Cauliflower in Zone 5a & 5b
Brassica oleracea
Yes, cauliflower grows in zones 5a and 5b. Start seeds indoors Mar 29–Apr 5 and plant out Apr 26–May 3. For a fall crop, start seeds indoors Jun 15–Jun 29 and plant out Jul 13–Jul 27.
When to plant cauliflower in zone 5b
Zones 5a and 5b share the same average frost dates, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. It needs a head start most zones can't give it by direct-sowing alone.
| Window | Spring window |
|---|---|
| Start indoors | Mar 29–Apr 5 |
| Direct sow / transplant outside | Apr 26–May 3 |
| Estimated harvest | Jul 5–Jul 12 (~70 days after transplanting) |
| Window | Fall window |
|---|---|
| Start indoors | Jun 15–Jun 29 |
| Direct sow / transplant outside | Jul 13–Jul 27 |
| Estimated harvest | Sep 21–Oct 5 (~70 days after transplanting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 1.5-2 ft.
Fall window: the last sowing date is the average first frost minus days to maturity, the method in Purdue Extension's fall garden guide, which lists cauliflower for late-summer planting.
Plant alongside it in zone 5b
These go outside within two weeks of cauliflower in zone 5b, so one planting day can cover them.
- RadishApr 12–Apr 19
- CarrotApr 19–Apr 26
- CabbageApr 26–May 3
- LettuceApr 26–May 3
- BroccoliApr 26–May 3
- Flower SproutsApr 26–May 3
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.
Cauliflower planting windows in every zone
Zone 5b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Harvest |
|---|---|---|---|
| 2a & 2b | Apr 8–Apr 15 | May 6–May 13 | Jul 15–Jul 22 |
| 3a & 3b | Apr 18–Apr 25 | May 16–May 23 | Jul 25–Aug 1 |
| 4a & 4b | Apr 3–Apr 10 | May 1–May 8 | Jul 10–Jul 17 |
| 5a & 5bSpring window (your zone) | Mar 29–Apr 5 | Apr 26–May 3 | Jul 5–Jul 12 |
| Fall window | Jun 15–Jun 29 | Jul 13–Jul 27 | Sep 21–Oct 5 |
| 6a & 6bSpring window | Mar 14–Mar 21 | Apr 11–Apr 18 | Jun 20–Jun 27 |
| Fall window | Jun 25–Jul 9 | Jul 23–Aug 6 | Oct 1–Oct 15 |
| 7a & 7bSpring window | Feb 27–Mar 6 | Mar 27–Apr 3 | Jun 5–Jun 12 |
| Fall window | Jul 5–Jul 19 | Aug 2–Aug 16 | Oct 11–Oct 25 |
| 8a & 8bSpring window | Feb 11–Feb 18 | Mar 11–Mar 18 | May 20–May 27 |
| Fall window | Jul 21–Aug 4 | Aug 18–Sep 1 | Oct 27–Nov 10 |
| 9a & 9bSpring window | Jan 4–Jan 11 | Feb 1–Feb 8 | Apr 12–Apr 19 |
| Fall window | Aug 15–Aug 29 | Sep 12–Sep 26 | Nov 21–Dec 5 |
| 10a & 10bFall window | Aug–Dec | Sep–Jan | ~70 days after transplanting |
Harvest dates are about 70 days after the sow or plant-out date, not after starting seeds indoors.
Zone 2 sows before zone 3 here, which looks wrong and is not. USDA zones rank winter cold, not season length, and zone 2 is mostly interior Alaska, where hard winters come with warm summers. More on what a zone measures.
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
Botanical Interests · Burpee · High Mowing Organic Seeds (each supplier's cauliflower seeds)
Varieties we recommend, and where to get them:
- Violet Queen: Ohioline's purple option, listed among their midseason varieties. Buy: True Leaf Market Full notes
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 · 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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