When to Plant Cannabis Outdoors in Canada: Dates by Region

Last updated: September 2026

Timing is the biggest decision in an outdoor grow in Canada. Put plants out too early and a cold night or short spring days will stall them; too late and a photoperiod strain runs out of summer before its buds finish. This guide gives plant-out windows for every region, city frost dates from Environment and Climate Change Canada, and the indoor start dates that go with them.

It is written for home growers from Victoria to St. John’s, and it covers the legal side too, because two provinces do not allow outdoor plants at all. If you are still choosing seeds, the timing below also tells you which flowering times fit your season.

When is the right time to put cannabis plants outside in Canada?

The right time is when three conditions line up: the last spring frost has passed, night temperatures stay above about 10°C, and days are long enough to keep the plant growing rather than flowering. In southern Canada that usually happens between mid May and early June.

A handy rule in Ontario is to plant out after Victoria Day weekend. On the Prairies, most experienced growers wait for the first week of June. On the BC coast, frost ends much earlier, but cool, wet nights mean mid May is still the practical start.

Why not earlier on the coast?

Vancouver’s average last frost is in mid March, but cannabis put outside in April sees only about 13 to 14 hours of daylight. Young photoperiod plants can start to flower under days that short, then switch back to growth as days lengthen, which costs weeks and yield. Waiting until mid May, when days pass 15 hours, avoids that stall.

What are the frost dates for your city?

The table below uses average frost dates from Environment and Climate Change Canada climate normals (1981 to 2010). An average last frost is the date by which half of years have had their final frost, so a safe plant-out window is one to two weeks after it.

Two things stand out. First, the Prairie season between frosts is often under four months, which rules out long-flowering strains. Second, cities with the same last frost can have very different autumns: Halifax and Kelowna both clear frost in early May, but Halifax keeps frost away three weeks longer in the fall. Local conditions matter too; a downtown yard can be a week or two ahead of a rural valley nearby.

Where in Canada can you legally grow cannabis outdoors?

You can legally grow cannabis outdoors in every province and territory except Quebec and Manitoba. Federally, the Cannabis Act allows up to four plants per household, not per person, as set out in Health Canada’s guide to growing cannabis at home safely. Provinces and municipalities can add their own rules.

• Quebec prohibits growing cannabis for personal use entirely, indoors or out.
• Manitoba has allowed adults to grow up to four plants per household since May 2025, but only indoors, so outdoor plants are still not permitted there.
• Elsewhere, check your municipality and your lease or strata rules; some restrict plants that are visible from the street or require them to be kept away from children.

When should you start cannabis seeds indoors for an outdoor grow?

Start seeds indoors four to six weeks before your plant-out date. That gives you a sturdy plant 20 to 40 cm tall with a strong root system, which handles wind, slugs and cool nights far better than a seedling.

1. Coast and southern Ontario: germinate in mid April for a mid to late May plant-out.
2. Prairies: germinate in mid to late April for an early June plant-out.
3. Atlantic Canada: germinate in late April for a late May to early June plant-out; St. John’s growers can start in early May.
4. North: start in May and plan for a greenhouse or autoflowers.

Keep seedlings under 18 hours of light indoors so they stay in the growth stage, then harden them off for 7 to 10 days before transplanting: start with two hours outside in partial shade and add time each day.

When do outdoor cannabis plants start flowering in Canada?

Outdoor photoperiod cannabis in southern Canada usually starts flowering between late July and mid August, when days shorten to roughly 14 hours of light. The exact trigger varies by strain, and research shows many cultivars begin once days drop below about 14 hours.

From that point the flowering time on the seed packet decides your harvest date. An 8 week strain that starts flowering in early August finishes in late September; a 10 week strain finishes in mid October. That is why flowering time matters more than anything else when you pick outdoor seeds:

Our best outdoor seeds for Canada guide lists strains in each of these groups.

Can you plant autoflowers later, or grow two crops?

Yes, autoflowers can go out later because they flower on age, not day length, and finish 10 to 12 weeks from seed. In southern BC and southern Ontario, some growers plant a first run in late May, harvest it by mid August, and plant a second run in late June.

The second run is the risky one. It finishes in September, when coastal humidity raises the chance of bud rot and Prairie nights can drop to freezing. On the Prairies and in the North, one autoflower run planted in early June is the safer plan. You can browse our autoflowering seeds for fast, compact options.

How cold is too cold for outdoor cannabis?

Any frost can damage cannabis, so plants should not be outside on a night forecast at or near 0°C. Growth slows well before that: below about 10°C at night, young plants stall and roots take up nutrients poorly.

In practice, watch the 10 day forecast after planting and in late September. Fabric pots help, because you can move plants into a garage or under a porch roof on a cold night. Frost cloth or an old bedsheet adds a few degrees of protection. Cold nights in the last two weeks of flower are not all bad; drops to 10 to 15°C bring out purple colour in many strains, as long as they stay above freezing.

What does a Canadian outdoor season look like month by month?

For a photoperiod plant in southern Canada, the season runs roughly like this:

1. March: order seeds and plan your spot; you need 6 to 8 hours of direct sun.
2. April: germinate indoors and grow seedlings under lights.
3. May: harden off, then plant out after frost on the coast and in Ontario.
4. June: Prairie and Atlantic plant-out; top and train plants for a wider canopy.
5. July: peak growth; feed well and water deeply.
6. August: flowering starts; switch to bloom nutrients and support heavy branches.
7. September: buds swell; watch for mould after rain and cover plants on cold nights.
8. Late September to mid October: harvest when trichomes turn milky with some amber.

Our outdoor cultivation guide goes deeper into soil, watering and training for each stage.

Seeds that fit a Canadian outdoor season

• Super Boof: 8 to 9 weeks of flower and purple colour in cool September nights.
• Black Ice: a compact, resin-heavy indica that finishes by early October.

Frequently asked questions

When can I put my cannabis plants outside in Ontario?

Plant cannabis outside in southern Ontario after Victoria Day weekend, when frost has passed and nights stay above 10°C. Toronto’s average last frost is April 30, so late May is a safe margin. Start seeds indoors in mid April so plants are 20 to 40 cm tall at transplant.

When should I plant cannabis outdoors in Alberta?

In Calgary and Edmonton, plant cannabis outdoors in early June. Average last frosts fall between May 21 and May 24, and first fall frosts arrive in mid September, so choose strains that flower in 8 weeks or less or use autoflowers, and start seeds indoors in late April.

When to plant weed outside in BC?

On the BC coast, plant cannabis outside in mid May. Frost ends in March or early April, but days are too short for photoperiod plants before May. In the Okanagan, wait until late May, as Kelowna’s average last frost is May 10 and fall frost can arrive by late September.

Can you grow weed outside in Manitoba or Quebec?

No. Quebec prohibits growing cannabis at home entirely. Manitoba has allowed up to four plants per household since May 2025, but only indoors, so outdoor plants are not permitted. The rest of Canada allows up to four plants per household, subject to local rules.

When do you harvest outdoor cannabis in Canada?

Most outdoor photoperiod cannabis in Canada is harvested between mid September and mid October, depending on the strain’s flowering time and your region. Autoflowers planted in late May finish in August. Check trichomes rather than the calendar, and harvest early if hard frost is forecast.

Every seed we sell is already in Canada: orders ship from Vancouver, BC in plain packaging and arrive in 3 to 7 business days, well ahead of an April germination. Browse our feminized seeds to find a strain that fits your season.