Basalt, ID frost dates
Last spring frostMay 5median date
First fall frostOct 3median date
Growing season151 daysfrost-free
Hardiness zone5bZone 5b
How Basalt compares
- In 8 years out of 10, the last spring frost in Basalt falls between April 23 and May 22, a 29-day window. The first fall frost falls between September 16 and October 18.
- The median last frost is 9 days earlier than the Idaho median of May 14.
- Its 151-day growing season is longer than 68% of the 244 Idaho places with a regular frost season (state median 138 days).
- The last frost is 4 days later than the zone 5b median of May 1. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5b chart.
- The weather station records an average of 162 nights a year at or below 32°F.
- Compared with Idaho Falls, ID, 23 km away, the last frost here is 4 days earlier than there and the growing season is 6 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 23 |
| 50% (median) | May 5 |
| 10% (safe for tender plants) | May 22 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 16 |
| 50% (median) | October 3 |
| 90% (late) | October 18 |
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 Basalt, ID
Basalt, ID frost dates — last frost May 5, first frost Oct 3, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Feb 10 to Feb 24Transplant outside: Apr 7 to Apr 21
Start indoors: Feb 24 to Mar 10Transplant outside: May 19 to Jun 2
Start indoors: Feb 24 to Mar 10Transplant outside: May 19 to Jun 2
Start indoors: Mar 10 to Mar 24Transplant outside: May 12 to May 26
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 14 to Apr 28Sow outdoors: Apr 7 to May 12Plant for fall: Aug 8 to Sep 5
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 7 to Apr 21Sow outdoors: Apr 7 to Apr 21Plant for fall: Jul 25 to Aug 15
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 21 to May 5Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 14 to Apr 28Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 21 to May 5Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 24 to Apr 7Transplant outside: May 26 to Jun 9Sow outdoors: May 26 to Jun 9
Start indoors: Mar 24 to Apr 7Transplant outside: May 12 to May 26
Sow outdoors: Mar 24 to Apr 14Plant for fall: Jul 11 to Aug 1
Sow outdoors: Mar 24 to Apr 14Plant for fall: Aug 8 to Aug 29
Sow outdoors: Mar 31 to May 12Plant for fall: Aug 22 to Sep 12
Start indoors: Apr 7 to Apr 14Transplant outside: May 19 to May 26Sow outdoors: May 12 to May 26Plant for fall: Jul 18 to Aug 1
Start indoors: Apr 7 to Apr 14Sow outdoors: May 12 to May 26Plant for fall: Jul 25 to Aug 8
Start indoors: Apr 7 to Apr 14Sow outdoors: May 12 to May 26
Start indoors: Apr 7 to Apr 14Transplant outside: May 19 to Jun 2
Sow outdoors: Apr 14 to May 12Plant for fall: Jul 11 to Jul 25
Sow outdoors: Apr 14 to May 12Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 14 to May 5
Sow outdoors: Apr 21 to May 19Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 21 to May 12Plant for fall: Aug 8 to Aug 29
Sow outdoors: May 12 to Jun 2Plant for fall: Jul 18 to Aug 1
Sow outdoors: May 12 to May 26
Transplant outside: May 19 to Jun 9
Plant for fall: Sep 19 to Oct 24
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Basalt, ID
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 10 – Feb 24 | Apr 7 – Apr 21 | — | — |
| Peppers | Feb 24 – Mar 10 | May 19 – Jun 2 | — | — |
| Eggplant | Feb 24 – Mar 10 | May 19 – Jun 2 | — | — |
| Tomatoes | Mar 10 – Mar 24 | May 12 – May 26 | — | — |
| Lettuce | Mar 10 – Mar 24 | Apr 14 – Apr 28 | Apr 7 – May 12 | Aug 8 – Sep 5 |
| Kale | Mar 10 – Mar 24 | Apr 7 – Apr 21 | Apr 7 – Apr 21 | Jul 25 – Aug 15 |
| Broccoli | Mar 10 – Mar 24 | Apr 21 – May 5 | — | Jun 27 – Jul 18 |
| Cabbage | Mar 10 – Mar 24 | Apr 14 – Apr 28 | — | Jun 27 – Jul 18 |
| Cauliflower | Mar 10 – Mar 24 | Apr 21 – May 5 | — | Jun 27 – Jul 18 |
| Okra | Mar 24 – Apr 7 | May 26 – Jun 9 | May 26 – Jun 9 | — |
| Basil | Mar 24 – Apr 7 | May 12 – May 26 | — | — |
| Peas | — | — | Mar 24 – Apr 14 | Jul 11 – Aug 1 |
| Spinach | — | — | Mar 24 – Apr 14 | Aug 8 – Aug 29 |
| Radishes | — | — | Mar 31 – May 12 | Aug 22 – Sep 12 |
| Cucumbers | Apr 7 – Apr 14 | May 19 – May 26 | May 12 – May 26 | Jul 18 – Aug 1 |
| Zucchini & Summer Squash | Apr 7 – Apr 14 | — | May 12 – May 26 | Jul 25 – Aug 8 |
| Winter Squash & Pumpkins | Apr 7 – Apr 14 | — | May 12 – May 26 | — |
| Melons & Watermelon | Apr 7 – Apr 14 | May 19 – Jun 2 | — | — |
| Carrots | — | — | Apr 14 – May 12 | Jul 11 – Jul 25 |
| Beets | — | — | Apr 14 – May 12 | Jul 25 – Aug 8 |
| Potatoes | — | — | Apr 14 – May 5 | — |
| Swiss Chard | — | — | Apr 21 – May 19 | Jul 25 – Aug 8 |
| Cilantro | — | — | Apr 21 – May 12 | Aug 8 – Aug 29 |
| Green Beans | — | — | May 12 – Jun 2 | Jul 18 – Aug 1 |
| Sweet Corn | — | — | May 12 – May 26 | — |
| Sweet Potatoes | — | May 19 – Jun 9 | — | — |
| Garlic | — | — | — | Sep 19 – Oct 24 |
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 Blackfoot Fire Dept, ID weather station, 20 km away (elevation 4,498 ft (1,371 m)).
Frost dates near Basalt
- Firth May 5 · Oct 3
- Shelley May 23 · Sep 20
- Blackfoot May 5 · Oct 3
- Idaho Falls May 9 · Oct 1
- Moreland May 5 · Oct 3
- Iona May 9 · Oct 1
- Ucon May 9 · Oct 5
- Fort Hall May 20 · Sep 20
- Lewisville May 9 · Oct 5
- Pingree May 20 · Sep 20
Frequently asked questions
When is the last frost in Basalt, ID?
The median last spring frost in Basalt, ID is May 5. There is still about a 10% chance of frost after May 22, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Basalt, ID?
The median first fall frost is October 3, with about a 10% chance of frost before September 16.
How long is the growing season in Basalt, ID?
About 151 days between the median last spring frost and first fall frost.
What planting zone is Basalt, ID?
Basalt, ID is in USDA hardiness zone 5b.