When to plant onion in zone 8a — planting calendar

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Showing USDA Zone 8A

Growing SeasonZone 8a

Last frost ~Mar 25First frost ~Nov 10Today

Start indoorsTransplant / sowHarvestFrost risk

JANFEBMARAPRMAYJUNJUL

Start indoors Jan 14 · Sow Mar 11 · First harvest Jun 9 · Wrap by Jul 7

Last spring frostMar 25

Start seeds indoorsJan 14

Direct sowMar 11

First harvestJun 9

Last harvestJul 7

First fall frostNov 10

Why these dates work in zone 8a

Zone 8a's last spring frost averages Mar 25 and first fall frost Nov 10 — about 230 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 8a?

Onion matures in about 90–110 days from sowing. In zone 8a that means sowing around Mar 11 and first picking around Jun 9.

Will onion survive frost in zone 8a?

Yes — onion tolerates light frost. In zone 8a you can sow a little before the last frost (around Mar 25) and keep harvesting past the first fall frost (around Nov 10).

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