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- Start indoors
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- Fall crop
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Historical frost averages plus extension guidance, not a forecast. Check the forecast and soil temperature before planting.
Sow winter squash outdoors 2–4 weeks after your last spring frost, once the soil is at least 60°F. You can also start seeds indoors 1–2 weeks before the last frost and plant them out 2–4 weeks after it. Winter squash needs about 70–100 frost-free days to ripen, so check your season length above.
- Frost tolerance
- Very tender: no frost
- Soil temperature
- 60°F minimum; best 70–90°F
- Days to harvest
- 70–100 days from seed
The rule we use
- Start seeds indoors: 1–2 weeks before the last spring frost
- Sow outdoors: 2–4 weeks after the last spring frost
- Plant out: 2–4 weeks after the last spring frost
Planting winter squash
Butternut, acorn, spaghetti and other winter squash are very tender. Cold soil rots the seed and cold nights stall the plants, so wait until a couple of weeks after your last frost. Sow 2–3 seeds about 1 inch deep in each hill and thin to the best one or two plants. Vining types need 6 feet or more to roam; bush types fit smaller beds.
If your season is short, start seeds indoors in individual pots shortly before your last frost. Squash roots don't like being disturbed, so plant them out young, 2–3 weeks after sowing.
Watch the season length
Unlike zucchini, winter squash is harvested fully ripe, and that takes time. Add your variety's days to maturity to your planting date and make sure that's before your first fall frost, with a week or two to spare. If it's tight, choose a smaller, faster variety such as an acorn or a small butternut.
Harvest and curing
Squash is ripe when the skin is hard enough that a thumbnail doesn't dent it and the stem has turned dry and corky. Bring it in before a hard frost; a light frost on the vines is fine, but frost on the fruit shortens storage life.
Cut fruit with a few inches of stem, then cure it somewhere warm (about 80–85°F) for 1–2 weeks. Acorn squash doesn't need curing. Cured squash keeps for months in a cool, dry room.
Seeds and supplies for winter squash
- Winter squash seeds at True Leaf Market
- Park Seed for seeds and young plants.
- A soil thermometer to check the soil is warm enough before sowing.
- Frost cloth to cover plants if a late cold night is forecast.
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Questions about planting winter squash
When is it too late to plant winter squash?
Count back from your first fall frost by your variety's days to maturity, plus about two weeks. If today is past that date, choose a faster variety or grow summer squash instead.
Can I plant squash before the last frost?
No. Squash is killed by frost and grows poorly in cold soil. Wait 2–4 weeks after your last frost date, when the soil is at least 60°F.
How do I know when winter squash is ready?
The skin should be hard and resist a thumbnail, the color should be deep and even, and the stem should be dry and corky. Harvest before a hard freeze.
What's the difference between winter and summer squash?
Summer squash like zucchini is eaten young, about 50 days from sowing. Winter squash is left to ripen fully and store, which takes 70–100 days or more.
Sources
- Vegetable Planting Calendar for Central Maryland (2026), University of Maryland Extension
- Vegetables for Spring and Fall Planting; Vegetables for Summer Planting, University of Maryland Extension Master Gardeners
- Suggested Vegetable Planting Dates for Utah, Utah State University Extension
- Vegetable Planting Guide (CMG GardenNotes #720), Colorado State University Extension
- Frost dates: NOAA NCEI U.S. Climate Normals 1991–2020 (doi:10.25921/4ek7-fk11)