When to plant zucchini / summer squash in Pennsylvania
Pennsylvania’s average last spring frost is May 1, and the first fall frost typically arrives around October 10 — about 162 frost-free days (USDA zones 5a, 5b, 6a, 6b, 7a, 7b). Zucchini / Summer Squash needs 45–60 days to mature, which fits comfortably within Pennsylvania's growing season.
Pennsylvania covers a wide range of climates, so your exact frost dates may differ from the state average by two weeks or more. For dates tuned to your town, use the calendar generator.
When to plant zucchini / summer squash in Pennsylvania: the short answer
For a spring planting, plant out May 1 – May 18, with seeds started indoors Apr 3 – Apr 17. Wait until the soil is at least 60°F and frost is over.
Succession sow again in Pennsylvania: Jun 5 · Jul 3 · Jul 31
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 Pennsylvania, step by step
- Start seeds indoors (Apr 3 – Apr 17). 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 1 – May 18). 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 Jun 22 – Jul 7). 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 Pennsylvania’s average frost dates. More in the full zucchini / summer squash growing guide.
Zucchini planting dates by USDA zone in Pennsylvania
Pennsylvania spans USDA zones 5a, 5b, 6a, 6b, 7a, 7b. 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 |
|---|---|---|
| Pennsylvania (this page) | May 1 | May 1 – May 18 |
| New Jersey | April 20 | Apr 20 – May 7 |
| Delaware | April 14 | Apr 14 – May 1 |
| Maryland | April 14 | Apr 14 – May 1 |
| District of Columbia | April 10 | Apr 10 – Apr 27 |
| Virginia | April 15 | Apr 15 – May 2 |
| West Virginia | May 5 | May 5 – May 22 |
Questions gardeners in Pennsylvania ask
When is the best time to plant zucchini / summer squash in Pennsylvania?
Plant zucchini / summer squash transplants outdoors in Pennsylvania between May 1 and May 18. That timing is set by Pennsylvania's average last spring frost of May 1; Pennsylvania spans several climates, so cooler and higher parts of the state run later.
When should I start zucchini / summer squash seeds indoors in Pennsylvania?
Start seeds indoors between April 3 and April 17, about 3 weeks before the last frost, so the seedlings are ready to plant out from May 1.
Can I plant zucchini / summer squash in the fall in Pennsylvania?
Yes. For a fall crop, sow between July 8 and July 25, so the crop matures in cool weather before Pennsylvania's first frost around October 10.
When will zucchini / summer squash planted in Pennsylvania be ready to harvest?
Planted on time, zucchini / summer squash is usually ready from about June 22 to July 7, 45-60 days after planting.
When is the last frost in Pennsylvania?
On average around May 1, with the first fall frost around October 10 - about 162 frost-free days. Your town may differ by two weeks or more.