When to plant kale 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). Kale needs 50–65 days to mature, which fits comfortably within New Hampshire's growing season.
When to plant kale in New Hampshire: the short answer
For a spring planting, plant out Apr 15 – May 2, 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 kale 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 70°F. Harden seedlings off for a week before they go outside.
- Prepare the bed. It needs six or more hours of sun for the best growth, though four to six hours in partial shade is enough 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 15 – May 2). Space plants about 16 inches apart in rows 20 inches apart. It tolerates hard frost, so it is one of the first crops to plant. 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, cabbage aphid, flea beetle, harlequin bug. Diseases and disorders: black rot, clubroot, downy mildew.
- Harvest (from about Jun 11 – Jun 26). Kale takes 50-65 days to reach harvest. Flavour turns sweet after a hard frost, so the fall crop is the good one. Pick lower leaves and let the plant keep growing upward.
Figures come from our crop data; dates use New Hampshire’s average frost dates. More in the full kale growing guide.
Kale 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 kale dates shift with them.
When to plant kale in nearby states
| State | Last frost | Plant out |
|---|---|---|
| New Hampshire (this page) | May 13 | Apr 15 – May 2 |
| Maine | May 14 | Apr 16 – May 3 |
| Vermont | May 14 | Apr 16 – May 3 |
| Massachusetts | April 24 | Mar 27 – Apr 13 |
| Rhode Island | April 25 | Mar 28 – Apr 14 |
| Connecticut | April 25 | Mar 28 – Apr 14 |
| New York | May 1 | Apr 3 – Apr 20 |
Questions gardeners in New Hampshire ask
When is the best time to plant kale in New Hampshire?
Plant kale transplants outdoors in New Hampshire between April 15 and May 2. That timing is set by New Hampshire's average last spring frost of May 13.
When should I start kale 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 15.
Can I plant kale in the fall in New Hampshire?
Yes. For a fall crop, sow between June 30 and July 17, so the crop matures in cool weather before New Hampshire's first frost around September 25.
When will kale planted in New Hampshire be ready to harvest?
Planted on time, kale is usually ready from about June 11 to June 26, 50-65 days after planting.
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.