When to plant tomato 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 · Transplant May 29 · First harvest Jul 28 · Wrap by Sep 18

Last spring frostMay 15

Start seeds indoorsApr 3

Transplant outMay 29

First harvestJul 28

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. Tomato 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 6 weeks ahead gives strong transplants ready the moment the soil warms.

Common questions

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

Tomato matures in about 60–85 days from transplanting. In zone 4b that means setting plants out around May 29 and first picking around Jul 28.

Will tomato survive frost in zone 4b?

No — tomato 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 tomato growing guide →