When to plant potatoes in Wisconsin
Wisconsin’s average last spring frost is May 10, and the first fall frost typically arrives around September 30 — about 143 frost-free days (USDA zones 3b, 4a, 4b, 5a, 5b). Potato needs 70–120 days to mature, which fits comfortably within Wisconsin's growing season.
When to plant potatoes in Wisconsin: the short answer
For a spring planting, sow Apr 21 – May 10. Seeds germinate in soil from 45 to 80°F.
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 potatoes in Wisconsin, step by step
- Prepare the bed. They need at least six to eight hours of direct sun a day and loose soil at least 18 inches deep, with a pH between 4.8 and 6.5. Dig in compost before planting.
- Sow outdoors (Apr 21 – May 10). Space plants about 12 inches apart in rows 32 inches apart, sowing seed 4 inches deep. It tolerates a light frost but not a hard freeze. As a cool-season crop it does best before summer heat arrives in Wisconsin.
- 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: Colorado potato beetle, flea beetle, wireworm, aphids. Diseases and disorders: late blight, early blight, common scab, blackleg.
- Harvest (from about Jul 5 – Aug 24). Potato takes 70-120 days to reach harvest. Plant certified seed potatoes, not grocery-store ones. Hill soil or mulch over the stems as they grow to stop greening. New potatoes ~10 weeks in; storage potatoes after the tops die back.
Figures come from our crop data; dates use Wisconsin’s average frost dates. More in the full potato growing guide.
Potato planting dates by USDA zone in Wisconsin
Wisconsin spans USDA zones 3b, 4a, 4b, 5a, 5b. 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 potato dates shift with them.
When to plant potatoes in nearby states
Questions gardeners in Wisconsin ask
When is the best time to plant potatoes in Wisconsin?
Sow potatoes in Wisconsin between April 21 and May 10. That timing is set by Wisconsin's average last spring frost of May 10.
When will potatoes planted in Wisconsin be ready to harvest?
Planted on time, potatoes are usually ready from about July 5 to August 24, 70-120 days after sowing.
When is the last frost in Wisconsin?
On average around May 10, with the first fall frost around September 30 - about 143 frost-free days. Your town may differ by two weeks or more.