Ellensburg, WA planting zone & frost dates
Ellensburg is in USDA hardiness zone 6b. The last spring frost usually comes around May 8 and the first fall frost around October 2, for a growing season of about 146 days.
Planting calendar for Ellensburg
Dates are counted from the average last spring frost (May 8) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Mar 13 – Mar 27 Transplant outdoors: May 15 – May 22 |
| Peppers | Start seeds indoors: Feb 27 – Mar 13 Transplant outdoors: May 22 – May 29 |
| Eggplant | Start seeds indoors: Feb 27 – Mar 13 Transplant outdoors: May 22 – May 29 |
| Broccoli | Start seeds indoors: Feb 27 – Mar 13 Transplant outdoors: Apr 10 – Apr 24 |
| Cabbage | Start seeds indoors: Feb 27 – Mar 13 Transplant outdoors: Apr 10 – Apr 24 |
| Onions (sets) | Plant outdoors: Apr 10 – Apr 24 |
| Peas | Sow outdoors: Mar 27 – Apr 10 |
| Spinach | Sow outdoors: Mar 27 – Apr 10 |
| Lettuce | Sow outdoors: Apr 10 – Apr 24 |
| Carrots | Sow outdoors: Apr 10 – Apr 24 |
| Potatoes | Plant outdoors: Apr 10 – Apr 24 |
| Beans | Sow outdoors: May 15 – May 22 |
| Sweet corn | Sow outdoors: May 15 – May 22 |
| Cucumbers | Sow outdoors: May 15 – May 22 |
| Squash & zucchini | Sow outdoors: May 15 – May 22 |
| Basil | Start seeds indoors: Mar 27 – Apr 10 Transplant outdoors: May 15 – May 22 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 7 (8 weeks before the average first fall frost on Oct 2).
Useful for zone 6b gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Cold frame / mini greenhouse — adds weeks to a short season
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Apr 25 | May 8 | May 25 |
| First 32°F frost in fall is before | Oct 14 | Oct 2 | Sep 20 |
How to read it: in spring there is a 10% chance of a frost after May 25, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 20. A hard freeze (28°F) usually ends around April 23.
Hardiness zone by ZIP code in Ellensburg
- 98926 zone 7a
Nearby cities
- Yakima zone 7a, last frost May 8
- West Valley zone 7a, last frost Apr 8
- Wenatchee zone 7b, last frost Apr 4
- East Wenatchee zone 7b, last frost Apr 4
- Sunnyside zone 7b, last frost May 1
- Grandview zone 7b, last frost May 1
- Moses Lake zone 7a, last frost Apr 27
- West Richland zone 7b, last frost Apr 6
Questions
What growing zone is Ellensburg, WA?
Ellensburg is in USDA Plant Hardiness Zone 6b (average extreme winter low -5°F to 0°F), according to the USDA 2023 map. Some ZIP codes of the city fall in zone 7a.
When is the last frost in Ellensburg?
The average last spring frost (32°F) in Ellensburg is May 8. There is still a 10% chance of frost until May 25.
When can I plant tomatoes in Ellensburg?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 15 – May 22. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Ellensburg, WA (USC00452505), 3.1 km (1.9 mi) from the city center, elevation 451 m, based on 26 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.