When to plant zucchini / summer squash in Wyoming
Wyoming’s average last spring frost is May 20, and the first fall frost typically arrives around September 15 — about 118 frost-free days (USDA zones 3a, 3b, 4a, 4b, 5a, 6a). Zucchini / Summer Squash needs 45–60 days to mature, which fits comfortably within Wyoming's growing season.
Wyoming 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 Wyoming: the short answer
For a spring planting, plant out May 20 – Jun 6, with seeds started indoors Apr 22 – May 6. Wait until the soil is at least 60°F and frost is over.
Succession sow again in Wyoming: Jun 24
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 Wyoming, step by step
- Start seeds indoors (Apr 22 – May 6). 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 20 – Jun 6). 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 11 – Jul 26). 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 Wyoming’s average frost dates. More in the full zucchini / summer squash growing guide.
Zucchini planting dates by USDA zone in Wyoming
Wyoming spans USDA zones 3a, 3b, 4a, 4b, 5a, 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
Questions gardeners in Wyoming ask
When is the best time to plant zucchini / summer squash in Wyoming?
Plant zucchini / summer squash transplants outdoors in Wyoming between May 20 and June 6. That timing is set by Wyoming's average last spring frost of May 20; Wyoming spans several climates, so cooler and higher parts of the state run later.
When should I start zucchini / summer squash seeds indoors in Wyoming?
Start seeds indoors between April 22 and May 6, about 3 weeks before the last frost, so the seedlings are ready to plant out from May 20.
Can I plant zucchini / summer squash in the fall in Wyoming?
Yes. For a fall crop, sow between June 13 and June 30, so the crop matures in cool weather before Wyoming's first frost around September 15.
When will zucchini / summer squash planted in Wyoming be ready to harvest?
Planted on time, zucchini / summer squash is usually ready from about July 11 to July 26, 45-60 days after planting.
When is the last frost in Wyoming?
On average around May 20, with the first fall frost around September 15 - about 118 frost-free days. Your town may differ by two weeks or more.