Zone 7a covers 30 days of last-frost dates. We measured Fayetteville, AR at Mar 31 and Ogden, UT at Apr 30. Give us your town or ZIP and we'll use ten years of daily lows recorded at your own coordinates instead of the middle of that range.
Why these dates work in zone 7a
Zone 7a's last spring frost averages Apr 13 and first fall frost Nov 12 — about 213 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 7a?
Onion matures in about 90–110 days from sowing. In zone 7a that means sowing around Mar 30 and first picking around Jun 28.
Will onion survive frost in zone 7a?
Yes — onion tolerates light frost. In zone 7a you can sow a little before the last frost (around Apr 13) and keep harvesting past the first fall frost (around Nov 12).
For soil, spacing, pests and companion planting, see the full onion growing guide →