Kennewick, WA planting zone & frost dates
Kennewick is in USDA hardiness zone 7b. The last spring frost usually comes around March 28 and the first fall frost around October 30, for a growing season of about 216 days.
Planting calendar for Kennewick
Dates are counted from the average last spring frost (March 28) 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: Jan 31 – Feb 14 Transplant outdoors: Apr 4 – Apr 11 |
| Peppers | Start seeds indoors: Jan 17 – Jan 31 Transplant outdoors: Apr 11 – Apr 18 |
| Eggplant | Start seeds indoors: Jan 17 – Jan 31 Transplant outdoors: Apr 11 – Apr 18 |
| Broccoli | Start seeds indoors: Jan 17 – Jan 31 Transplant outdoors: Feb 28 – Mar 14 |
| Cabbage | Start seeds indoors: Jan 17 – Jan 31 Transplant outdoors: Feb 28 – Mar 14 |
| Onions (sets) | Plant outdoors: Feb 28 – Mar 14 |
| Peas | Sow outdoors: Feb 14 – Feb 28 |
| Spinach | Sow outdoors: Feb 14 – Feb 28 |
| Lettuce | Sow outdoors: Feb 28 – Mar 14 |
| Carrots | Sow outdoors: Feb 28 – Mar 14 |
| Potatoes | Plant outdoors: Feb 28 – Mar 14 |
| Beans | Sow outdoors: Apr 4 – Apr 11 |
| Sweet corn | Sow outdoors: Apr 4 – Apr 11 |
| Cucumbers | Sow outdoors: Apr 4 – Apr 11 |
| Squash & zucchini | Sow outdoors: Apr 4 – Apr 11 |
| Basil | Start seeds indoors: Feb 14 – Feb 28 Transplant outdoors: Apr 4 – Apr 11 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 4 (8 weeks before the average first fall frost on Oct 30).
Useful for zone 7b 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
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Mar 9 | Mar 28 | Apr 10 |
| First 32°F frost in fall is before | Nov 15 | Oct 30 | Oct 18 |
How to read it: in spring there is a 10% chance of a frost after April 10, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 18. A hard freeze (28°F) usually ends around March 8.
Hardiness zone by ZIP code in Kennewick
- 99336 zone 7b
- 99337 zone 7b
- 99338 zone 7b
Nearby cities
- Pasco zone 7b, last frost Mar 28
- Richland zone 7b, last frost Apr 6
- West Richland zone 7b, last frost Apr 6
- Grandview zone 7b, last frost May 1
- Walla Walla zone 7a, last frost Mar 27
- Sunnyside zone 7b, last frost May 1
- Moses Lake zone 7a, last frost Apr 27
- Yakima zone 7a, last frost May 8
Questions
What growing zone is Kennewick, WA?
Kennewick is in USDA Plant Hardiness Zone 7b (average extreme winter low 5°F to 10°F), according to the USDA 2023 map.
When is the last frost in Kennewick?
The average last spring frost (32°F) in Kennewick is March 28. There is still a 10% chance of frost until April 10.
When can I plant tomatoes in Kennewick?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 4 – Apr 11. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Kennewick, WA (USC00454154), 2.8 km (1.7 mi) from the city center, elevation 119 m, based on 27 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.