Kalispell, MT Frost Dates
Average frost dates, USDA hardiness zone, and growing season length for Kalispell, Montana.
Gardening in Kalispell
Flathead Valley's hub city sits near Glacier National Park in a mountain valley that combines stunning scenery with surprisingly workable growing conditions.
Zone 5b with 125 frost-free days. The Flathead Valley is broader and warmer than surrounding mountain areas. Flathead Lake moderates temperatures for lakeside gardens. The glacial soil is variable but generally fertile.
The Flathead Valley's cherry orchards prove the microclimate works for fruit. Home gardeners share those valley-bottom advantages. The Kalispell Farmers Market serves a growing food-conscious community.
What This Means for Kalispell Gardeners
The average last spring frost in Kalispell is around May 18, and the average first fall frost arrives around September 20. That gives you approximately 125 frost-free days to work with.
125 frost-free days means every warm day counts. Focus on cold-hardy crops that thrive in your moderate temperatures: kale, lettuce, peas, radishes, potatoes, and root vegetables. For warm-season crops, choose only the shortest-season varieties (sub-65-day tomatoes, 55-day beans) and start everything indoors. Season extension — row covers, cold frames, plastic mulch — isn't a luxury here, it's essential infrastructure.
These dates are based on NOAA 30-year Climate Normal data for the Kalispell area. Your actual frost dates could shift 2-3 weeks in either direction in any given year. Learn more about our data sources.
What to Grow in Kalispell
With 125 frost-free days, Kalispell gardeners need to plan strategically — start warm-season crops indoors and choose short-season varieties. Cool-season crops are your strength, thriving in the moderate temperatures that define your growing window. Recommended starting points: kale, lettuce, peas, carrots, potatoes, radishes, garlic, and short-season tomatoes.
See the full Montana planting guide for all 40 plants: Montana Planting Calendar. Or enter your zip code for exact planting dates personalized to Kalispell.
More About Zone 5B
Kalispell is in USDA Hardiness Zone 5B, which means average annual extreme minimum temperatures between -15°F to -10°F. View the full Zone 5B planting guide.
See the complete planting calendar for Montana: Montana Planting Calendar.
Other Cities in Montana
Frequently Asked Questions
These dates are based on NOAA's 30-year Climate Normal data for the Kalispell area. They represent historical averages, not predictions. In any given year, the actual last frost could be 2-3 weeks earlier or later. Microclimates within Kalispell (urban heat islands, hilltops, low-lying valleys) can also shift your local frost dates by a week or more.
Start everything possible indoors — your 125-day season doesn't leave room for a slow start. Direct sow only the fastest, hardiest crops (radishes, lettuce, peas) 3-4 weeks before last frost (May 18). Choose short-season varieties for warm crops. Enter your zip code for exact dates.