When to Plant Squash in Canada — Sow Dates by Region
Direct sow after last frost once soil is warm — but the real question for winter squash isn't just "is it past frost," it's "is there enough season left." Sow dates by region, and how to check before it's too late.
Squash is a warm-season crop with a simple rule at the start of the season — wait for frost to fully pass and the soil to warm — but a more interesting question at the other end. Winter squash varieties (butternut, acorn, spaghetti) take 80–110 days to mature, which in some Canadian regions is close to the entire frost-free window.
That's the real decision this guide is built around: not just when you can plant squash, but whether there's actually enough season left to bring it to harvest.
Squash in Canada at a glance: Direct sow after last frost once soil reaches 18°C. Toronto/Windsor: late May–early June. Vancouver: mid-to-late May. Ottawa/Montreal/Calgary/Edmonton/Winnipeg: early-to-mid June. Winter squash needs 80–110 days — count back from your first fall frost before sowing a long-season variety in a short-season region.
When should you plant squash where you garden?
Get your city's frost dates, indoor seed-starting dates, and this week's planting jobs — three free tools.
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🥦 Shop vegetable seeds at West Coast Seeds →Squash Sow Dates Across Canada
| Region (City) | Zone | Last Frost | Sow Date | First Fall Frost | Season for Squash |
|---|---|---|---|---|---|
| Coastal BC (Vancouver) | 8a | Mar 15 | May 15–25 | Nov 15 | Long — any variety |
| BC Interior (Kelowna) | 6b | May 5 | May 25–Jun 5 | Oct 5 | Long — any variety |
| Southern Ontario (Toronto) | 6b | Apr 20 | May 25–Jun 5 | Oct 15 | Long — any variety |
| SW Ontario (Windsor) | 7a | Apr 20 | May 15–25 | Oct 25 | Long — any variety |
| Eastern Ontario (Ottawa) | 5a | May 9 | Jun 1–10 | Oct 5 | Moderate — check days-to-maturity |
| Quebec (Montreal) | 5b | May 9 | Jun 1–10 | Oct 5 | Moderate — check days-to-maturity |
| Prairies (Calgary) | 3b | May 23 | Jun 5–15 | Sep 15 | Short — fast varieties only (80–90 days) |
| Prairies (Edmonton) | 4a | May 14 | Jun 1–10 | Sep 20 | Short — fast varieties only (80–90 days) |
| Prairies (Winnipeg) | 3a | May 19 | Jun 5–10 | Sep 22 | Short — fast varieties only (80–90 days) |
| Maritimes (Halifax) | 6a | May 10 | May 25–Jun 5 | Oct 15 | Long — any variety |
Common Squash Problems in Canada
Squash vine borer
Sudden wilting of an otherwise healthy plant, from moth larvae tunnelling into the stem base. Row cover until flowering, check stems for sawdust-like frass, and bury a few vine nodes as insurance rooting points.
Unripe fruit caught by fall frost
The core risk in shorter-season regions. Choose a variety whose days-to-maturity clearly fits your region's season, and sow as early as soil temperature allows rather than delaying.
Poor fruit set / no squash forming
Squash has separate male and female flowers and needs pollinator activity to set fruit. Early-season flowers are often mostly male; fruit set typically improves once both flower types appear together. Avoid insecticide spraying during flowering to protect pollinators.
Frequently Asked Questions
When should I plant squash in Canada?
Direct sow after last frost once soil hits 18°C. Toronto/Windsor: late May–early June. Prairies: early-to-mid June.
Is it too late to plant squash?
Depends on the variety. Count back from your first fall frost — winter squash needs 80–110 days; if that doesn't fit, it's too late for this season.
Should I start squash indoors?
Direct sow is standard. A brief indoor head start can help in short-season regions but isn't necessary elsewhere.