When to plant zucchini / summer squash in Delaware
Delaware’s average last spring frost is April 14, and the first fall frost typically arrives around October 22 — about 191 frost-free days (USDA zones 7a, 7b). Zucchini / Summer Squash needs 45–60 days to mature, which fits comfortably within Delaware's growing season.
When to plant zucchini / summer squash in Delaware: the short answer
For a spring planting, plant out Apr 14 – May 1, with seeds started indoors Mar 17 – Mar 31. Wait until the soil is at least 60°F and frost is over.
Succession sow again in Delaware: May 19 · Jun 16 · Jul 14 · Aug 11
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 Delaware, step by step
- Start seeds indoors (Mar 17 – Mar 31). 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 (Apr 14 – May 1). 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 5 – Jun 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 Delaware’s average frost dates. More in the full zucchini / summer squash growing guide.
When to plant zucchini / summer squash in nearby states
| State | Last frost | Plant out |
|---|---|---|
| Delaware (this page) | April 14 | Apr 14 – May 1 |
| New Jersey | April 20 | Apr 20 – May 7 |
| Pennsylvania | May 1 | May 1 – May 18 |
| 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 Delaware ask
When is the best time to plant zucchini / summer squash in Delaware?
Plant zucchini / summer squash transplants outdoors in Delaware between April 14 and May 1. That timing is set by Delaware's average last spring frost of April 14.
When should I start zucchini / summer squash seeds indoors in Delaware?
Start seeds indoors between March 17 and March 31, about 3 weeks before the last frost, so the seedlings are ready to plant out from April 14.
Can I plant zucchini / summer squash in the fall in Delaware?
Yes. For a fall crop, sow between July 20 and August 6, so the crop matures in cool weather before Delaware's first frost around October 22.
When will zucchini / summer squash planted in Delaware be ready to harvest?
Planted on time, zucchini / summer squash is usually ready from about June 5 to June 20, 45-60 days after planting.
When is the last frost in Delaware?
On average around April 14, with the first fall frost around October 22 - about 191 frost-free days. Your town may differ by two weeks or more.