Manhattan, MT frost dates
Last spring frostMay 26median date
First fall frostSep 15median date
Growing season112 daysfrost-free
Hardiness zone5aZone 5a
How Manhattan compares
- In 8 years out of 10, the last spring frost in Manhattan falls between May 11 and June 12, a 32-day window. The first fall frost falls between September 1 and September 28.
- The median last frost is 7 days later than the Montana median of May 19.
- Its 112-day growing season is longer than 23% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 23 days later than the zone 5a median of May 3. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5a chart.
- The weather station records an average of 200 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 11 |
| 50% (median) | May 26 |
| 10% (safe for tender plants) | June 12 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 1 |
| 50% (median) | September 15 |
| 90% (late) | September 28 |
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 Manhattan, MT
Manhattan, MT frost dates — last frost May 26, first frost Sep 15, zone 5a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Mar 3 to Mar 17Transplant outside: Apr 28 to May 12
Start indoors: Mar 17 to Mar 31Transplant outside: Jun 9 to Jun 23
Start indoors: Mar 17 to Mar 31Transplant outside: Jun 9 to Jun 23
Start indoors: Mar 31 to Apr 14Transplant outside: Jun 2 to Jun 16
Start indoors: Mar 31 to Apr 14Transplant outside: May 5 to May 19Sow outdoors: Apr 28 to Jun 2Plant for fall: Jul 21 to Aug 18
Start indoors: Mar 31 to Apr 14Transplant outside: Apr 28 to May 12Sow outdoors: Apr 28 to May 12Plant for fall: Jul 7 to Jul 28
Start indoors: Mar 31 to Apr 14Transplant outside: May 12 to May 26
Start indoors: Mar 31 to Apr 14Transplant outside: May 5 to May 19
Start indoors: Mar 31 to Apr 14Transplant outside: May 12 to May 26
Start indoors: Apr 14 to Apr 28Transplant outside: Jun 16 to Jun 30Sow outdoors: Jun 16 to Jun 30
Start indoors: Apr 14 to Apr 28Transplant outside: Jun 2 to Jun 16
Sow outdoors: Apr 14 to May 5Plant for fall: Jun 23 to Jul 14
Sow outdoors: Apr 14 to May 5Plant for fall: Jul 21 to Aug 11
Sow outdoors: Apr 21 to Jun 2Plant for fall: Aug 4 to Aug 25
Start indoors: Apr 28 to May 5Transplant outside: Jun 9 to Jun 16Sow outdoors: Jun 2 to Jun 16
Start indoors: Apr 28 to May 5Sow outdoors: Jun 2 to Jun 16Plant for fall: Jul 7 to Jul 21
Start indoors: Apr 28 to May 5Sow outdoors: Jun 2 to Jun 16
Start indoors: Apr 28 to May 5Transplant outside: Jun 9 to Jun 23
Sow outdoors: May 5 to Jun 2Plant for fall: Jun 23 to Jul 7
Sow outdoors: May 5 to Jun 2Plant for fall: Jul 7 to Jul 21
Sow outdoors: May 5 to May 26
Sow outdoors: May 12 to Jun 9Plant for fall: Jul 7 to Jul 21
Sow outdoors: May 12 to Jun 2Plant for fall: Jul 21 to Aug 11
Sow outdoors: Jun 2 to Jun 23
Sow outdoors: Jun 2 to Jun 16
Transplant outside: Jun 9 to Jun 30
Plant for fall: Sep 1 to Oct 6
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Manhattan, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 3 – Mar 17 | Apr 28 – May 12 | — | — |
| Peppers | Mar 17 – Mar 31 | Jun 9 – Jun 23 | — | — |
| Eggplant | Mar 17 – Mar 31 | Jun 9 – Jun 23 | — | — |
| Tomatoes | Mar 31 – Apr 14 | Jun 2 – Jun 16 | — | — |
| Lettuce | Mar 31 – Apr 14 | May 5 – May 19 | Apr 28 – Jun 2 | Jul 21 – Aug 18 |
| Kale | Mar 31 – Apr 14 | Apr 28 – May 12 | Apr 28 – May 12 | Jul 7 – Jul 28 |
| Broccoli | Mar 31 – Apr 14 | May 12 – May 26 | — | — |
| Cabbage | Mar 31 – Apr 14 | May 5 – May 19 | — | — |
| Cauliflower | Mar 31 – Apr 14 | May 12 – May 26 | — | — |
| Okra | Apr 14 – Apr 28 | Jun 16 – Jun 30 | Jun 16 – Jun 30 | — |
| Basil | Apr 14 – Apr 28 | Jun 2 – Jun 16 | — | — |
| Peas | — | — | Apr 14 – May 5 | Jun 23 – Jul 14 |
| Spinach | — | — | Apr 14 – May 5 | Jul 21 – Aug 11 |
| Radishes | — | — | Apr 21 – Jun 2 | Aug 4 – Aug 25 |
| Cucumbers | Apr 28 – May 5 | Jun 9 – Jun 16 | Jun 2 – Jun 16 | — |
| Zucchini & Summer Squash | Apr 28 – May 5 | — | Jun 2 – Jun 16 | Jul 7 – Jul 21 |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 112 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | Apr 28 – May 5 | — | Jun 2 – Jun 16 | — |
| Melons & Watermelon | Apr 28 – May 5 | Jun 9 – Jun 23 | — | — |
| Carrots | — | — | May 5 – Jun 2 | Jun 23 – Jul 7 |
| Beets | — | — | May 5 – Jun 2 | Jul 7 – Jul 21 |
| Potatoes | — | — | May 5 – May 26 | — |
| Swiss Chard | — | — | May 12 – Jun 9 | Jul 7 – Jul 21 |
| Cilantro | — | — | May 12 – Jun 2 | Jul 21 – Aug 11 |
| Green Beans | — | — | Jun 2 – Jun 23 | — |
| Sweet Corn | — | — | Jun 2 – Jun 16 | — |
| Sweet Potatoes Warning: Your frost-free season is about 112 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 9 – Jun 30 | — | — |
| Garlic | — | — | — | Sep 1 – Oct 6 |
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 Logan Landfill, MT weather station, 11 km away (elevation 4,242 ft (1,293 m)).
Frost dates near Manhattan
- Belgrade May 26 · Sep 16
- Three Forks May 9 · Sep 27
- Willow Creek May 26 · Sep 15
- Bozeman May 26 · Sep 22
- Cardwell May 9 · Sep 27
- Harrison Apr 30 · Oct 10
- Norris Apr 30 · Oct 10
- Toston May 19 · Sep 19
- Pony Apr 30 · Oct 10
- Gallatin Gateway frost any month
Frequently asked questions
When is the last frost in Manhattan, MT?
The median last spring frost in Manhattan, MT is May 26. There is still about a 10% chance of frost after June 12, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Manhattan, MT?
The median first fall frost is September 15, with about a 10% chance of frost before September 1.
How long is the growing season in Manhattan, MT?
About 112 days between the median last spring frost and first fall frost.
What planting zone is Manhattan, MT?
Manhattan, MT is in USDA hardiness zone 5a.