killing an established plant. A hard freeze below about 28°F for several hours typically ends the season. Cover plants with frost cloth on cold nights, and harvest ahead of a forecast hard freeze.
When is outdoor marijuana harvest season?
Photoperiod harvest runs from mid-September in the far north to October and November in the South, with long-flowering sativas sometimes into December in frost-free areas. Autoflowers are harvested about 70-90 days after sprouting, so spring-planted autos often finish in July or August.
Should you start marijuana seeds indoors before planting outside?
Yes, for photoperiods. Starting 2-4 weeks before transplant day gives plants a head start and protects them from slugs, birds and cold snaps. Autoflowers are best sown directly in their final outdoor container or bed, since transplanting can cost them growth they can't make up.
What USDA zone is best for growing marijuana outdoors?
Zones 6-9 offer the easiest balance of season length and fall weather for most strains. Zones 3-5 work well with autoflowers and fast-flowering photoperiods. Zones 10-11 allow year-round autoflowers, though summer heat, storms and humidity call for careful strain choice.
How do you prevent bud rot outdoors?
Choose strains that finish before your rainy season, space plants 4-6 ft apart, remove lower interior growth for airflow, and plant where morning sun dries the dew. After heavy rain, gently shake water off branches and inspect the densest buds, removing any gray or brown sections right away.
Find seeds that fit your zone
Every strain spec sheet lists its best USDA zones and climate, so you can match genetics to your season before you plant.