When to plant bok choy 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

APRMAYJUNJUL

Start indoors Apr 17 · Transplant Apr 24 · First harvest Jun 8 · Wrap by Jun 29

Last spring frostMay 15

Start seeds indoorsApr 17

Transplant outApr 24

First harvestJun 8

Last harvestJun 29

Fall succession sowJul 31

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. Bok Choy 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 4 weeks ahead gives strong transplants ready the moment the soil warms. There's also room for a fall succession sowing around Jul 31 for a second harvest before frost.

Common questions

How long does bok choy take to grow in zone 4b?

Bok Choy matures in about 45–60 days from transplanting. In zone 4b that means setting plants out around Apr 24 and first picking around Jun 8.

Will bok choy survive frost in zone 4b?

Yes — bok choy 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 bok choy in zone 4b?

Yes — in zone 4b there's time for a fall sowing around Jul 31 for a second harvest before frost.

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