Growing Sweet Peas in Canada — Sow Dates by Region
A genuine timing exception — sow weeks before last frost, not after, and expect blooms to stop once real summer heat arrives. Sow dates by region, plus the coastal BC fall-sowing trick.
Sweet peas invert the usual annual-flower rule. Where zinnias and marigolds wait for warm soil after frost has fully passed, sweet peas actually prefer cool soil and go in weeks before your last frost date.
The trade-off is a shorter bloom window: sweet peas largely shut down once real summer heat arrives, so the Canadian growing story is a strong late-spring-to-early-summer show rather than season-long flowers.
Sweet peas in Canada at a glance: Sow 3–6 weeks before last frost, as soon as soil can be worked. Vancouver: Feb–early March. Toronto/Windsor: mid-to-late March. Ottawa/Montreal/Prairies: April. Coastal BC can fall-sow (Oct–Nov) for earlier spring blooms. Blooms stop once summer heat hits — provide a trellis from the start.
When should you plant sweet peas where you garden?
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| Region (City) | Zone | Last Frost | Spring Sow | Fall Sow Option |
|---|---|---|---|---|
| Coastal BC (Vancouver) | 8a | Mar 15 | Feb–early Mar | Yes — Oct–Nov for earlier blooms |
| BC Interior (Kelowna) | 6b | May 5 | Late Mar–Apr | No — winter too harsh |
| Southern Ontario (Toronto) | 6b | Apr 20 | Mid-late Mar | No — winter too harsh |
| SW Ontario (Windsor) | 7a | Apr 20 | Mid-Mar | No — winter too harsh |
| Eastern Ontario (Ottawa) | 5a | May 9 | Early-mid Apr | No — winter too harsh |
| Quebec (Montreal) | 5b | May 9 | Early-mid Apr | No — winter too harsh |
| Prairies (Calgary/Edmonton/Winnipeg) | 3a–4a | May 14–23 | Mid-late Apr | No — winter far too harsh |
| Maritimes (Halifax) | 6a | May 10 | Late Mar–early Apr | No — winter too harsh |
Common Sweet Pea Problems in Canada
Blooms stopping suddenly in summer
The plant's normal response to consistent heat above the mid-20s°C, not a growing failure. Plan around a strong spring/early-summer bloom window rather than expecting flowers all season.
Sprawling, poor-flowering vines
Almost always a missing or too-late trellis. Install support at sowing time so tendrils can grip from the start.
Slow, patchy germination
Sweet pea's hard seed coat can slow sprouting, especially in cool soil. Soaking seed 12–24 hours before sowing softens the coat and speeds germination.
Frequently Asked Questions
When should I plant sweet peas in Canada?
3–6 weeks before last frost — earlier than most flowers. Vancouver: Feb–early March. Toronto/Windsor: mid-to-late March.
Can I fall-sow sweet peas?
Only reliably in coastal BC — elsewhere in Canada winter kills fall-sown seedlings.
Why did my sweet peas stop blooming?
Summer heat — sweet peas are a cool-season crop and shut down once temperatures push into the high 20s°C.