Wisconsin · zones 4a–5b
When to plant watermelon in Wisconsin.
Sow between May 26 to Jul 12 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
Watermelon dates for a typical Wisconsin season.
Direct sow
May 26 to Jul 12
Keyed to the ~May 5 last frost. Sow 1" deep, 36" apart.
Harvest
~85 days later
~20 lb per plant over ~3 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.