White Sulphur Springs, MT frost dates
Last spring frostJun 4median date
First fall frostSep 11median date
Growing season99 daysfrost-free
Hardiness zone4bZone 4b
How White Sulphur Springs compares
- In 8 years out of 10, the last spring frost in White Sulphur Springs falls between May 21 and June 20, a 30-day window. The first fall frost falls between August 27 and September 27.
- The median last frost is 16 days later than the Montana median of May 19.
- Its 99-day growing season is longer than 10% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 27 days later than the zone 4b median of May 8. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 4b chart.
- The weather station records an average of 199 nights a year at or below 32°F.
- Compared with Great Falls, MT, 101 km away, the last frost here is 29 days later than there and the growing season is 49 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 21 |
| 50% (median) | June 4 |
| 10% (safe for tender plants) | June 20 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | August 27 |
| 50% (median) | September 11 |
| 90% (late) | September 27 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for White Sulphur Springs, MT
White Sulphur Springs, MT frost dates — last frost Jun 4, first frost Sep 11, zone 4b. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Mar 12 to Mar 26Transplant outside: May 7 to May 21
Start indoors: Mar 26 to Apr 9Transplant outside: Jun 18 to Jul 2
Start indoors: Mar 26 to Apr 9Transplant outside: Jun 18 to Jul 2
Start indoors: Apr 9 to Apr 23Transplant outside: Jun 11 to Jun 25
Start indoors: Apr 9 to Apr 23Transplant outside: May 14 to May 28Sow outdoors: May 7 to Jun 11Plant for fall: Jul 17 to Aug 14
Start indoors: Apr 9 to Apr 23Transplant outside: May 7 to May 21Sow outdoors: May 7 to May 21Plant for fall: Jul 3 to Jul 24
Start indoors: Apr 9 to Apr 23Transplant outside: May 21 to Jun 4
Start indoors: Apr 9 to Apr 23Transplant outside: May 14 to May 28
Start indoors: Apr 9 to Apr 23Transplant outside: May 21 to Jun 4
Start indoors: Apr 23 to May 7Transplant outside: Jun 25 to Jul 9Sow outdoors: Jun 25 to Jul 9
Start indoors: Apr 23 to May 7Transplant outside: Jun 11 to Jun 25
Sow outdoors: Apr 23 to May 14Plant for fall: Jun 19 to Jul 10
Sow outdoors: Apr 23 to May 14Plant for fall: Jul 17 to Aug 7
Sow outdoors: Apr 30 to Jun 11Plant for fall: Jul 31 to Aug 21
Start indoors: May 7 to May 14Transplant outside: Jun 18 to Jun 25Sow outdoors: Jun 11 to Jun 25
Start indoors: May 7 to May 14Sow outdoors: Jun 11 to Jun 25
Start indoors: May 7 to May 14Sow outdoors: Jun 11 to Jun 25
Start indoors: May 7 to May 14Transplant outside: Jun 18 to Jul 2
Sow outdoors: May 14 to Jun 11
Sow outdoors: May 14 to Jun 11Plant for fall: Jul 3 to Jul 17
Sow outdoors: May 14 to Jun 4
Sow outdoors: May 21 to Jun 18Plant for fall: Jul 3 to Jul 17
Sow outdoors: May 21 to Jun 11Plant for fall: Jul 17 to Aug 7
Sow outdoors: Jun 11 to Jul 2
Sow outdoors: Jun 11 to Jun 25
Transplant outside: Jun 18 to Jul 9
Plant for fall: Aug 28 to Oct 2
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in White Sulphur Springs, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 12 – Mar 26 | May 7 – May 21 | — | — |
| Peppers | Mar 26 – Apr 9 | Jun 18 – Jul 2 | — | — |
| Eggplant | Mar 26 – Apr 9 | Jun 18 – Jul 2 | — | — |
| Tomatoes | Apr 9 – Apr 23 | Jun 11 – Jun 25 | — | — |
| Lettuce | Apr 9 – Apr 23 | May 14 – May 28 | May 7 – Jun 11 | Jul 17 – Aug 14 |
| Kale | Apr 9 – Apr 23 | May 7 – May 21 | May 7 – May 21 | Jul 3 – Jul 24 |
| Broccoli | Apr 9 – Apr 23 | May 21 – Jun 4 | — | — |
| Cabbage | Apr 9 – Apr 23 | May 14 – May 28 | — | — |
| Cauliflower | Apr 9 – Apr 23 | May 21 – Jun 4 | — | — |
| Okra | Apr 23 – May 7 | Jun 25 – Jul 9 | Jun 25 – Jul 9 | — |
| Basil | Apr 23 – May 7 | Jun 11 – Jun 25 | — | — |
| Peas | — | — | Apr 23 – May 14 | Jun 19 – Jul 10 |
| Spinach | — | — | Apr 23 – May 14 | Jul 17 – Aug 7 |
| Radishes | — | — | Apr 30 – Jun 11 | Jul 31 – Aug 21 |
| Cucumbers | May 7 – May 14 | Jun 18 – Jun 25 | Jun 11 – Jun 25 | — |
| Zucchini & Summer Squash | May 7 – May 14 | — | Jun 11 – Jun 25 | — |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 99 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 7 – May 14 | — | Jun 11 – Jun 25 | — |
| Melons & Watermelon | May 7 – May 14 | Jun 18 – Jul 2 | — | — |
| Carrots | — | — | May 14 – Jun 11 | — |
| Beets | — | — | May 14 – Jun 11 | Jul 3 – Jul 17 |
| Potatoes | — | — | May 14 – Jun 4 | — |
| Swiss Chard | — | — | May 21 – Jun 18 | Jul 3 – Jul 17 |
| Cilantro | — | — | May 21 – Jun 11 | Jul 17 – Aug 7 |
| Green Beans | — | — | Jun 11 – Jul 2 | — |
| Sweet Corn | — | — | Jun 11 – Jun 25 | — |
| Sweet Potatoes Warning: Your frost-free season is about 99 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 18 – Jul 9 | — | — |
| Garlic | — | — | — | Aug 28 – Oct 2 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the White Sulphur Springs #2, MT weather station, 15 km away (elevation 5,039 ft (1,536 m)).
Frost dates near White Sulphur Springs
- Neihart Jun 6 · Sep 12
- Ringling frost any month
- Townsend May 19 · Sep 19
- Winston May 19 · Sep 19
- Monarch Jun 6 · Sep 12
- Martinsdale Jun 3 · Sep 8
- Radersburg May 19 · Sep 19
- East Helena May 9 · Sep 30
- Toston May 19 · Sep 19
- Helena May 9 · Sep 30
Frequently asked questions
When is the last frost in White Sulphur Springs, MT?
The median last spring frost in White Sulphur Springs, MT is June 4. There is still about a 10% chance of frost after June 20, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in White Sulphur Springs, MT?
The median first fall frost is September 11, with about a 10% chance of frost before August 27.
How long is the growing season in White Sulphur Springs, MT?
About 99 days between the median last spring frost and first fall frost.
What planting zone is White Sulphur Springs, MT?
White Sulphur Springs, MT is in USDA hardiness zone 4b.