When to plant zucchini / summer squash 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). Zucchini / Summer Squash needs 45–60 days to mature, which fits comfortably within New Hampshire's growing season.
When to plant zucchini / summer squash in New Hampshire: the short answer
For a spring planting, plant out May 13 – May 30, with seeds started indoors Apr 15 – Apr 29. Wait until the soil is at least 60°F and frost is over.
Succession sow again in New Hampshire: Jun 17 · Jul 15
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 zucchini / summer squash in New Hampshire, step by step
- Start seeds indoors (Apr 15 – Apr 29). Sow seeds 1 inch deep in seed-starting mix under bright light. They take 5-10 days to sprout, fastest in soil around 85°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 14 inches deep, with a pH between 5.5 and 7.5. Dig in compost before planting.
- Plant out (May 13 – May 30). Space plants about 30 inches apart in rows 42 inches apart. It is killed by frost, so nothing goes outside until the danger has passed.
- 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: squash vine borer, squash bug, striped cucumber beetle, aphids. Diseases and disorders: powdery mildew, bacterial wilt, blossom-end rot (calcium disorder).
- Harvest (from about Jul 4 – Jul 19). Zucchini / Summer Squash takes 45-60 days to reach harvest. One or two plants feed a household. A second sowing in early-mid summer dodges the first vine borer generation.
Figures come from our crop data; dates use New Hampshire’s average frost dates. More in the full zucchini / summer squash growing guide.
Zucchini 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 zucchini / summer squash dates shift with them.
When to plant zucchini / summer squash in nearby states
| State | Last frost | Plant out |
|---|---|---|
| New Hampshire (this page) | May 13 | May 13 – May 30 |
| Maine | May 14 | May 14 – May 31 |
| Vermont | May 14 | May 14 – May 31 |
| Massachusetts | April 24 | Apr 24 – May 11 |
| Rhode Island | April 25 | Apr 25 – May 12 |
| Connecticut | April 25 | Apr 25 – May 12 |
| New York | May 1 | May 1 – May 18 |
Questions gardeners in New Hampshire ask
When is the best time to plant zucchini / summer squash in New Hampshire?
Plant zucchini / summer squash transplants outdoors in New Hampshire between May 13 and May 30. That timing is set by New Hampshire's average last spring frost of May 13.
When should I start zucchini / summer squash seeds indoors in New Hampshire?
Start seeds indoors between April 15 and April 29, about 3 weeks before the last frost, so the seedlings are ready to plant out from May 13.
Can I plant zucchini / summer squash in the fall in New Hampshire?
Yes. For a fall crop, sow between June 23 and July 10, so the crop matures in cool weather before New Hampshire's first frost around September 25.
When will zucchini / summer squash planted in New Hampshire be ready to harvest?
Planted on time, zucchini / summer squash is usually ready from about July 4 to July 19, 45-60 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.