Zone 5b covers 25 days of last-frost dates. We measured Davenport, IA at Apr 16 and Idaho Falls, ID at May 11. 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 5b
Zone 5b's last spring frost averages Apr 28 and first fall frost Oct 22 — about 177 frost-free days. Radish tolerates light frost, so you can sow ahead of the last-frost date and keep harvesting into the cooler fall. There's also room for a fall succession sowing around Sep 10 for a second harvest before frost.
Common questions
How long does radish take to grow in zone 5b?
Radish matures in about 22–30 days from sowing. In zone 5b that means sowing around Mar 31 and first picking around Apr 22.
Will radish survive frost in zone 5b?
Yes — radish tolerates light frost. In zone 5b you can sow a little before the last frost (around Apr 28) and keep harvesting past the first fall frost (around Oct 22).
Can I plant a second crop of radish in zone 5b?
Yes — in zone 5b there's time for a fall sowing around Sep 10 for a second harvest before frost.
For soil, spacing, pests and companion planting, see the full radish growing guide →