USDA Hardiness Zone 4a
Frost Dates for 59427 — Cut Bank, Montana
Averages from Cut Bank Muni Ap, Mt US, the nearest reporting station, 6.9 miles away.
Plant tender crops after May 24, and expect the first autumn freeze around September 15. That leaves about 113 frost-free days.
- Last spring frost
- May 24
- First fall frost
- September 15
- Growing season
- 113 days
- Hardiness zone
- 4a
50% probability
50% probability
frost-free
-30 to -25°F annual low
Planting calendar for 59427
| When | What to do |
|---|---|
| March 15 – March 29 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| March 29 – April 12 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| April 26 – May 10 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| May 24 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by June 23 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by September 1 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| September 15 onward | Plant garlic, mulch beds, lift tender bulbs Garlic wants a cold spell; bare soil loses structure over winter. |
What these dates mean
Wait until after May 24 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in Cut Bank, Montana are past their last freeze. Harvest before September 15, which leaves roughly 113 frost-free days.
ZIP 59427 sits in USDA hardiness zone 4a, meaning the average coldest night of the year falls between -30 to -25°F. Zone decides what survives the winter; frost dates decide when to plant each spring. They are different questions, and a plant can pass one and fail the other.
These are thirty-year NOAA averages for 1991–2020, not a forecast. Any individual year can frost two to three weeks either side of these dates, so check the actual forecast before planting out.