When to plant zucchini / summer squash in Maine
Maine’s average last spring frost is May 14, and the first fall frost typically arrives around September 25 — about 134 frost-free days (USDA zones 3b, 4a, 4b, 5a, 5b, 6a). Zucchini / Summer Squash needs 45–60 days to mature, which fits comfortably within Maine's growing season.
When to plant zucchini / summer squash in Maine: the short answer
For a spring planting, plant out May 14 – May 31, with seeds started indoors Apr 16 – Apr 30. Wait until the soil is at least 60°F and frost is over.
Succession sow again in Maine: Jun 18 · Jul 16
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 Maine, step by step
- Start seeds indoors (Apr 16 – Apr 30). 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 14 – May 31). 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 5 – Jul 20). 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 Maine’s average frost dates. More in the full zucchini / summer squash growing guide.
Zucchini planting dates by USDA zone in Maine
Maine 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 |
|---|---|---|
| Maine (this page) | May 14 | May 14 – May 31 |
| New Hampshire | May 13 | May 13 – May 30 |
| 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 Maine ask
When is the best time to plant zucchini / summer squash in Maine?
Plant zucchini / summer squash transplants outdoors in Maine between May 14 and May 31. That timing is set by Maine's average last spring frost of May 14.
When should I start zucchini / summer squash seeds indoors in Maine?
Start seeds indoors between April 16 and April 30, about 3 weeks before the last frost, so the seedlings are ready to plant out from May 14.
Can I plant zucchini / summer squash in the fall in Maine?
Yes. For a fall crop, sow between June 23 and July 10, so the crop matures in cool weather before Maine's first frost around September 25.
When will zucchini / summer squash planted in Maine be ready to harvest?
Planted on time, zucchini / summer squash is usually ready from about July 5 to July 20, 45-60 days after planting.
When is the last frost in Maine?
On average around May 14, with the first fall frost around September 25 - about 134 frost-free days. Your town may differ by two weeks or more.