Zone 5a covers 27 days of last-frost dates. We measured Sioux City, IA at Apr 20 and Bozeman, MT at May 17. 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 5a
Zone 5a's last spring frost averages Apr 30 and first fall frost Oct 20 — about 173 frost-free days. Oregano tolerates light frost, so you can set plants out ahead of the last-frost date and keep harvesting into the cooler fall. Starting seeds indoors 8 weeks ahead gives strong transplants ready the moment the soil warms.
Common questions
How long does oregano take to grow in zone 5a?
Oregano matures in about 60–80 days from transplanting. In zone 5a that means setting plants out around Apr 23 and first picking around Jun 22.
Will oregano survive frost in zone 5a?
Yes — oregano tolerates light frost. In zone 5a you can set plants out a little before the last frost (around Apr 30) and keep harvesting past the first fall frost (around Oct 20).
For soil, spacing, pests and companion planting, see the full oregano growing guide →