Why these dates work in zone 3a
Zone 3a's last spring frost averages May 30 and first fall frost Sep 10 — about 103 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. One caveat: we haven't yet checked zone 3a against the weather archive, so those frost dates are an inherited estimate rather than a measurement. Give Garzed your location and it works from that location's own ten-year record instead.
Common questions
How long does nasturtium take to grow in zone 3a?
Nasturtium matures in about 50–70 days from sowing. In zone 3a that means sowing around Jun 6 and first picking around Jul 26.
Will nasturtium survive frost in zone 3a?
No — nasturtium is frost-sensitive. In zone 3a, wait until after the last frost (around May 30) to plant, and harvest before the first fall frost (around Sep 10).
For soil, spacing, pests and companion planting, see the full nasturtium growing guide →