When to Plant Tomatoes in Toronto
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GardenSays
Start tomato seeds indoors Mar 22 – Apr 5; transplant once frost danger is past and soil has warmed to ~60°F — typically May 17 – May 24 here.
- Start seeds indoors
- Mar 22 – Apr 5
- Transplant outside
- May 17 – May 24
- Last frost (typ.)
- May 10
In Toronto, ON, the typical last frost lands around May 10. Working back 6-8 weeks from transplant time gives you a seed-starting window of Mar 22 – Apr 5 indoors. Tomatoes are frost-tender, so wait for two conditions — frost danger past AND soil around 60°F — which here typically means May 17-May 24.
- This year's transplant window (May 17 – May 24) has passed — dates shown are for planning next season.
Do this this week
- 1.Passed for this season — plan next spring: start seeds indoors ~Mar 22 – Apr 5, transplant ~May 17 – May 24
Calculated result · 3 verified sources · Checked 2026-07-15 · How we decide
Why
That leaves roughly 139 days of growing season before the typical first fall frost (Oct 10) — enough for most varieties. In a short-season area, favor early-maturing varieties (check the days-to-maturity on the tag).
- Frost kills tender seedlings outright, and cold soil stunts them even without frost — both dates matter.
- The 50% frost date is a planning midpoint: a late frost is still possible, so keep covers handy for the first two weeks.
When this doesn't apply
- Season extenders (row covers, walls of water, cold frames) let you plant 2-3 weeks earlier than these windows.
- Frost dates are area averages — low spots and valley floors run colder than the local average.
How this was calculated
- 1. Last spring frostMay 10Source guidance
Toronto, ON: typical (50% probability) last 32°F frost
- 2. Seed starting windowMar 22 – Apr 5Calculated result
Tomato: start indoors 6-8 weeks before your typical transplant date
- 3. Transplant windowMay 17 – May 24Calculated result
Tomato is frost-tender: go out 7-14 days after the last frost, once soil reaches 60°F
- 4. First fall frostOct 10Source guidance
Toronto, ON: typical first 32°F frost in fall — the season's endpoint
Data sources
- University of Minnesota Extension — Growing tomatoes in home gardens — Start tomato seeds indoors about 6 weeks before the last frost; transplant after all danger of frost, once soil has warmed. (checked 2026-07-15)
- NOAA NCEI — 1991-2020 U.S. Climate Normals (freeze date probabilities) (checked 2026-07-15)
- National Gardening Association — frost date lookup (checked 2026-07-15)
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People also ask
What is the last frost date in Toronto?
Start tomato seeds indoors Mar 22 – Apr 5; transplant once frost danger is past and soil has warmed to ~60°F — typically May 17 – May 24 here. Calculate yours →
When should I start tomato seeds indoors?
Start tomato seeds indoors Mar 22 – Apr 5; transplant once frost danger is past and soil has warmed to ~60°F — typically May 17 – May 24 here. Calculate yours →
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