When to plant sunflower in zone 5b — planting calendar

Not your zone?

Showing USDA Zone 5B

Growing SeasonZone 5b

Last frost ~May 15First frost ~Sep 30Today

Start indoorsTransplant / sowHarvestFrost risk

MAYJUNJULAUG

Sow May 15 · First harvest Jul 14 · Wrap by Aug 11

Last spring frostMay 15

Direct sowMay 15

First harvestJul 14

Last harvestAug 11

First fall frostSep 30

Why these dates work in zone 5b

Zone 5b's last spring frost averages May 15 and first fall frost Sep 30 — about 138 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 5b?

Sunflower matures in about 60–100 days from sowing. In zone 5b that means sowing around May 15 and first picking around Jul 14.

Will sunflower survive frost in zone 5b?

No — sunflower is frost-sensitive. In zone 5b, wait until after the last frost (around May 15) to plant, and harvest before the first fall frost (around Sep 30).

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