USDA hardiness zones — 2023 map
Montana hardiness zones — USDA planting zone map + what to grow
Zones 3a-6a · most of Montana is zone 4b · West region
MontanaUSDA zone range & map
On the 2023 USDA Plant Hardiness Zone Map, Montana spans zones 3a-6a. The map shades the state from the high mountain valleys and northern plains (zone 3a) through to the lower western valleys near Missoula (zone 6a). The single most common half-zone across the populated state is zone 4b — that is the figure to use if you only remember one number for Montana. Montana is a cold, short-season state with big elevation effects. Western valleys are milder than the high plains and mountain basins.
| USDA zone range | Zones 3a-6a |
|---|---|
| Most common zone | Zone 4b |
| Coldest area | the high mountain valleys and northern plains (zone 3a) |
| Warmest area | the lower western valleys near Missoula (zone 6a) |
| Average last spring frost | late May |
| Average first fall frost | mid-September |
Source: USDA 2023 Plant Hardiness Zone Map (1991-2020 normals). Frost averages: NOAA/NCEI 1991-2020 climate normals. Local ZIP-level zones and frost dates can differ from these statewide figures.
Montana hardiness zones by major city
Zones shift across Montana with elevation and distance from the coast. Here is the 2023 USDA half-zone for the largest cities:
| City | USDA zone |
|---|---|
| Billings | Zone 5a |
| Missoula | Zone 5b |
| Bozeman | Zone 5a |
| Great Falls | Zone 4b |
| Kalispell | Zone 5a |
Need your exact zone? Run the ZIP-code zone finder for a precise half-zone and frost dates for your address.
ZIP-code zones in Montana
Statewide ranges hide a lot. Tap your area for its exact USDA half-zone, last and first frost dates, and what to plant now:
- Livingston 59047 — Zone 4b
- Billings 59101 — Zone 5a
- Billings (West) 59102 — Zone 5a
- Great Falls 59405 — Zone 4b
- Helena 59601 — Zone 5a
- Butte 59701 — Zone 4a
- Bozeman 59715 — Zone 4b
- Bozeman (West) 59718 — Zone 4b
- Missoula 59801 — Zone 5b
- Missoula (East) 59802 — Zone 5b
- Kalispell 59901 — Zone 5a
What Montana's zone range means for planting
Your hardiness zone tells you which perennials, shrubs, and trees will survive a typical Montana winter, and it anchors when tender crops can go outside. Because Montana spans 3a-6a, two gardeners in the same state can have very different planting calendars.
- Pick perennials hardy to your local zone. Across most of Montana that means at least zone 4b; gardeners in the high mountain valleys and northern plains (zone 3a) should choose hardier plants.
- Anchor tender crops to your frost dates. With a last spring frost around late May and first fall frost around mid-September, set out tomatoes, peppers, and basil after the last frost and protect them before the first.
- Adjust for your microclimate. Urban heat, a south-facing slope, or a cold valley pocket can shift your effective zone and frost dates by a half-zone or more from the statewide figure.
Find your exact zone in Montana
The 3a-6a range is statewide. Growli pins your hardiness zone and frost dates to your exact ZIP code and sends a push notification before any forecast frost night for your saved location.
Frequently asked questions
What hardiness zone is Montana?
Montana spans USDA hardiness zones 3a-6a on the 2023 USDA Plant Hardiness Zone Map. The most common zone — covering the largest share of the populated state — is zone 4b. The coldest areas are the high mountain valleys and northern plains (zone 3a) and the warmest are the lower western valleys near Missoula (zone 6a).
When is the last frost in Montana?
Across most of Montana the average last spring frost falls around late May and the first fall frost around mid-September. These are statewide averages — colder, higher areas run later in spring and earlier in fall, so check a ZIP-level estimate for your exact spot.
What grows well in Montana?
Montana is a cold, short-season state with big elevation effects. Western valleys are milder than the high plains and mountain basins. Match plants to your local half-zone within the 3a-6a range: choose varieties hardy to at least zone 4b for reliable overwintering, and time tender crops around your local frost dates. The zone 4 planting guide lists vegetables, fruit, and ornamentals suited to most of the state.
Why does Montana have more than one hardiness zone?
Hardiness zones track the average annual coldest temperature, which changes with latitude, elevation, distance from water, and urban heat. That is why Montana ranges from the high mountain valleys and northern plains (zone 3a) to the lower western valleys near Missoula (zone 6a) — a span of 3a-6a — even though it is a single state.
Did Montana's hardiness zone change in 2023?
The USDA updated the Plant Hardiness Zone Map in November 2023 using 1991-2020 climate data. About half the country, including parts of Montana, shifted to the next warmer half-zone versus the 2012 map. The 3a-6a range here reflects the current 2023 map. Always confirm your address against the official USDA map for plant-survival decisions.