Winter Squash in Zone 3a & 3b

Cucurbita maxima

When to plant winter squash in zone 3b

Zones 3a and 3b share the same average frost dates in our data, so this page covers both.

Method: Direct sow: Direct-sow outside. Winter Squash doesn't transplant well, or doesn't need the extra time indoors.

Spacing: about 4 square feet per plant (square-foot-gardening spacing). Mature height: 1-1.5 ft.

Winter squash is a long game: direct-seeded after your last frost, it takes around 100 days to mature, the longest of the common squash-family crops, and unlike a zucchini, it's harvested once, cured, and stored for months rather than picked continuously all summer.

How winter squash fits zone 3's season

Zone 3b's frost-free window runs about 98 days, from May 30 to September 5. Winter Squash needs about 100 days from sowing to first harvest.

Good companions

• Sweet Corn: The classic 'three sisters' pairing. WSU Extension confirms the real mechanism: squash's broad leaves shade the soil, reducing evaporation and inhibiting weed seed germination, while corn stalks give beans (the third sister) something to climb.

Where to buy winter squash seeds

• Botanical Interests
• True Leaf Market
• Burpee
• High Mowing Organic Seeds

See why we recommend these suppliers →

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See it growing

Search YouTube for "growing winter squash" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)

← Back to the full zone 3b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →

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Growing Winter Squash in USDA zone 3b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.

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