Swanlake, ID frost dates
Last spring frostMay 31median date
First fall frostSep 18median date
Growing season110 daysfrost-free
Hardiness zone5bZone 5b
How Swanlake compares
- In 8 years out of 10, the last spring frost in Swanlake falls between May 13 and June 16, a 34-day window. The first fall frost falls between September 3 and October 5.
- The median last frost is 17 days later than the Idaho median of May 14.
- Its 110-day growing season is longer than 16% of the 244 Idaho places with a regular frost season (state median 138 days).
- The last frost is 30 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 180 nights a year at or below 32°F.
- Compared with Logan, UT, 67 km away, the last frost here is 23 days later than there and the growing season is 37 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 13 |
| 50% (median) | May 31 |
| 10% (safe for tender plants) | June 16 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 3 |
| 50% (median) | September 18 |
| 90% (late) | October 5 |
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 Swanlake, ID
Swanlake, ID frost dates — last frost May 31, first frost Sep 18, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Mar 8 to Mar 22Transplant outside: May 3 to May 17
Start indoors: Mar 22 to Apr 5Transplant outside: Jun 14 to Jun 28
Start indoors: Mar 22 to Apr 5Transplant outside: Jun 14 to Jun 28
Start indoors: Apr 5 to Apr 19Transplant outside: Jun 7 to Jun 21
Start indoors: Apr 5 to Apr 19Transplant outside: May 10 to May 24Sow outdoors: May 3 to Jun 7Plant for fall: Jul 24 to Aug 21
Start indoors: Apr 5 to Apr 19Transplant outside: May 3 to May 17Sow outdoors: May 3 to May 17Plant for fall: Jul 10 to Jul 31
Start indoors: Apr 5 to Apr 19Transplant outside: May 17 to May 31
Start indoors: Apr 5 to Apr 19Transplant outside: May 10 to May 24
Start indoors: Apr 5 to Apr 19Transplant outside: May 17 to May 31
Start indoors: Apr 19 to May 3Transplant outside: Jun 21 to Jul 5Sow outdoors: Jun 21 to Jul 5
Start indoors: Apr 19 to May 3Transplant outside: Jun 7 to Jun 21
Sow outdoors: Apr 19 to May 10Plant for fall: Jun 26 to Jul 17
Sow outdoors: Apr 19 to May 10Plant for fall: Jul 24 to Aug 14
Sow outdoors: Apr 26 to Jun 7Plant for fall: Aug 7 to Aug 28
Start indoors: May 3 to May 10Transplant outside: Jun 14 to Jun 21Sow outdoors: Jun 7 to Jun 21
Start indoors: May 3 to May 10Sow outdoors: Jun 7 to Jun 21Plant for fall: Jul 10 to Jul 24
Start indoors: May 3 to May 10Sow outdoors: Jun 7 to Jun 21
Start indoors: May 3 to May 10Transplant outside: Jun 14 to Jun 28
Sow outdoors: May 10 to Jun 7Plant for fall: Jun 26 to Jul 10
Sow outdoors: May 10 to Jun 7Plant for fall: Jul 10 to Jul 24
Sow outdoors: May 10 to May 31
Sow outdoors: May 17 to Jun 14Plant for fall: Jul 10 to Jul 24
Sow outdoors: May 17 to Jun 7Plant for fall: Jul 24 to Aug 14
Sow outdoors: Jun 7 to Jun 28
Sow outdoors: Jun 7 to Jun 21
Transplant outside: Jun 14 to Jul 5
Plant for fall: Sep 4 to Oct 9
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Swanlake, ID
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 8 – Mar 22 | May 3 – May 17 | — | — |
| Peppers | Mar 22 – Apr 5 | Jun 14 – Jun 28 | — | — |
| Eggplant | Mar 22 – Apr 5 | Jun 14 – Jun 28 | — | — |
| Tomatoes | Apr 5 – Apr 19 | Jun 7 – Jun 21 | — | — |
| Lettuce | Apr 5 – Apr 19 | May 10 – May 24 | May 3 – Jun 7 | Jul 24 – Aug 21 |
| Kale | Apr 5 – Apr 19 | May 3 – May 17 | May 3 – May 17 | Jul 10 – Jul 31 |
| Broccoli | Apr 5 – Apr 19 | May 17 – May 31 | — | — |
| Cabbage | Apr 5 – Apr 19 | May 10 – May 24 | — | — |
| Cauliflower | Apr 5 – Apr 19 | May 17 – May 31 | — | — |
| Okra | Apr 19 – May 3 | Jun 21 – Jul 5 | Jun 21 – Jul 5 | — |
| Basil | Apr 19 – May 3 | Jun 7 – Jun 21 | — | — |
| Peas | — | — | Apr 19 – May 10 | Jun 26 – Jul 17 |
| Spinach | — | — | Apr 19 – May 10 | Jul 24 – Aug 14 |
| Radishes | — | — | Apr 26 – Jun 7 | Aug 7 – Aug 28 |
| Cucumbers | May 3 – May 10 | Jun 14 – Jun 21 | Jun 7 – Jun 21 | — |
| Zucchini & Summer Squash | May 3 – May 10 | — | Jun 7 – Jun 21 | Jul 10 – Jul 24 |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 110 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 3 – May 10 | — | Jun 7 – Jun 21 | — |
| Melons & Watermelon | May 3 – May 10 | Jun 14 – Jun 28 | — | — |
| Carrots | — | — | May 10 – Jun 7 | Jun 26 – Jul 10 |
| Beets | — | — | May 10 – Jun 7 | Jul 10 – Jul 24 |
| Potatoes | — | — | May 10 – May 31 | — |
| Swiss Chard | — | — | May 17 – Jun 14 | Jul 10 – Jul 24 |
| Cilantro | — | — | May 17 – Jun 7 | Jul 24 – Aug 14 |
| Green Beans | — | — | Jun 7 – Jun 28 | — |
| Sweet Corn | — | — | Jun 7 – Jun 21 | — |
| Sweet Potatoes Warning: Your frost-free season is about 110 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 14 – Jul 5 | — | — |
| Garlic | — | — | — | Sep 4 – Oct 9 |
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 Downey, ID weather station, 17 km away (elevation 4,865 ft (1,483 m)).
Frost dates near Swanlake
- Clifton May 16 · Sep 28
- Downey May 31 · Sep 18
- Dayton May 16 · Sep 28
- Thatcher May 29 · Sep 17
- Preston May 16 · Sep 28
- Malad City May 22 · Sep 20
- Weston May 16 · Sep 28
- Arimo May 23 · Sep 24
- Grace May 29 · Sep 17
- Lava Hot Springs May 21 · Sep 21
Frequently asked questions
When is the last frost in Swanlake, ID?
The median last spring frost in Swanlake, ID is May 31. There is still about a 10% chance of frost after June 16, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Swanlake, ID?
The median first fall frost is September 18, with about a 10% chance of frost before September 3.
How long is the growing season in Swanlake, ID?
About 110 days between the median last spring frost and first fall frost.
What planting zone is Swanlake, ID?
Swanlake, ID is in USDA hardiness zone 5b.