Wisconsin · zones 4a–5b
When to plant spinach in Wisconsin.
Sow between Mar 14 to Apr 25 in a typical year, keyed to Wisconsin's median last frost around May 5. A second, fall sowing fits Jul 20 to Sep 7. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Spinach dates for a typical Wisconsin season.
Direct sow
Mar 14 to Apr 25
Keyed to the ~May 5 last frost. Sow 0.5" deep, 3" apart.
Fall round
Jul 20 to Sep 7
Counted back from the ~Oct 3 first frost.
Harvest
~42 days later
~0.25 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.