When to plant marigold in zone 3b — planting calendar

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Showing USDA Zone 3B

Growing SeasonZone 3b

Last frost ~May 25First frost ~Sep 15Today

Start indoorsTransplant / sowHarvestFrost risk

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Start indoors Apr 13 · Sow May 25 · First harvest Jul 9 · Wrap by Sep 8

Last spring frostMay 25

Start seeds indoorsApr 13

Direct sowMay 25

First harvestJul 9

Last harvestSep 8

First fall frostSep 15

Why these dates work in zone 3b

Zone 3b's last spring frost averages May 25 and first fall frost Sep 15 — about 113 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 3b?

Marigold matures in about 45–55 days from sowing. In zone 3b that means sowing around May 25 and first picking around Jul 9.

Will marigold survive frost in zone 3b?

No — marigold is frost-sensitive. In zone 3b, wait until after the last frost (around May 25) to plant, and harvest before the first fall frost (around Sep 15).

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