When to plant broccoli 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 Apr 24 · First harvest Jul 13 · Wrap by Aug 10

Last spring frostMay 15

Start seeds indoorsApr 3

Transplant outApr 24

First harvestJul 13

Last harvestAug 10

Fall succession sowJun 26

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. Broccoli tolerates light frost, so you can set plants out ahead of the last-frost date and keep harvesting into the cooler fall. Starting seeds indoors 6 weeks ahead gives strong transplants ready the moment the soil warms. There's also room for a fall succession sowing around Jun 26 for a second harvest before frost.

Common questions

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

Broccoli matures in about 80–100 days from transplanting. In zone 4b that means setting plants out around Apr 24 and first picking around Jul 13.

Will broccoli survive frost in zone 4b?

Yes — broccoli tolerates light frost. In zone 4b you can set plants out a little before the last frost (around May 15) and keep harvesting past the first fall frost (around Sep 25).

Can I plant a second crop of broccoli in zone 4b?

Yes — in zone 4b there's time for a fall sowing around Jun 26 for a second harvest before frost.

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