O Brien, OR frost dates
Last spring frostMay 1median date
First fall frostOct 12median date
Growing season164 daysfrost-free
Hardiness zone8bZone 8b
How O Brien compares
- In 8 years out of 10, the last spring frost in O Brien falls between April 14 and May 23, a 39-day window. The first fall frost falls between September 23 and November 2.
- The median last frost is 15 days later than the Oregon median of Apr 16.
- Its 164-day growing season is longer than 31% of the 345 Oregon places with a regular frost season (state median 193 days).
- The last frost is 46 days later than the zone 8b median of Mar 16. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 8b chart.
- The weather station records an average of 75 nights a year at or below 32°F.
- Compared with Medford, OR, 72 km away, the last frost here is 23 days later than there and the growing season is 40 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 14 |
| 50% (median) | May 1 |
| 10% (safe for tender plants) | May 23 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 23 |
| 50% (median) | October 12 |
| 90% (late) | November 2 |
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 O Brien, OR
O Brien, OR frost dates — last frost May 1, first frost Oct 12, zone 8b. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Feb 6 to Feb 20Transplant outside: Apr 3 to Apr 17
Start indoors: Feb 20 to Mar 6Transplant outside: May 15 to May 29
Start indoors: Feb 20 to Mar 6Transplant outside: May 15 to May 29
Start indoors: Mar 6 to Mar 20Transplant outside: May 8 to May 22
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 10 to Apr 24Sow outdoors: Apr 3 to May 8Plant for fall: Aug 17 to Sep 14
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 3 to Apr 17Sow outdoors: Apr 3 to Apr 17Plant for fall: Aug 3 to Aug 24
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 17 to May 1Plant for fall: Jul 6 to Jul 27
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 10 to Apr 24Plant for fall: Jul 6 to Jul 27
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 17 to May 1Plant for fall: Jul 6 to Jul 27
Start indoors: Mar 20 to Apr 3Transplant outside: May 22 to Jun 5Sow outdoors: May 22 to Jun 5
Start indoors: Mar 20 to Apr 3Transplant outside: May 8 to May 22
Sow outdoors: Mar 20 to Apr 10Plant for fall: Jul 20 to Aug 10
Sow outdoors: Mar 20 to Apr 10Plant for fall: Aug 17 to Sep 7
Sow outdoors: Mar 27 to May 8Plant for fall: Aug 31 to Sep 21
Start indoors: Apr 3 to Apr 10Transplant outside: May 15 to May 22Sow outdoors: May 8 to May 22Plant for fall: Jul 27 to Aug 10
Start indoors: Apr 3 to Apr 10Sow outdoors: May 8 to May 22Plant for fall: Aug 3 to Aug 17
Start indoors: Apr 3 to Apr 10Sow outdoors: May 8 to May 22
Start indoors: Apr 3 to Apr 10Transplant outside: May 15 to May 29
Sow outdoors: Apr 10 to May 8Plant for fall: Jul 20 to Aug 3
Sow outdoors: Apr 10 to May 8Plant for fall: Aug 3 to Aug 17
Sow outdoors: Apr 10 to May 1
Sow outdoors: Apr 17 to May 15Plant for fall: Aug 3 to Aug 17
Sow outdoors: Apr 17 to May 8Plant for fall: Aug 17 to Sep 7
Sow outdoors: May 8 to May 29Plant for fall: Jul 27 to Aug 10
Sow outdoors: May 8 to May 22
Transplant outside: May 15 to Jun 5
Plant for fall: Sep 28 to Nov 2
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in O Brien, OR
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 6 – Feb 20 | Apr 3 – Apr 17 | — | — |
| Peppers | Feb 20 – Mar 6 | May 15 – May 29 | — | — |
| Eggplant | Feb 20 – Mar 6 | May 15 – May 29 | — | — |
| Tomatoes | Mar 6 – Mar 20 | May 8 – May 22 | — | — |
| Lettuce | Mar 6 – Mar 20 | Apr 10 – Apr 24 | Apr 3 – May 8 | Aug 17 – Sep 14 |
| Kale | Mar 6 – Mar 20 | Apr 3 – Apr 17 | Apr 3 – Apr 17 | Aug 3 – Aug 24 |
| Broccoli | Mar 6 – Mar 20 | Apr 17 – May 1 | — | Jul 6 – Jul 27 |
| Cabbage | Mar 6 – Mar 20 | Apr 10 – Apr 24 | — | Jul 6 – Jul 27 |
| Cauliflower | Mar 6 – Mar 20 | Apr 17 – May 1 | — | Jul 6 – Jul 27 |
| Okra | Mar 20 – Apr 3 | May 22 – Jun 5 | May 22 – Jun 5 | — |
| Basil | Mar 20 – Apr 3 | May 8 – May 22 | — | — |
| Peas | — | — | Mar 20 – Apr 10 | Jul 20 – Aug 10 |
| Spinach | — | — | Mar 20 – Apr 10 | Aug 17 – Sep 7 |
| Radishes | — | — | Mar 27 – May 8 | Aug 31 – Sep 21 |
| Cucumbers | Apr 3 – Apr 10 | May 15 – May 22 | May 8 – May 22 | Jul 27 – Aug 10 |
| Zucchini & Summer Squash | Apr 3 – Apr 10 | — | May 8 – May 22 | Aug 3 – Aug 17 |
| Winter Squash & Pumpkins | Apr 3 – Apr 10 | — | May 8 – May 22 | — |
| Melons & Watermelon | Apr 3 – Apr 10 | May 15 – May 29 | — | — |
| Carrots | — | — | Apr 10 – May 8 | Jul 20 – Aug 3 |
| Beets | — | — | Apr 10 – May 8 | Aug 3 – Aug 17 |
| Potatoes | — | — | Apr 10 – May 1 | — |
| Swiss Chard | — | — | Apr 17 – May 15 | Aug 3 – Aug 17 |
| Cilantro | — | — | Apr 17 – May 8 | Aug 17 – Sep 7 |
| Green Beans | — | — | May 8 – May 29 | Jul 27 – Aug 10 |
| Sweet Corn | — | — | May 8 – May 22 | — |
| Sweet Potatoes | — | May 15 – Jun 5 | — | — |
| Garlic | — | — | — | Sep 28 – Nov 2 |
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 Cave Junction 1 Wnw, OR weather station, 9 km away (elevation 1,378 ft (420 m)).
Frost dates near O Brien
- Cave Junction May 1 · Oct 12
- Kerby May 1 · Oct 12
- Selma May 1 · Oct 12
- Wilderville Apr 8 · Oct 28
- Williams May 4 · Oct 13
- Murphy Apr 8 · Oct 28
- Grants Pass Apr 8 · Oct 28
- Brookings Jan 31 · Dec 27
- Merlin May 16 · Oct 30
- Jacksonville May 4 · Oct 13
Frequently asked questions
When is the last frost in O Brien, OR?
The median last spring frost in O Brien, OR is May 1. There is still about a 10% chance of frost after May 23, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in O Brien, OR?
The median first fall frost is October 12, with about a 10% chance of frost before September 23.
How long is the growing season in O Brien, OR?
About 164 days between the median last spring frost and first fall frost.
What planting zone is O Brien, OR?
O Brien, OR is in USDA hardiness zone 8b.