When to plant onion in zone 6a — planting calendar

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Showing USDA Zone 6A

Growing SeasonZone 6a

Last frost ~Apr 30First frost ~Oct 10Today

Start indoorsTransplant / sowHarvestFrost risk

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Start indoors Feb 19 · Sow Apr 16 · First harvest Jul 15 · Wrap by Aug 12

Last spring frostApr 30

Start seeds indoorsFeb 19

Direct sowApr 16

First harvestJul 15

Last harvestAug 12

First fall frostOct 10

Why these dates work in zone 6a

Zone 6a's last spring frost averages Apr 30 and first fall frost Oct 10 — about 163 frost-free days. Onion tolerates light frost, so you can sow ahead of the last-frost date and keep harvesting into the cooler fall. Starting seeds indoors 10 weeks ahead gives strong transplants ready the moment the soil warms.

Common questions

How long does onion take to grow in zone 6a?

Onion matures in about 90–110 days from sowing. In zone 6a that means sowing around Apr 16 and first picking around Jul 15.

Will onion survive frost in zone 6a?

Yes — onion tolerates light frost. In zone 6a you can sow a little before the last frost (around Apr 30) and keep harvesting past the first fall frost (around Oct 10).

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