Iowa · zones 4b–6a
When to plant broccoli in Iowa.
Sow or transplant between Mar 10 to Apr 7 in a typical year, keyed to Iowa's median last frost around May 1. A second, fall sowing fits Jun 23 to Aug 2. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Broccoli dates for a typical Iowa season.
1 · Start indoors
Jan 27 to Feb 24
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Mar 10 to Apr 7
Keyed to the ~May 1 last frost. Sow 0.5" deep, 18" apart.
Fall round
Jun 23 to Aug 2
Counted back from the ~Oct 7 first frost.
Harvest
~60 days later
~1.2 lb per plant over ~3 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.