When to plant sunflower in zone 3a — planting calendar

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Showing USDA Zone 3A

Growing SeasonZone 3a

Last frost ~May 30First frost ~Sep 10Today

Start indoorsTransplant / sowHarvestFrost risk

MAYJUNJULAUGSEP

Sow May 30 · First harvest Jul 29 · Wrap by Aug 26

Last spring frostMay 30

Direct sowMay 30

First harvestJul 29

Last harvestAug 26

First fall frostSep 10

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. Sunflower 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.

Common questions

How long does sunflower take to grow in zone 3a?

Sunflower matures in about 60–100 days from sowing. In zone 3a that means sowing around May 30 and first picking around Jul 29.

Will sunflower survive frost in zone 3a?

No — sunflower 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 sunflower growing guide →