Last spring frostMay 6
Direct sowMay 13
First harvestJul 2
Last harvestSep 24
First fall frostOct 22
Why these dates work in zone 3b
Zone 3b's last spring frost averages May 6 and first fall frost Oct 22 — about 169 frost-free days. Nasturtium is frost-sensitive, so the 1w after frost timing builds in a safety margin against a late cold snap — setting plants out too early risks losing them to frost.
Common questions
How long does nasturtium take to grow in zone 3b?
Nasturtium matures in about 50–70 days from sowing. In zone 3b that means sowing around May 13 and first picking around Jul 2.
Will nasturtium survive frost in zone 3b?
No — nasturtium is frost-sensitive. In zone 3b, wait until after the last frost (around May 6) to plant, and harvest before the first fall frost (around Oct 22).
For soil, spacing, pests and companion planting, see the full nasturtium growing guide →