When Should You Plant Summer Squash?
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GardenSays
Start summer squash seeds indoors Apr 14 – Apr 28; transplant once frost danger is past and soil has warmed to ~65°F — typically May 12 – May 19 here.
- Start seeds indoors
- Apr 14 – Apr 28
- Transplant outside
- May 12 – May 19
- Last frost (typ.)
- May 5
In Minneapolis, MN, the typical last frost lands around May 5. Working back 2-4 weeks from transplant time gives you a seed-starting window of Apr 14 – Apr 28 indoors. Summer squash plants are very frost-tender, so wait for two conditions — frost danger past AND soil around 65°F — which here typically means May 12-May 19.
- Summer squash isn't a direct-sow crop in frost climates — showing the indoor-start plan instead.
- This year's transplant window (May 12 – May 19) has passed — dates shown are for planning next season.
Do this this week
- 1.Passed for this season — plan next spring: start seeds indoors ~Apr 14 – Apr 28, transplant ~May 12 – May 19
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 5) — 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
- Same UMN guide covers summer squash and zucchini together — same warm-soil requirement.
- 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 5Source guidance
Minneapolis, MN: typical (50% probability) last 32°F frost
- 2. Seed starting windowApr 14 – Apr 28Calculated result
Summer squash: start indoors 2-4 weeks before your typical transplant date
- 3. Transplant windowMay 12 – May 19Calculated result
Summer squash is very frost-tender: go out 7-14 days after the last frost, once soil reaches 65°F
- 4. First fall frostOct 5Source guidance
Minneapolis, MN: typical first 32°F frost in fall — the season's endpoint
Data sources
- University of Minnesota Extension — Growing summer squash and zucchini in home gardens — Sow seed directly in the garden after the soil has warmed (late May to early June in Minnesota); plastic mulch and row covers allow earlier planting. (checked 2026-07-18)
- 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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