Illinois · zones 5b–6b
When to plant kale in Illinois.
Sow or transplant between Mar 13 to Apr 10 in a typical year, keyed to Illinois's median last frost around Apr 20. A second, fall sowing fits Jul 18 to Sep 2. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Kale dates for a typical Illinois season.
1 · Start indoors
Jan 30 to Feb 27
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Mar 13 to Apr 10
Keyed to the ~Apr 20 last frost. Sow 0.25" deep, 16" apart.
Fall round
Jul 18 to Sep 2
Counted back from the ~Oct 18 first frost.
Harvest
~45 days later
~2 lb per plant over ~16 weeks.
Illinois spans more than one climate: Zone 6 is the most common zone, but the state runs 5b to 6b. 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.