Cauliflower in Zone 5a & 5b
Brassica oleracea
When to plant cauliflower in zone 5b
Zones 5a and 5b share the same average frost dates in our data, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. Cauliflower needs a head start most zones can't give it by direct-sowing alone.
| Start indoors | Mar 29–Apr 5 |
|---|---|
| Direct sow / transplant outside | Apr 26–May 3 |
| Estimated harvest | Jul 5–Jul 12 (~70 days after transplanting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 1.5-2 ft.
Cauliflower has a reputation as the difficult brassica, and it's mostly earned: unlike broccoli or cabbage, it doesn't tolerate a check in growth well, and any stress (heat, drought, a root disturbance during transplanting) tends to show up later as a small, loose, or oddly colored head instead of the tight white curd you're after.
How cauliflower fits zone 5's season
Zone 5b's frost-free window runs about 148 days, from May 10 to October 5. Cauliflower needs about 70 days from transplant to first harvest.
Good companions
- Onion: Onion scent is reputed to confuse cabbage moths that target brassicas. The research behind this is real but garlic-specific (field trials intercropping garlic with cabbage reduced diamondback moth damage) — onion hasn't been tested the same way, so treat the onion version as a reasonable extrapolation, not a directly measured result.
Where to buy cauliflower seeds
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing cauliflower" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 5b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →
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Growing Cauliflower in USDA zone 5b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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