When to plant zucchini in zone 4b — planting calendar

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Showing USDA Zone 4B

Growing SeasonZone 4b

Last frost ~May 15First frost ~Sep 25Today

Start indoorsTransplant / sowHarvestFrost risk

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Start indoors Apr 24 · Sow May 22 · First harvest Jul 6 · Wrap by Sep 14

Last spring frostMay 15

Start seeds indoorsApr 24

Direct sowMay 22

First harvestJul 6

Last harvestSep 14

First fall frostSep 25

Why these dates work in zone 4b

Zone 4b's last spring frost averages May 15 and first fall frost Sep 25 — about 133 frost-free days. Zucchini is frost-sensitive, so the 1w after frost timing builds in a safety margin against a late cold snap — setting plants out too early risks losing them to frost. Starting seeds indoors 3 weeks ahead gives strong transplants ready the moment the soil warms.

Common questions

How long does zucchini take to grow in zone 4b?

Zucchini matures in about 45–60 days from sowing. In zone 4b that means sowing around May 22 and first picking around Jul 6.

Will zucchini survive frost in zone 4b?

No — zucchini is frost-sensitive. In zone 4b, wait until after the last frost (around May 15) to plant, and harvest before the first fall frost (around Sep 25).

For soil, spacing, pests and companion planting, see the full zucchini growing guide →