Why these dates work in zone 4a
Zone 4a's last spring frost averages May 20 and first fall frost Sep 20 — about 123 frost-free days. Lemon Balm 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 6 weeks ahead gives strong transplants ready the moment the soil warms.
Common questions
How long does lemon balm take to grow in zone 4a?
Lemon Balm matures in about 60–90 days from transplanting. In zone 4a that means setting plants out around May 20 and first picking around Jul 19.
Will lemon balm survive frost in zone 4a?
Yes — lemon balm tolerates light frost. In zone 4a you can set plants out a little before the last frost (around May 20) and keep harvesting past the first fall frost (around Sep 20).
For soil, spacing, pests and companion planting, see the full lemon balm growing guide →
