Riverside, OR frost dates
Last spring frostJun 7median date
First fall frostSep 6median date
Growing season91 daysfrost-free
Hardiness zone6aZone 6a
How Riverside compares
- In 8 years out of 10, the last spring frost in Riverside falls between May 21 and June 28, a 38-day window. The first fall frost falls between August 22 and September 22.
- The median last frost is 52 days later than the Oregon median of Apr 16.
- Its 91-day growing season is among the shortest of the 345 Oregon places with a regular frost season.
- The last frost is 39 days later than the zone 6a median of Apr 29. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6a chart.
- The weather station records an average of 195 nights a year at or below 32°F.
- Compared with Caldwell, ID, 110 km away, the last frost here is 45 days later than there and the growing season is 87 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 21 |
| 50% (median) | June 7 |
| 10% (safe for tender plants) | June 28 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | August 22 |
| 50% (median) | September 6 |
| 90% (late) | September 22 |
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 Riverside, OR
Riverside, OR frost dates — last frost Jun 7, first frost Sep 6, zone 6a. whenisthelastfrost.com
Crop
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Start indoors: Mar 15 to Mar 29Transplant outside: May 10 to May 24
Start indoors: Mar 29 to Apr 12Transplant outside: Jun 21 to Jul 5
Start indoors: Mar 29 to Apr 12Transplant outside: Jun 21 to Jul 5
Start indoors: Apr 12 to Apr 26Transplant outside: Jun 14 to Jun 28
Start indoors: Apr 12 to Apr 26Transplant outside: May 17 to May 31Sow outdoors: May 10 to Jun 14Plant for fall: Jul 12 to Aug 9
Start indoors: Apr 12 to Apr 26Transplant outside: May 10 to May 24Sow outdoors: May 10 to May 24Plant for fall: Jun 28 to Jul 19
Start indoors: Apr 12 to Apr 26Transplant outside: May 24 to Jun 7
Start indoors: Apr 12 to Apr 26Transplant outside: May 17 to May 31
Start indoors: Apr 12 to Apr 26Transplant outside: May 24 to Jun 7
Start indoors: Apr 26 to May 10Transplant outside: Jun 28 to Jul 12Sow outdoors: Jun 28 to Jul 12
Start indoors: Apr 26 to May 10Transplant outside: Jun 14 to Jun 28
Sow outdoors: Apr 26 to May 17
Sow outdoors: Apr 26 to May 17Plant for fall: Jul 12 to Aug 2
Sow outdoors: May 3 to Jun 14Plant for fall: Jul 26 to Aug 16
Start indoors: May 10 to May 17Transplant outside: Jun 21 to Jun 28Sow outdoors: Jun 14 to Jun 28
Start indoors: May 10 to May 17Sow outdoors: Jun 14 to Jun 28
Start indoors: May 10 to May 17Sow outdoors: Jun 14 to Jun 28
Start indoors: May 10 to May 17Transplant outside: Jun 21 to Jul 5
Sow outdoors: May 17 to Jun 14
Sow outdoors: May 17 to Jun 14
Sow outdoors: May 17 to Jun 7
Sow outdoors: May 24 to Jun 21
Sow outdoors: May 24 to Jun 14Plant for fall: Jul 12 to Aug 2
Sow outdoors: Jun 14 to Jul 5
Sow outdoors: Jun 14 to Jun 28
Transplant outside: Jun 21 to Jul 12
Plant for fall: Aug 23 to Sep 27
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Riverside, OR
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 15 – Mar 29 | May 10 – May 24 | — | — |
| Peppers | Mar 29 – Apr 12 | Jun 21 – Jul 5 | — | — |
| Eggplant | Mar 29 – Apr 12 | Jun 21 – Jul 5 | — | — |
| Tomatoes | Apr 12 – Apr 26 | Jun 14 – Jun 28 | — | — |
| Lettuce | Apr 12 – Apr 26 | May 17 – May 31 | May 10 – Jun 14 | Jul 12 – Aug 9 |
| Kale | Apr 12 – Apr 26 | May 10 – May 24 | May 10 – May 24 | Jun 28 – Jul 19 |
| Broccoli | Apr 12 – Apr 26 | May 24 – Jun 7 | — | — |
| Cabbage | Apr 12 – Apr 26 | May 17 – May 31 | — | — |
| Cauliflower | Apr 12 – Apr 26 | May 24 – Jun 7 | — | — |
| Okra | Apr 26 – May 10 | Jun 28 – Jul 12 | Jun 28 – Jul 12 | — |
| Basil | Apr 26 – May 10 | Jun 14 – Jun 28 | — | — |
| Peas | — | — | Apr 26 – May 17 | — |
| Spinach | — | — | Apr 26 – May 17 | Jul 12 – Aug 2 |
| Radishes | — | — | May 3 – Jun 14 | Jul 26 – Aug 16 |
| Cucumbers | May 10 – May 17 | Jun 21 – Jun 28 | Jun 14 – Jun 28 | — |
| Zucchini & Summer Squash | May 10 – May 17 | — | Jun 14 – Jun 28 | — |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 91 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 10 – May 17 | — | Jun 14 – Jun 28 | — |
| Melons & Watermelon Warning: Your frost-free season is about 91 days, which is tight for melons & watermelon (85+ days). Choose early varieties and use transplants or row covers. | May 10 – May 17 | Jun 21 – Jul 5 | — | — |
| Carrots | — | — | May 17 – Jun 14 | — |
| Beets | — | — | May 17 – Jun 14 | — |
| Potatoes | — | — | May 17 – Jun 7 | — |
| Swiss Chard | — | — | May 24 – Jun 21 | — |
| Cilantro | — | — | May 24 – Jun 14 | Jul 12 – Aug 2 |
| Green Beans | — | — | Jun 14 – Jul 5 | — |
| Sweet Corn Warning: Your frost-free season is about 91 days, which is tight for sweet corn (80+ days). Choose early varieties and use transplants or row covers. | — | — | Jun 14 – Jun 28 | — |
| Sweet Potatoes Warning: Your frost-free season is about 91 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 21 – Jul 12 | — | — |
| Garlic | — | — | — | Aug 23 – Sep 27 |
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 Riverside 7 Ssw, OR weather station, 12 km away (elevation 3,379 ft (1,030 m)).
Frost dates near Riverside
- Crane Jun 7 · Sep 6
- Juntura Jun 5 · Sep 5
- Drewsey Jun 5 · Sep 5
- Harper May 7 · Oct 3
- Westfall May 7 · Oct 3
- Burns Jun 11 · Sep 6
- Diamond May 29 · Sep 18
- Hines Jun 11 · Sep 6
- Arock Jun 11 · Sep 10
- Adrian Apr 24 · Oct 9
Frequently asked questions
When is the last frost in Riverside, OR?
The median last spring frost in Riverside, OR is June 7. There is still about a 10% chance of frost after June 28, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Riverside, OR?
The median first fall frost is September 6, with about a 10% chance of frost before August 22.
How long is the growing season in Riverside, OR?
About 91 days between the median last spring frost and first fall frost.
What planting zone is Riverside, OR?
Riverside, OR is in USDA hardiness zone 6a.