Billings, MT planting zone & frost dates
Billings is in USDA hardiness zone 5a. The last spring frost usually comes around May 10 and the first fall frost around October 1, for a growing season of about 142 days.
Planting calendar for Billings
Dates are counted from the average last spring frost (May 10) 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: Mar 15 – Mar 29 Transplant outdoors: May 17 – May 24 |
| Peppers | Start seeds indoors: Mar 1 – Mar 15 Transplant outdoors: May 24 – May 31 |
| Eggplant | Start seeds indoors: Mar 1 – Mar 15 Transplant outdoors: May 24 – May 31 |
| Broccoli | Start seeds indoors: Mar 1 – Mar 15 Transplant outdoors: Apr 12 – Apr 26 |
| Cabbage | Start seeds indoors: Mar 1 – Mar 15 Transplant outdoors: Apr 12 – Apr 26 |
| Onions (sets) | Plant outdoors: Apr 12 – Apr 26 |
| Peas | Sow outdoors: Mar 29 – Apr 12 |
| Spinach | Sow outdoors: Mar 29 – Apr 12 |
| Lettuce | Sow outdoors: Apr 12 – Apr 26 |
| Carrots | Sow outdoors: Apr 12 – Apr 26 |
| Potatoes | Plant outdoors: Apr 12 – Apr 26 |
| Beans | Sow outdoors: May 17 – May 24 |
| Sweet corn | Sow outdoors: May 17 – May 24 |
| Cucumbers | Sow outdoors: May 17 – May 24 |
| Squash & zucchini | Sow outdoors: May 17 – May 24 |
| Basil | Start seeds indoors: Mar 29 – Apr 12 Transplant outdoors: May 17 – May 24 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 6 (8 weeks before the average first fall frost on Oct 1).
Useful for zone 5a 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 | Apr 26 | May 10 | May 24 |
| First 32°F frost in fall is before | Oct 15 | Oct 1 | Sep 19 |
How to read it: in spring there is a 10% chance of a frost after May 24, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 19. A hard freeze (28°F) usually ends around April 27.
Hardiness zone by ZIP code in Billings
- 59101 zone 5a
- 59102 zone 5a
- 59103 zone 5a
- 59104 zone 5a
- 59105 zone 5a
- 59106 zone 5a
- 59107 zone 5a
- 59108 zone 5a
- 59111 zone 5a
- 59112 zone 5a
- 59114 zone 5a
- 59115 zone 5a
- 59116 zone 5a
- 59117 zone 5a
Nearby cities
Questions
What growing zone is Billings, MT?
Billings is in USDA Plant Hardiness Zone 5a (average extreme winter low -20°F to -15°F), according to the USDA 2023 map.
When is the last frost in Billings?
The average last spring frost (32°F) in Billings is May 10. There is still a 10% chance of frost until May 24.
When can I plant tomatoes in Billings?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 17 – May 24. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Billings Wtp, MT (USC00240802), 2.0 km (1.2 mi) from the city center, elevation 944 m, based on 28 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.