Montana · zones 4a–5b
When to plant lettuce in Montana.
Sow between Apr 7 to May 22 in a typical year, keyed to Montana's median last frost around May 15. A second, fall sowing fits Jul 10 to Sep 8. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Lettuce dates for a typical Montana season.
Direct sow
Apr 7 to May 22
Keyed to the ~May 15 last frost. Sow 0.25" deep, 6" apart.
Fall round
Jul 10 to Sep 8
Counted back from the ~Sep 23 first frost.
Harvest
~45 days later
~0.4 lb per plant over ~1 weeks.
Montana spans more than one climate: Zone 4 is the most common zone, but the state runs 4a to 5b. 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.