When to plant winter 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). Winter Squash needs 80–110 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 winter 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.
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 winter 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 18 inches deep, with a pH between 5.5 and 7.0. Dig in compost before planting.
- Plant out (May 20 – Jun 6). Space plants about 42 inches apart in rows 72 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. Diseases and disorders: powdery mildew, bacterial wilt.
- Harvest (from about Aug 15 – Sep 14). Winter Squash takes 80-110 days to reach harvest. Needs the whole season - direct sow only where you have 100+ frost-free days. Cure 10 days in warmth after harvest for storage.
Figures come from our crop data; dates use Wyoming’s average frost dates. More in the full winter squash growing guide.
Winter Squash 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 winter squash dates shift with them.
When to plant winter squash in nearby states
Questions gardeners in Wyoming ask
When is the best time to plant winter squash in Wyoming?
Plant winter 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 winter 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.
What is the latest I can plant winter squash in Wyoming?
About June 27. Winter squash needs at least 80 days to mature, and frost around September 15 ends the season, so later plantings risk being cut short.
When will winter squash planted in Wyoming be ready to harvest?
Planted on time, winter squash is usually ready from about August 15 to September 14, 80-110 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.