Illinois · zones 5b–6b
When to plant cucumbers in Illinois.
Sow between Apr 27 to Jul 27 in a typical year, keyed to Illinois's median last frost around Apr 20. A second, fall sowing fits Jun 17 to Jul 18. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Cucumbers dates for a typical Illinois season.
Direct sow
Apr 27 to Jul 27
Keyed to the ~Apr 20 last frost. Sow 1" deep, 12" apart.
Fall round
Jun 17 to Jul 18
Counted back from the ~Oct 18 first frost.
Harvest
~60 days later
~5 lb per plant over ~5 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.