Illinois · zones 5b–6b
When to plant lettuce in Illinois.
Sow between Mar 13 to Apr 27 in a typical year, keyed to Illinois's median last frost around Apr 20. A second, fall sowing fits Aug 4 to Oct 3. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Lettuce dates for a typical Illinois season.
Direct sow
Mar 13 to Apr 27
Keyed to the ~Apr 20 last frost. Sow 0.25" deep, 6" apart.
Fall round
Aug 4 to Oct 3
Counted back from the ~Oct 18 first frost.
Harvest
~45 days later
~0.4 lb per plant over ~1 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.