Hardin, MT frost dates
Last spring frostMay 13median date
First fall frostSep 29median date
Growing season139 daysfrost-free
Hardiness zone4bZone 4b
How Hardin compares
- In 8 years out of 10, the last spring frost in Hardin falls between April 30 and May 26, a 26-day window. The first fall frost falls between September 14 and October 10.
- The median last frost is 6 days earlier than the Montana median of May 19.
- Its 139-day growing season is longer than 79% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 5 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 166 nights a year at or below 32°F.
- Compared with Billings, MT, 71 km away, the last frost here is 9 days later than there and the growing season is 17 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 30 |
| 50% (median) | May 13 |
| 10% (safe for tender plants) | May 26 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 14 |
| 50% (median) | September 29 |
| 90% (late) | October 10 |
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 Hardin, MT
Hardin, MT frost dates — last frost May 13, first frost Sep 29, zone 4b. whenisthelastfrost.com
Crop
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Start indoors: Feb 18 to Mar 4Transplant outside: Apr 15 to Apr 29
Start indoors: Mar 4 to Mar 18Transplant outside: May 27 to Jun 10
Start indoors: Mar 4 to Mar 18Transplant outside: May 27 to Jun 10
Start indoors: Mar 18 to Apr 1Transplant outside: May 20 to Jun 3
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 22 to May 6Sow outdoors: Apr 15 to May 20Plant for fall: Aug 4 to Sep 1
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 15 to Apr 29Sow outdoors: Apr 15 to Apr 29Plant for fall: Jul 21 to Aug 11
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 29 to May 13Plant for fall: Jun 23 to Jul 14
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 22 to May 6Plant for fall: Jun 23 to Jul 14
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 29 to May 13Plant for fall: Jun 23 to Jul 14
Start indoors: Apr 1 to Apr 15Transplant outside: Jun 3 to Jun 17Sow outdoors: Jun 3 to Jun 17
Start indoors: Apr 1 to Apr 15Transplant outside: May 20 to Jun 3
Sow outdoors: Apr 1 to Apr 22Plant for fall: Jul 7 to Jul 28
Sow outdoors: Apr 1 to Apr 22Plant for fall: Aug 4 to Aug 25
Sow outdoors: Apr 8 to May 20Plant for fall: Aug 18 to Sep 8
Start indoors: Apr 15 to Apr 22Transplant outside: May 27 to Jun 3Sow outdoors: May 20 to Jun 3Plant for fall: Jul 14 to Jul 28
Start indoors: Apr 15 to Apr 22Sow outdoors: May 20 to Jun 3Plant for fall: Jul 21 to Aug 4
Start indoors: Apr 15 to Apr 22Sow outdoors: May 20 to Jun 3
Start indoors: Apr 15 to Apr 22Transplant outside: May 27 to Jun 10
Sow outdoors: Apr 22 to May 20Plant for fall: Jul 7 to Jul 21
Sow outdoors: Apr 22 to May 20Plant for fall: Jul 21 to Aug 4
Sow outdoors: Apr 22 to May 13
Sow outdoors: Apr 29 to May 27Plant for fall: Jul 21 to Aug 4
Sow outdoors: Apr 29 to May 20Plant for fall: Aug 4 to Aug 25
Sow outdoors: May 20 to Jun 10Plant for fall: Jul 14 to Jul 28
Sow outdoors: May 20 to Jun 3
Transplant outside: May 27 to Jun 17
Plant for fall: Sep 15 to Oct 20
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Hardin, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 18 – Mar 4 | Apr 15 – Apr 29 | — | — |
| Peppers | Mar 4 – Mar 18 | May 27 – Jun 10 | — | — |
| Eggplant | Mar 4 – Mar 18 | May 27 – Jun 10 | — | — |
| Tomatoes | Mar 18 – Apr 1 | May 20 – Jun 3 | — | — |
| Lettuce | Mar 18 – Apr 1 | Apr 22 – May 6 | Apr 15 – May 20 | Aug 4 – Sep 1 |
| Kale | Mar 18 – Apr 1 | Apr 15 – Apr 29 | Apr 15 – Apr 29 | Jul 21 – Aug 11 |
| Broccoli | Mar 18 – Apr 1 | Apr 29 – May 13 | — | Jun 23 – Jul 14 |
| Cabbage | Mar 18 – Apr 1 | Apr 22 – May 6 | — | Jun 23 – Jul 14 |
| Cauliflower | Mar 18 – Apr 1 | Apr 29 – May 13 | — | Jun 23 – Jul 14 |
| Okra | Apr 1 – Apr 15 | Jun 3 – Jun 17 | Jun 3 – Jun 17 | — |
| Basil | Apr 1 – Apr 15 | May 20 – Jun 3 | — | — |
| Peas | — | — | Apr 1 – Apr 22 | Jul 7 – Jul 28 |
| Spinach | — | — | Apr 1 – Apr 22 | Aug 4 – Aug 25 |
| Radishes | — | — | Apr 8 – May 20 | Aug 18 – Sep 8 |
| Cucumbers | Apr 15 – Apr 22 | May 27 – Jun 3 | May 20 – Jun 3 | Jul 14 – Jul 28 |
| Zucchini & Summer Squash | Apr 15 – Apr 22 | — | May 20 – Jun 3 | Jul 21 – Aug 4 |
| Winter Squash & Pumpkins | Apr 15 – Apr 22 | — | May 20 – Jun 3 | — |
| Melons & Watermelon | Apr 15 – Apr 22 | May 27 – Jun 10 | — | — |
| Carrots | — | — | Apr 22 – May 20 | Jul 7 – Jul 21 |
| Beets | — | — | Apr 22 – May 20 | Jul 21 – Aug 4 |
| Potatoes | — | — | Apr 22 – May 13 | — |
| Swiss Chard | — | — | Apr 29 – May 27 | Jul 21 – Aug 4 |
| Cilantro | — | — | Apr 29 – May 20 | Aug 4 – Aug 25 |
| Green Beans | — | — | May 20 – Jun 10 | Jul 14 – Jul 28 |
| Sweet Corn | — | — | May 20 – Jun 3 | — |
| Sweet Potatoes | — | May 27 – Jun 17 | — | — |
| Garlic | — | — | — | Sep 15 – Oct 20 |
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 Hardin, MT weather station, 2 km away (elevation 2,881 ft (878 m)).
Frost dates near Hardin
- Crow Agency May 13 · Sep 29
- Garryowen May 13 · Sep 29
- Pompeys Pillar May 22 · Sep 22
- Bighorn May 26 · Sep 16
- Custer May 22 · Sep 22
- Saint Xavier May 7 · Oct 5
- Ballantine May 12 · Sep 25
- Worden May 12 · Sep 25
- Lodge Grass May 21 · Sep 17
- Huntley May 12 · Sep 25
Frequently asked questions
When is the last frost in Hardin, MT?
The median last spring frost in Hardin, MT is May 13. There is still about a 10% chance of frost after May 26, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Hardin, MT?
The median first fall frost is September 29, with about a 10% chance of frost before September 14.
How long is the growing season in Hardin, MT?
About 139 days between the median last spring frost and first fall frost.
What planting zone is Hardin, MT?
Hardin, MT is in USDA hardiness zone 4b.