New Plymouth, ID frost dates
Last spring frostApr 22median date
First fall frostOct 9median date
Growing season170 daysfrost-free
Hardiness zone7aZone 7a
How New Plymouth compares
- In 8 years out of 10, the last spring frost in New Plymouth falls between April 7 and May 7, a 30-day window. The first fall frost falls between September 26 and October 23.
- The median last frost is 22 days earlier than the Idaho median of May 14.
- Its 170-day growing season is longer than 87% of the 244 Idaho places with a regular frost season (state median 138 days).
- The last frost is 6 days later than the zone 7a median of Apr 16. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 7a chart.
- The weather station records an average of 150 nights a year at or below 32°F.
- Compared with Caldwell, ID, 33 km away, the last frost here is 1 day earlier than there and the growing season is 8 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 7 |
| 50% (median) | April 22 |
| 10% (safe for tender plants) | May 7 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 26 |
| 50% (median) | October 9 |
| 90% (late) | October 23 |
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 New Plymouth, ID
New Plymouth, ID frost dates — last frost Apr 22, first frost Oct 9, zone 7a. whenisthelastfrost.com
Crop
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Start indoors: Jan 28 to Feb 11Transplant outside: Mar 25 to Apr 8
Start indoors: Feb 11 to Feb 25Transplant outside: May 6 to May 20
Start indoors: Feb 11 to Feb 25Transplant outside: May 6 to May 20
Start indoors: Feb 25 to Mar 11Transplant outside: Apr 29 to May 13
Start indoors: Feb 25 to Mar 11Transplant outside: Apr 1 to Apr 15Sow outdoors: Mar 25 to Apr 29Plant for fall: Aug 14 to Sep 11
Start indoors: Feb 25 to Mar 11Transplant outside: Mar 25 to Apr 8Sow outdoors: Mar 25 to Apr 8Plant for fall: Jul 31 to Aug 21
Start indoors: Feb 25 to Mar 11Transplant outside: Apr 8 to Apr 22Plant for fall: Jul 3 to Jul 24
Start indoors: Feb 25 to Mar 11Transplant outside: Apr 1 to Apr 15Plant for fall: Jul 3 to Jul 24
Start indoors: Feb 25 to Mar 11Transplant outside: Apr 8 to Apr 22Plant for fall: Jul 3 to Jul 24
Start indoors: Mar 11 to Mar 25Transplant outside: May 13 to May 27Sow outdoors: May 13 to May 27
Start indoors: Mar 11 to Mar 25Transplant outside: Apr 29 to May 13
Sow outdoors: Mar 11 to Apr 1Plant for fall: Jul 17 to Aug 7
Sow outdoors: Mar 11 to Apr 1Plant for fall: Aug 14 to Sep 4
Sow outdoors: Mar 18 to Apr 29Plant for fall: Aug 28 to Sep 18
Start indoors: Mar 25 to Apr 1Transplant outside: May 6 to May 13Sow outdoors: Apr 29 to May 13Plant for fall: Jul 24 to Aug 7
Start indoors: Mar 25 to Apr 1Sow outdoors: Apr 29 to May 13Plant for fall: Jul 31 to Aug 14
Start indoors: Mar 25 to Apr 1Sow outdoors: Apr 29 to May 13
Start indoors: Mar 25 to Apr 1Transplant outside: May 6 to May 20
Sow outdoors: Apr 1 to Apr 29Plant for fall: Jul 17 to Jul 31
Sow outdoors: Apr 1 to Apr 29Plant for fall: Jul 31 to Aug 14
Sow outdoors: Apr 1 to Apr 22
Sow outdoors: Apr 8 to May 6Plant for fall: Jul 31 to Aug 14
Sow outdoors: Apr 8 to Apr 29Plant for fall: Aug 14 to Sep 4
Sow outdoors: Apr 29 to May 20Plant for fall: Jul 24 to Aug 7
Sow outdoors: Apr 29 to May 13
Transplant outside: May 6 to May 27
Plant for fall: Sep 25 to Oct 30
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in New Plymouth, ID
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 28 – Feb 11 | Mar 25 – Apr 8 | — | — |
| Peppers | Feb 11 – Feb 25 | May 6 – May 20 | — | — |
| Eggplant | Feb 11 – Feb 25 | May 6 – May 20 | — | — |
| Tomatoes | Feb 25 – Mar 11 | Apr 29 – May 13 | — | — |
| Lettuce | Feb 25 – Mar 11 | Apr 1 – Apr 15 | Mar 25 – Apr 29 | Aug 14 – Sep 11 |
| Kale | Feb 25 – Mar 11 | Mar 25 – Apr 8 | Mar 25 – Apr 8 | Jul 31 – Aug 21 |
| Broccoli | Feb 25 – Mar 11 | Apr 8 – Apr 22 | — | Jul 3 – Jul 24 |
| Cabbage | Feb 25 – Mar 11 | Apr 1 – Apr 15 | — | Jul 3 – Jul 24 |
| Cauliflower | Feb 25 – Mar 11 | Apr 8 – Apr 22 | — | Jul 3 – Jul 24 |
| Okra | Mar 11 – Mar 25 | May 13 – May 27 | May 13 – May 27 | — |
| Basil | Mar 11 – Mar 25 | Apr 29 – May 13 | — | — |
| Peas | — | — | Mar 11 – Apr 1 | Jul 17 – Aug 7 |
| Spinach | — | — | Mar 11 – Apr 1 | Aug 14 – Sep 4 |
| Radishes | — | — | Mar 18 – Apr 29 | Aug 28 – Sep 18 |
| Cucumbers | Mar 25 – Apr 1 | May 6 – May 13 | Apr 29 – May 13 | Jul 24 – Aug 7 |
| Zucchini & Summer Squash | Mar 25 – Apr 1 | — | Apr 29 – May 13 | Jul 31 – Aug 14 |
| Winter Squash & Pumpkins | Mar 25 – Apr 1 | — | Apr 29 – May 13 | — |
| Melons & Watermelon | Mar 25 – Apr 1 | May 6 – May 20 | — | — |
| Carrots | — | — | Apr 1 – Apr 29 | Jul 17 – Jul 31 |
| Beets | — | — | Apr 1 – Apr 29 | Jul 31 – Aug 14 |
| Potatoes | — | — | Apr 1 – Apr 22 | — |
| Swiss Chard | — | — | Apr 8 – May 6 | Jul 31 – Aug 14 |
| Cilantro | — | — | Apr 8 – Apr 29 | Aug 14 – Sep 4 |
| Green Beans | — | — | Apr 29 – May 20 | Jul 24 – Aug 7 |
| Sweet Corn | — | — | Apr 29 – May 13 | — |
| Sweet Potatoes | — | May 6 – May 27 | — | — |
| Garlic | — | — | — | Sep 25 – Oct 30 |
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 Ontario Ksrv, OR weather station, 16 km away (elevation 2,146 ft (654 m)).
Frost dates near New Plymouth
- Fruitland Apr 22 · Oct 9
- Letha Apr 30 · Oct 17
- Payette Apr 19 · Oct 20
- Parma Apr 27 · Oct 9
- Emmett Apr 30 · Oct 17
- Notus Apr 27 · Oct 9
- Middleton Apr 29 · Oct 13
- Greenleaf Apr 24 · Oct 9
- Caldwell Apr 23 · Oct 18
- Wilder Apr 24 · Oct 9
Frequently asked questions
When is the last frost in New Plymouth, ID?
The median last spring frost in New Plymouth, ID is April 22. There is still about a 10% chance of frost after May 7, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in New Plymouth, ID?
The median first fall frost is October 9, with about a 10% chance of frost before September 26.
How long is the growing season in New Plymouth, ID?
About 170 days between the median last spring frost and first fall frost.
What planting zone is New Plymouth, ID?
New Plymouth, ID is in USDA hardiness zone 7a.