Illinois · zones 5b–6b
When to plant tomatoes in Illinois.
Sow or transplant between Apr 27 to Jun 27 in a typical year, keyed to Illinois's median last frost around Apr 20. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Tomatoes dates for a typical Illinois season.
1 · Start indoors
Mar 16 to May 16
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Apr 27 to Jun 27
Keyed to the ~Apr 20 last frost. Sow 0.25" deep, 24" apart.
Harvest
~73 days later
~12 lb per plant over ~8 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.