Montana · zones 4a–5b
When to plant zucchini in Montana.
Sow between May 22 to Sep 4 in a typical year, keyed to Montana's median last frost around May 15. A second, fall sowing fits Jun 9 to Jun 28. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Zucchini dates for a typical Montana season.
Direct sow
May 22 to Sep 4
Keyed to the ~May 15 last frost. Sow 1" deep, 24" apart.
Fall round
Jun 9 to Jun 28
Counted back from the ~Sep 23 first frost.
Harvest
~50 days later
~8 lb per plant over ~5 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.