When to plant watermelon in zone 3b — planting calendar

Not your zone?

Showing USDA Zone 3B

Growing SeasonZone 3b

Last frost ~May 25First frost ~Sep 15Today

Start indoorsTransplant / sowHarvestFrost risk

APRMAYJUNJULAUGSEP

Start indoors Apr 27 · Transplant Jun 8 · First harvest Aug 17 · Wrap by Sep 7

Last spring frostMay 25

Start seeds indoorsApr 27

Transplant outJun 8

First harvestAug 17

Last harvestSep 7

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. Watermelon is frost-sensitive, so the 2w after 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 4 weeks ahead gives strong transplants ready the moment the soil warms.

Common questions

How long does watermelon take to grow in zone 3b?

Watermelon matures in about 70–90 days from transplanting. In zone 3b that means setting plants out around Jun 8 and first picking around Aug 17.

Will watermelon survive frost in zone 3b?

No — watermelon 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 watermelon growing guide →