Pumpkin in Zone 4a & 4b
Cucurbita pepo
When to plant pumpkin in zone 4b
Zones 4a and 4b share the same average frost dates in our data, so this page covers both.
Method: Direct sow: Direct-sow outside. Pumpkin doesn't transplant well, or doesn't need the extra time indoors.
| Start indoors | Not typically started indoors |
|---|---|
| Direct sow / transplant outside | May 22–May 29 |
| Estimated harvest | Sep 9–Sep 16 (~110 days after direct-sowing) |
Spacing: about 10 square feet per plant (square-foot-gardening spacing). Mature height: 1-1.5 ft.
Pumpkins ask for more room and more patience than almost anything else in the garden: around 110 days from seed to harvest, and vines that sprawl far enough that planning calls for a mere tenth of a plant per square foot, in practice, that means giving one plant several square feet to itself.
How pumpkin fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Pumpkin needs about 110 days from sowing to first harvest.
Good companions
- Sweet Corn: The same 'three sisters' mechanism as winter squash: WSU Extension confirms pumpkin's broad leaves shade the soil, suppressing weeds and reducing evaporation around corn.
Where to buy pumpkin seeds
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing pumpkin" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 4b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →
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Growing Pumpkin in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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