Washington, UT planting zone & frost dates
Washington is in USDA hardiness zone 8b. The last spring frost usually comes around March 14 and the first fall frost around November 10, for a growing season of about 239 days.
Planting calendar for Washington
Dates are counted from the average last spring frost (March 14) 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 17 – Jan 31 Transplant outdoors: Mar 21 – Mar 28 |
| Peppers | Start seeds indoors: Jan 3 – Jan 17 Transplant outdoors: Mar 28 – Apr 4 |
| Eggplant | Start seeds indoors: Jan 3 – Jan 17 Transplant outdoors: Mar 28 – Apr 4 |
| Broccoli | Start seeds indoors: Jan 3 – Jan 17 Transplant outdoors: Feb 14 – Feb 28 |
| Cabbage | Start seeds indoors: Jan 3 – Jan 17 Transplant outdoors: Feb 14 – Feb 28 |
| Onions (sets) | Plant outdoors: Feb 14 – Feb 28 |
| Peas | Sow outdoors: Jan 31 – Feb 14 |
| Spinach | Sow outdoors: Jan 31 – Feb 14 |
| Lettuce | Sow outdoors: Feb 14 – Feb 28 |
| Carrots | Sow outdoors: Feb 14 – Feb 28 |
| Potatoes | Plant outdoors: Feb 14 – Feb 28 |
| Beans | Sow outdoors: Mar 21 – Mar 28 |
| Sweet corn | Sow outdoors: Mar 21 – Mar 28 |
| Cucumbers | Sow outdoors: Mar 21 – Mar 28 |
| Squash & zucchini | Sow outdoors: Mar 21 – Mar 28 |
| Basil | Start seeds indoors: Jan 31 – Feb 14 Transplant outdoors: Mar 21 – Mar 28 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 15 (8 weeks before the average first fall frost on Nov 10).
Useful for zone 8b 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 | Feb 27 | Mar 14 | Apr 6 |
| First 32°F frost in fall is before | Nov 22 | Nov 10 | Oct 27 |
How to read it: in spring there is a 10% chance of a frost after April 6, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 27. A hard freeze (28°F) usually ends around February 27.
Hardiness zone by ZIP code in Washington
- 84780 zone 8b
Nearby cities
- Saint George zone 8b, last frost Mar 14
- Hurricane zone 8a, last frost Apr 1
- Cedar City zone 6b, last frost May 4
- Santaquin zone 6b, last frost May 4
- Payson zone 7a, last frost May 4
- Spanish Fork zone 7a, last frost Apr 25
- Eagle Mountain zone 6b, last frost Jun 2
- Springville zone 7a, last frost Apr 25
Questions
What growing zone is Washington, UT?
Washington is in USDA Plant Hardiness Zone 8b (average extreme winter low 15°F to 20°F), according to the USDA 2023 map.
When is the last frost in Washington?
The average last spring frost (32°F) in Washington is March 14. There is still a 10% chance of frost until April 6.
When can I plant tomatoes in Washington?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Mar 21 – Mar 28. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station St George, UT (USC00427516), 8.8 km (5.5 mi) from the city center, elevation 871 m, based on 23 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.