When to plant broccoli 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). Broccoli needs 60–85 days to mature, which fits comfortably within New Hampshire's growing season.
When to plant broccoli 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 broccoli 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 7.0. 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. Give it steady, even moisture, about an inch of water a week from rain or the hose.
- Watch for pests and problems. Pests: cabbage worm, cabbage looper, aphids, flea beetle, cabbage root maggot. Diseases and disorders: clubroot, black rot, downy mildew.
- Harvest (from about Jun 28 – Jul 23). Broccoli takes 60-85 days to reach harvest. Days to maturity counted from transplant. Keep cutting side shoots after the main head for weeks. Spring crop must size up before heat or it buttons.
Figures come from our crop data; dates use New Hampshire’s average frost dates. More in the full broccoli growing guide.
Broccoli 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 broccoli dates shift with them.
When to plant broccoli 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 broccoli in New Hampshire?
Plant broccoli 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 broccoli 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 broccoli 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 broccoli planted in New Hampshire be ready to harvest?
Planted on time, broccoli is usually ready from about June 28 to July 23, 60-85 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.