Kalispell, MT planting zone & frost dates
Kalispell is in USDA hardiness zone 5b. The last spring frost usually comes around May 31 and the first fall frost around September 10, for a growing season of about 100 days.
Planting calendar for Kalispell
Dates are counted from the average last spring frost (May 31) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Apr 5 – Apr 19 Transplant outdoors: Jun 7 – Jun 14 |
| Peppers | Start seeds indoors: Mar 22 – Apr 5 Transplant outdoors: Jun 14 – Jun 21 |
| Eggplant | Start seeds indoors: Mar 22 – Apr 5 Transplant outdoors: Jun 14 – Jun 21 |
| Broccoli | Start seeds indoors: Mar 22 – Apr 5 Transplant outdoors: May 3 – May 17 |
| Cabbage | Start seeds indoors: Mar 22 – Apr 5 Transplant outdoors: May 3 – May 17 |
| Onions (sets) | Plant outdoors: May 3 – May 17 |
| Peas | Sow outdoors: Apr 19 – May 3 |
| Spinach | Sow outdoors: Apr 19 – May 3 |
| Lettuce | Sow outdoors: May 3 – May 17 |
| Carrots | Sow outdoors: May 3 – May 17 |
| Potatoes | Plant outdoors: May 3 – May 17 |
| Beans | Sow outdoors: Jun 7 – Jun 14 |
| Sweet corn | Sow outdoors: Jun 7 – Jun 14 |
| Cucumbers | Sow outdoors: Jun 7 – Jun 14 |
| Squash & zucchini | Sow outdoors: Jun 7 – Jun 14 |
| Basil | Start seeds indoors: Apr 19 – May 3 Transplant outdoors: Jun 7 – Jun 14 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Jul 16 (8 weeks before the average first fall frost on Sep 10).
Useful for zone 5b gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Cold frame / mini greenhouse — adds weeks to a short season
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | May 13 | May 31 | Jun 22 |
| First 32°F frost in fall is before | Sep 25 | Sep 10 | Aug 26 |
How to read it: in spring there is a 10% chance of a frost after June 22, so that is a safe date for tender plants. In fall there is a 10% chance of frost before August 26. A hard freeze (28°F) usually ends around May 10.
Hardiness zone by ZIP code in Kalispell
- 59901 zone 5b
- 59903 zone 5b
- 59904 zone 5b
Nearby cities
Questions
What growing zone is Kalispell, MT?
Kalispell is in USDA Plant Hardiness Zone 5b (average extreme winter low -15°F to -10°F), according to the USDA 2023 map.
When is the last frost in Kalispell?
The average last spring frost (32°F) in Kalispell is May 31. There is still a 10% chance of frost until June 22.
When can I plant tomatoes in Kalispell?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Jun 7 – Jun 14. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Kalispell Glacier Ap, MT (USC00244558), 12.6 km (7.8 mi) from the city center, elevation 901 m, based on 26 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.