What to Plant in May in Canada | Zone-by-Zone May Garden Guide

May is the most important planting month for Canadian gardeners. Frost danger drops zone by zone, soil warms up, and the bulk of warm-season vegetables go into the ground. But what you can plant in May depends heavily on where you live — a zone 3 gardener in northern Ontario is still watching the forecast while a zone 8 gardener in Victoria is already harvesting spring greens and transplanting tomatoes.

Use this guide to find exactly what to plant in May by zone, with province context.

Short on time? Use the free planting date calculator at MyGardenPlanner.ca to get personalized planting dates for your exact location.

What Determines May Planting in Canada

Your last frost date is the key. Most warm-season vegetables can't go outdoors until after your last frost. Here's the general last frost window across Canada in May:

Not sure of your zone? Check the Canada Hardiness Zone map.

Zone 3 — What to Plant in May (Northern Ontario, Central Prairies)

In zone 3, May is still a split month: cool-season crops go in early, warm-season crops wait for the frost-free window in late May.

Direct sow outdoors (early May):

• Peas — 2.5 cm deep, 5 cm apart in double rows
• Spinach (bolt-tolerant varieties like Space or Tyee), lettuce, radishes, kale, Swiss chard
• Carrots, beets (pre-soak seeds 4–6 hours), parsnips

Start indoors (for June transplant):

• Tomatoes (if not already started), peppers, squash, cucumbers

After May 20 (once frost risk drops):

• Direct sow beans, corn, squash seeds outdoors
• Transplant hardened-off brassicas (broccoli, cabbage, cauliflower)

Zone 4 — What to Plant in May (Southern Prairies, Parts of Alberta)

Zone 4 covers southern Manitoba, Saskatchewan, and much of Alberta. Last frost typically falls May 1–15, so mid-May is when warm-season planting accelerates.

Early May (still frost-watch):

• Direct sow peas, spinach, lettuce, beets, carrots
• Transplant cold-hardy starts: broccoli, cauliflower, kale

After May 15:

• Direct sow beans (3–4 cm deep, 8 cm apart, rows 40 cm apart), corn, sunflowers
• Transplant squash, cucumbers after hardening off
• Tomato and pepper transplants after your confirmed last frost date — consider black plastic mulch to boost soil temperature for peppers

Zone 5 — What to Plant in May (Ottawa, Montreal, Southern Ontario)

Zone 5 covers a large portion of Canada's most populous gardening region. Last frost typically falls May 1–10, making mid-May the "go time" for warm-season crops. Within the zone:

• Zone 5a (Ottawa, Calgary): last frost May 15–20
• Zone 5b (London ON, Winnipeg): last frost May 10–15

Early May (cool-season push):

• Direct sow carrots, beets, peas, spinach, arugula, radishes
• Transplant broccoli, cabbage, cauliflower, kohlrabi starts
• Lettuce: thin to 20 cm for heading types, 10 cm for loose-leaf

After May 10–15 (post-frost):

• Transplant tomatoes, peppers, eggplant (hardened off) — see the full tomato transplanting guide for zone-by-zone timing
• Direct sow beans, zucchini, cucumber, corn, sunflowers
• Transplant squash starts (2–3 seeds per hill, 90 cm apart for summer squash)
• Peppers prefer soil above 18°C — use black plastic mulch in cooler microclimates

Succession sow: Lettuce, radishes, spinach every 2 weeks for continuous harvest.

For precise dates in this zone, see the Ontario planting dates guide.

Zone 6 — What to Plant in May (Toronto, Hamilton, Kelowna, Niagara)

Zone 6 gardeners are in prime planting mode through all of May. Last frost is typically April 15–May 1, so most of May is frost-free. Within the zone:

• Zone 6a (Kingston, Niagara): last frost May 1–10
• Zone 6b (Toronto, Hamilton, Metro Vancouver): last frost April 20–May 1

Early May:

• Transplant tomatoes, peppers, eggplant outdoors — transplant on a cloudy day or late afternoon to reduce transplant shock
• Direct sow beans, corn, squash, cucumbers (2–3 seeds per hill, 90–120 cm apart), melons (soil temp 15°C+)
• Plant basil outdoors after May 1, once night temperatures are reliably above 10°C
• Plant onion sets and transplants 2–3 cm deep, 10 cm apart

Through May:

• Succession sow beans, carrots, beets every 2–3 weeks
• Transplant sweet potato slips (soil temp 18°C+)
• Direct sow annual flowers: zinnias, sunflowers, nasturtiums

Zone 7–8 — What to Plant in May (BC Coast, Lower Mainland, Vancouver Island)

The BC coast and Lower Mainland are ahead of the rest of Canada. By May, warm-season crops are well underway and gardeners focus on succession planting and heat-lovers.

Zone 7 (Lower Mainland, Comox Valley):

• Transplant tomatoes, peppers into sheltered spots
• Direct sow beans, corn, squash, cucumbers
• Succession sow lettuce, cilantro, dill every 2 weeks

Zone 8 (Victoria, Saanich, Gulf Islands):

• Tomatoes and peppers should be in the ground by early May
• Direct sow melons (with row cover in cooler microclimates)
• Plant out basil, sweet potatoes

For BC-specific dates, see the British Columbia planting dates guide.

May Indoor Starts for Summer and Fall

While your outdoor garden fills up, keep starting these indoors for later transplanting:

• Late-season brassicas (broccoli, cabbage for fall harvest) — start indoors mid-May for August transplanting
• Celery — slow to germinate, start mid-May for July transplanting
• Leeks — start late May for fall harvest

May Planting Mistakes to Avoid

Transplanting tomatoes too early. Cold soil (below 12°C) stresses tomato roots even if air temperatures look fine. Wait for consistently warm nights. A week of delay saves weeks of recovery time.

Skipping hardening off. Seedlings moved directly from indoors to outdoors are shocked by UV, wind, and temperature swings. Spend 7–10 days transitioning them: start with 1 hour of outdoor shade and work up to full sun.

Planting beans in cold soil. Bean seeds rot below 15°C soil temperature. If your soil is still cold, wait — germination will be faster and more reliable in another week.

Missing the cool-season succession window. Many gardeners stop seeding lettuce and spinach once May arrives. Keep sowing every 2 weeks until your zone's daytime highs consistently hit 25°C, then switch to heat-tolerant varieties.

What to Have Ready in May

• Frost cloth or row cover — keep on hand until June in zones 3–4 for late cold snaps
• Tomato cages and bean trellises — set these up at planting time, not after
• Soil thermometer — confirm soil temp before direct sowing warm-season crops
• Your personalized planting schedule — use the free calculator at MyGardenPlanner.ca

Plan Your May Garden at MyGardenPlanner.ca

The free garden planner at MyGardenPlanner.ca calculates personalized planting and transplant dates based on your exact Canadian location. Enter your city and get a complete schedule for every crop you want to grow this season. No zone lookup required — just your city.

May is brief. Get your timing right and your season will reward you all the way through October.