Iowa · zones 4b–6a
When to plant basil in Iowa.
Sow or transplant between May 22 to Aug 7 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
Basil dates for a typical Iowa season.
1 · Start indoors
Apr 10 to Jun 26
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
May 22 to Aug 7
Keyed to the ~May 1 last frost. Sow 0.25" deep, 8" apart.
Harvest
~40 days later
~0.5 lb per plant over ~12 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.