Iowa · zones 4b–6a
When to plant sweet potatoes in Iowa.
Sow or transplant between Jun 7 to Jul 22 in a typical year, keyed to Iowa's median last frost around May 1. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Sweet Potatoes dates for a typical Iowa season.
1 · Start indoors
Apr 26 to Jun 10
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Jun 7 to Jul 22
Keyed to the ~May 1 last frost. Sow 3" deep, 14" apart.
Harvest
~110 days later
~2.5 lb per plant over ~1 weeks.
Iowa spans more than one climate: Zone 5 is the most common zone, but the state runs 4b to 6a. 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.