Wisconsin · zones 4a–5b
When to plant potatoes in Wisconsin.
Sow between Mar 28 to Apr 30 in a typical year, keyed to Wisconsin's median last frost around May 5. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Potatoes dates for a typical Wisconsin season.
Direct sow
Mar 28 to Apr 30
Keyed to the ~May 5 last frost. Sow 4" deep, 12" apart.
Harvest
~90 days later
~3 lb per plant over ~1 weeks.
Wisconsin spans more than one climate: Zone 5 is the most common zone, but the state runs 4a to 5b. That's why the planner works from your ZIP code's frost dates, not your zone — mountain and coastal gardens in the same state can be three weeks apart.