When to Plant Zucchini and Summer Squash

Zucchini and summer squash are a tender warm-season vegetable. Frost damages them, so they go out only after the last spring frost.

Start seeds indoors 1 to 3 weeks before the last spring frost, and plant out 1 to 3 weeks after the last frost. Or sow them where they will grow, 1 to 3 weeks after the last spring frost. For a fall crop, sow 10 to 13 weeks before the first fall frost. The first harvest comes about 45 to 60 days after sowing.

Example dates

The same rules in dates for three climates, using typical frost dates. Enter your ZIP code above for the dates where you live.

Zucchini and Summer Squash: dates by last spring and first fall frost
TaskLast frost Mar 15first Nov 15Last frost Apr 15first Oct 25Last frost May 15first Sep 30
Start seeds indoorsFeb 22 – Mar 8Mar 25 – Apr 8Apr 24 – May 8
Harden offMar 15 – 21Apr 15 – 21May 15 – 21
Plant outMar 22 – Apr 5Apr 22 – May 6May 22 – Jun 5
HarvestApr 8 – May 6May 9 – Jun 6Jun 8 – Jul 6
Direct-sown: Sow outdoorsMar 22 – Apr 5Apr 22 – May 6May 22 – Jun 5
Direct-sown: HarvestMay 6 – Jun 3Jun 6 – Jul 4Jul 6 – Aug 3
Fall: Sow outdoorsAug 16 – Sep 6Jul 26 – Aug 16Jul 1 – 22
Fall: HarvestSep 30 – Oct 28Sep 9 – Oct 7Aug 15 – Sep 12

Growing zucchini and summer squash

Check plants daily once they bloom, since fruit grows from tender to oversized in a few days.

Plan your beds with these dates

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Questions

When do I start zucchini and summer squash indoors?

1 to 3 weeks before the last spring frost: with a last frost of April 15, that's Mar 25 – Apr 8. Enter your ZIP code above for your own dates.

Can zucchini and summer squash go in before the last frost?

No. Zucchini and summer squash are damaged by frost: plant them out 1 to 3 weeks after the last spring frost.

How long do zucchini and summer squash take to grow?

About 45 to 60 days from sowing to the first harvest, which then lasts about 4 weeks. Varieties differ: check the seed packet.

Can I grow zucchini and summer squash in fall?

Yes. Sow 10 to 13 weeks before the first fall frost. Enter your ZIP code above for the dates where you live.

How often should I sow zucchini and summer squash?

Every 21 days or so for a steady harvest, until the last sowing that still ripens before your first fall frost. The planner works that date out for your ZIP code.

More planting dates

Sources

  1. NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020 (annual/seasonal, by station: freeze dates at 32 °F)
  2. Colorado State University Extension: Vegetable Planting Guide (CMG GardenNotes #720)
  3. Virginia Cooperative Extension, Virginia Tech: Virginia's Home Garden Vegetable Planting Guide: Recommended Planting Dates and Amounts to Plant (426-331 / SPES-673P, 2025)
  4. University of Maryland Extension: Vegetable Planting Calendar for central Maryland
  5. UNH Cooperative Extension: Growing Vegetables: When to Plant your Vegetable Garden (2016)
  6. NC State Extension: Extension Gardener Handbook, Chapter 16: Vegetable Gardening
  7. WSU Extension: Pacific Northwest Gardener's Handbook, Chapter 7: Vegetable Gardening
  8. Iowa State: Fall Planting of Vegetables
  9. Iowa State: Germination Requirements for Annuals and Vegetables
  10. Iowa State: Growing Squash in Iowa
  11. Utah State University Extension: Suggested Vegetable Planting Dates for Utah
  12. Montana State University Extension: Can I Grow That Here? Vegetable Seed and Transplant Schedules (MontGuide MT199308AG, rev. 2018)
  13. Clemson Cooperative Extension HGIC: Small-Scale Gardening (square-foot planting guide)
  14. UC Master Gardener Program, UC ANR: Companion Planting Chart: Companion Planting for Edible Crops
  15. University of Wisconsin–Madison Extension, Kenosha County: Companion Plants for the Vegetable Garden (column, 2012)
  16. Utah State University Extension, Utah 4-H: Creating Sustainable School and Home Gardens: Companion Planting (2025)
  17. University of Arizona Cooperative Extension, Yavapai County: The Art of Companion Planting (Master Gardener presentation, 2023)
  18. N.C. A&T State University Cooperative Extension: Five Veggies You Can Grow at Home