Zone 6b covers 17 days of last-frost dates. We measured Springfield, MO at Apr 6 and Detroit, MI at Apr 23. 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 6b
Zone 6b's last spring frost averages Apr 19 and first fall frost Nov 6 — about 201 frost-free days. Leek 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 12 weeks ahead gives strong transplants ready the moment the soil warms.
Common questions
How long does leek take to grow in zone 6b?
Leek matures in about 100–120 days from transplanting. In zone 6b that means setting plants out around Apr 5 and first picking around Jul 14.
Will leek survive frost in zone 6b?
Yes — leek tolerates light frost. In zone 6b you can set plants out a little before the last frost (around Apr 19) and keep harvesting past the first fall frost (around Nov 6).
For soil, spacing, pests and companion planting, see the full leek growing guide →