When to plant nasturtium in zone 4b — planting calendar

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Showing USDA Zone 4B

Growing SeasonZone 4b

Last frost ~May 15First frost ~Sep 25Today

Start indoorsTransplant / sowHarvestFrost risk

MAYJUNJULAUGSEP

Sow May 22 · First harvest Jul 11 · Wrap by Sep 18

Last spring frostMay 15

Direct sowMay 22

First harvestJul 11

Last harvestSep 18

First fall frostSep 25

Why these dates work in zone 4b

Zone 4b's last spring frost averages May 15 and first fall frost Sep 25 — about 133 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 4b?

Nasturtium matures in about 50–70 days from sowing. In zone 4b that means sowing around May 22 and first picking around Jul 11.

Will nasturtium survive frost in zone 4b?

No — nasturtium is frost-sensitive. In zone 4b, wait until after the last frost (around May 15) to plant, and harvest before the first fall frost (around Sep 25).

For soil, spacing, pests and companion planting, see the full nasturtium growing guide →