Irrigon, OR frost dates
Last spring frostApr 14median date
First fall frostOct 21median date
Growing season190 daysfrost-free
Hardiness zone7bZone 7b
How Irrigon compares
- In 8 years out of 10, the last spring frost in Irrigon falls between March 28 and May 2, a 35-day window. The first fall frost falls between October 5 and November 4.
- The median last frost is 2 days earlier than the Oregon median of Apr 16.
- Its 190-day growing season is longer than 45% of the 345 Oregon places with a regular frost season (state median 193 days).
- The last frost is 9 days later than the zone 7b median of Apr 5. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 7b chart.
- The weather station records an average of 104 nights a year at or below 32°F.
- Compared with Kennewick, WA, 41 km away, the last frost here is 17 days later than there and the growing season is 26 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | March 28 |
| 50% (median) | April 14 |
| 10% (safe for tender plants) | May 2 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 5 |
| 50% (median) | October 21 |
| 90% (late) | November 4 |
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 Irrigon, OR
Irrigon, OR frost dates — last frost Apr 14, first frost Oct 21, zone 7b. whenisthelastfrost.com
Crop
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Start indoors: Jan 20 to Feb 3Transplant outside: Mar 17 to Mar 31
Start indoors: Feb 3 to Feb 17Transplant outside: Apr 28 to May 12
Start indoors: Feb 3 to Feb 17Transplant outside: Apr 28 to May 12
Start indoors: Feb 17 to Mar 3Transplant outside: Apr 21 to May 5
Start indoors: Feb 17 to Mar 3Transplant outside: Mar 24 to Apr 7Sow outdoors: Mar 17 to Apr 21Plant for fall: Aug 26 to Sep 23
Start indoors: Feb 17 to Mar 3Transplant outside: Mar 17 to Mar 31Sow outdoors: Mar 17 to Mar 31Plant for fall: Aug 12 to Sep 2
Start indoors: Feb 17 to Mar 3Transplant outside: Mar 31 to Apr 14Plant for fall: Jul 15 to Aug 5
Start indoors: Feb 17 to Mar 3Transplant outside: Mar 24 to Apr 7Plant for fall: Jul 15 to Aug 5
Start indoors: Feb 17 to Mar 3Transplant outside: Mar 31 to Apr 14Plant for fall: Jul 15 to Aug 5
Start indoors: Mar 3 to Mar 17Transplant outside: May 5 to May 19Sow outdoors: May 5 to May 19
Start indoors: Mar 3 to Mar 17Transplant outside: Apr 21 to May 5
Sow outdoors: Mar 3 to Mar 24Plant for fall: Jul 29 to Aug 19
Sow outdoors: Mar 3 to Mar 24Plant for fall: Aug 26 to Sep 16
Sow outdoors: Mar 10 to Apr 21Plant for fall: Sep 9 to Sep 30
Start indoors: Mar 17 to Mar 24Transplant outside: Apr 28 to May 5Sow outdoors: Apr 21 to May 5Plant for fall: Aug 5 to Aug 19
Start indoors: Mar 17 to Mar 24Sow outdoors: Apr 21 to May 5Plant for fall: Aug 12 to Aug 26
Start indoors: Mar 17 to Mar 24Sow outdoors: Apr 21 to May 5
Start indoors: Mar 17 to Mar 24Transplant outside: Apr 28 to May 12
Sow outdoors: Mar 24 to Apr 21Plant for fall: Jul 29 to Aug 12
Sow outdoors: Mar 24 to Apr 21Plant for fall: Aug 12 to Aug 26
Sow outdoors: Mar 24 to Apr 14
Sow outdoors: Mar 31 to Apr 28Plant for fall: Aug 12 to Aug 26
Sow outdoors: Mar 31 to Apr 21Plant for fall: Aug 26 to Sep 16
Sow outdoors: Apr 21 to May 12Plant for fall: Aug 5 to Aug 19
Sow outdoors: Apr 21 to May 5
Transplant outside: Apr 28 to May 19
Plant for fall: Oct 7 to Nov 11
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Irrigon, OR
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 20 – Feb 3 | Mar 17 – Mar 31 | — | — |
| Peppers | Feb 3 – Feb 17 | Apr 28 – May 12 | — | — |
| Eggplant | Feb 3 – Feb 17 | Apr 28 – May 12 | — | — |
| Tomatoes | Feb 17 – Mar 3 | Apr 21 – May 5 | — | — |
| Lettuce | Feb 17 – Mar 3 | Mar 24 – Apr 7 | Mar 17 – Apr 21 | Aug 26 – Sep 23 |
| Kale | Feb 17 – Mar 3 | Mar 17 – Mar 31 | Mar 17 – Mar 31 | Aug 12 – Sep 2 |
| Broccoli | Feb 17 – Mar 3 | Mar 31 – Apr 14 | — | Jul 15 – Aug 5 |
| Cabbage | Feb 17 – Mar 3 | Mar 24 – Apr 7 | — | Jul 15 – Aug 5 |
| Cauliflower | Feb 17 – Mar 3 | Mar 31 – Apr 14 | — | Jul 15 – Aug 5 |
| Okra | Mar 3 – Mar 17 | May 5 – May 19 | May 5 – May 19 | — |
| Basil | Mar 3 – Mar 17 | Apr 21 – May 5 | — | — |
| Peas | — | — | Mar 3 – Mar 24 | Jul 29 – Aug 19 |
| Spinach | — | — | Mar 3 – Mar 24 | Aug 26 – Sep 16 |
| Radishes | — | — | Mar 10 – Apr 21 | Sep 9 – Sep 30 |
| Cucumbers | Mar 17 – Mar 24 | Apr 28 – May 5 | Apr 21 – May 5 | Aug 5 – Aug 19 |
| Zucchini & Summer Squash | Mar 17 – Mar 24 | — | Apr 21 – May 5 | Aug 12 – Aug 26 |
| Winter Squash & Pumpkins | Mar 17 – Mar 24 | — | Apr 21 – May 5 | — |
| Melons & Watermelon | Mar 17 – Mar 24 | Apr 28 – May 12 | — | — |
| Carrots | — | — | Mar 24 – Apr 21 | Jul 29 – Aug 12 |
| Beets | — | — | Mar 24 – Apr 21 | Aug 12 – Aug 26 |
| Potatoes | — | — | Mar 24 – Apr 14 | — |
| Swiss Chard | — | — | Mar 31 – Apr 28 | Aug 12 – Aug 26 |
| Cilantro | — | — | Mar 31 – Apr 21 | Aug 26 – Sep 16 |
| Green Beans | — | — | Apr 21 – May 12 | Aug 5 – Aug 19 |
| Sweet Corn | — | — | Apr 21 – May 5 | — |
| Sweet Potatoes | — | Apr 28 – May 19 | — | — |
| Garlic | — | — | — | Oct 7 – Nov 11 |
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 Boardman, OR weather station, 15 km away (elevation 279 ft (85 m)).
Frost dates near Irrigon
- Umatilla Apr 27 · Oct 7
- Hermiston Apr 27 · Oct 7
- Boardman Apr 14 · Oct 21
- Stanfield Apr 26 · Oct 10
- Echo Apr 26 · Oct 10
- Ione Apr 26 · Oct 19
- Lexington Apr 26 · Oct 19
- Arlington Apr 6 · Oct 21
- Heppner Apr 26 · Oct 19
- Helix May 12 · Sep 27
Frequently asked questions
When is the last frost in Irrigon, OR?
The median last spring frost in Irrigon, OR is April 14. There is still about a 10% chance of frost after May 2, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Irrigon, OR?
The median first fall frost is October 21, with about a 10% chance of frost before October 5.
How long is the growing season in Irrigon, OR?
About 190 days between the median last spring frost and first fall frost.
What planting zone is Irrigon, OR?
Irrigon, OR is in USDA hardiness zone 7b.