When to plant cauliflower in New Hampshire
New Hampshire’s average last spring frost is May 13, and the first fall frost typically arrives around September 25 — about 135 frost-free days (USDA zones 3b, 4a, 4b, 5a, 5b, 6a). Cauliflower needs 60–90 days to mature, which fits comfortably within New Hampshire's growing season.
When to plant cauliflower in New Hampshire: the short answer
For a spring planting, plant out Apr 22 – May 9, with seeds started indoors Mar 25 – Apr 8. Seeds germinate in soil from 45 to 85°F.
Windows are ~1–2 week bands around each date. Frost dates are a statewide average from NOAA/NCEI normals; your town may differ by two weeks or more. Calendar year 2026.
How to grow cauliflower in New Hampshire, step by step
- Start seeds indoors (Mar 25 – Apr 8). Sow seeds ½ inch deep in seed-starting mix under bright light. They take 5-10 days to sprout, fastest in soil around 75°F. Harden seedlings off for a week before they go outside.
- Prepare the bed. It needs at least six to eight hours of direct sun a day and loose soil at least 18 inches deep, with a pH between 6.0 and 7.5. Dig in compost before planting.
- Plant out (Apr 22 – May 9). Space plants about 18 inches apart in rows 30 inches apart. It tolerates a light frost but not a hard freeze. As a cool-season crop it does best before summer heat arrives in New Hampshire.
- Water and feed. It needs plenty of water; keep the soil evenly moist and never let it dry out.
- Watch for pests and problems. Pests: cabbage worm, cabbage looper, aphids, cabbage root maggot. Diseases and disorders: clubroot, black rot, downy mildew.
- Harvest (from about Jun 28 – Jul 28). Cauliflower takes 60-90 days to reach harvest. The fussiest brassica - any check from cold, heat, or drought ruins the head. Fall crops are far more reliable than spring. Blanch white types by tying leaves over the curd.
Figures come from our crop data; dates use New Hampshire’s average frost dates. More in the full cauliflower growing guide.
Cauliflower planting dates by USDA zone in New Hampshire
New Hampshire spans USDA zones 3b, 4a, 4b, 5a, 5b, 6a. Colder zones, usually higher or further inland, have a later last spring frost and an earlier first fall frost than the state average, so the cauliflower dates shift with them.
When to plant cauliflower in nearby states
| State | Last frost | Plant out |
|---|---|---|
| New Hampshire (this page) | May 13 | Apr 22 – May 9 |
| Maine | May 14 | Apr 23 – May 10 |
| Vermont | May 14 | Apr 23 – May 10 |
| Massachusetts | April 24 | Apr 3 – Apr 20 |
| Rhode Island | April 25 | Apr 4 – Apr 21 |
| Connecticut | April 25 | Apr 4 – Apr 21 |
| New York | May 1 | Apr 10 – Apr 27 |
Questions gardeners in New Hampshire ask
When is the best time to plant cauliflower in New Hampshire?
Plant cauliflower transplants outdoors in New Hampshire between April 22 and May 9. That timing is set by New Hampshire's average last spring frost of May 13.
When should I start cauliflower seeds indoors in New Hampshire?
Start seeds indoors between March 25 and April 8, about 6 weeks before the last frost, so the seedlings are ready to plant out from April 22.
Can I plant cauliflower in the fall in New Hampshire?
Yes. For a fall crop, start transplants between June 16 and July 3, so the crop matures in cool weather before New Hampshire's first frost around September 25.
When will cauliflower planted in New Hampshire be ready to harvest?
Planted on time, cauliflower is usually ready from about June 28 to July 28, 60-90 days after transplanting.
When is the last frost in New Hampshire?
On average around May 13, with the first fall frost around September 25 - about 135 frost-free days. Your town may differ by two weeks or more.