When to plant marigold 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

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Start indoors Apr 3 · Sow May 15 · First harvest Jun 29 · Wrap by Sep 18

Last spring frostMay 15

Start seeds indoorsApr 3

Direct sowMay 15

First harvestJun 29

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. Marigold is frost-sensitive, so the around last frost timing builds in a safety margin against a late cold snap — setting plants out too early risks losing them to frost. Starting seeds indoors 6 weeks ahead gives strong transplants ready the moment the soil warms.

Common questions

How long does marigold take to grow in zone 4b?

Marigold matures in about 45–55 days from sowing. In zone 4b that means sowing around May 15 and first picking around Jun 29.

Will marigold survive frost in zone 4b?

No — marigold 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 marigold growing guide →