Seattle, WA planting zone & frost dates
Seattle is in USDA hardiness zone 9a. The last spring frost usually comes around March 13 and the first fall frost around November 17, for a growing season of about 247 days.
Planting calendar for Seattle
Dates are counted from the average last spring frost (March 13) 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 16 – Jan 30 Transplant outdoors: Mar 20 – Mar 27 |
| Peppers | Start seeds indoors: Jan 2 – Jan 16 Transplant outdoors: Mar 27 – Apr 3 |
| Eggplant | Start seeds indoors: Jan 2 – Jan 16 Transplant outdoors: Mar 27 – Apr 3 |
| Broccoli | Start seeds indoors: Jan 2 – Jan 16 Transplant outdoors: Feb 13 – Feb 27 |
| Cabbage | Start seeds indoors: Jan 2 – Jan 16 Transplant outdoors: Feb 13 – Feb 27 |
| Onions (sets) | Plant outdoors: Feb 13 – Feb 27 |
| Peas | Sow outdoors: Jan 30 – Feb 13 |
| Spinach | Sow outdoors: Jan 30 – Feb 13 |
| Lettuce | Sow outdoors: Feb 13 – Feb 27 |
| Carrots | Sow outdoors: Feb 13 – Feb 27 |
| Potatoes | Plant outdoors: Feb 13 – Feb 27 |
| Beans | Sow outdoors: Mar 20 – Mar 27 |
| Sweet corn | Sow outdoors: Mar 20 – Mar 27 |
| Cucumbers | Sow outdoors: Mar 20 – Mar 27 |
| Squash & zucchini | Sow outdoors: Mar 20 – Mar 27 |
| Basil | Start seeds indoors: Jan 30 – Feb 13 Transplant outdoors: Mar 20 – Mar 27 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 22 (8 weeks before the average first fall frost on Nov 17).
Useful for zone 9a 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
- Shade cloth — for hot summers
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Feb 20 | Mar 13 | Apr 1 |
| First 32°F frost in fall is before | Dec 6 | Nov 17 | Nov 1 |
How to read it: in spring there is a 10% chance of a frost after April 1, so that is a safe date for tender plants. In fall there is a 10% chance of frost before November 1. A hard freeze (28°F) usually ends around February 18.
Hardiness zone by ZIP code in Seattle
- 98101 zone 9a
- 98102 zone 9a
- 98103 zone 9a
- 98104 zone 9a
- 98105 zone 9a
- 98106 zone 9a
- 98107 zone 9a
- 98108 zone 9a
- 98109 zone 9a
- 98111 zone 9a
- 98112 zone 9a
- 98113 zone 9a
- 98114 zone 9a
- 98115 zone 9a
- 98116 zone 9a
- 98117 zone 9a
- 98118 zone 9a
- 98119 zone 9a
- 98121 zone 9a
- 98122 zone 9a
- 98124 zone 9a
- 98125 zone 9a
- 98126 zone 9a
- 98127 zone 9a
- 98129 zone 9a
- 98131 zone 9a
- 98133 zone 9a
- 98134 zone 9a
- 98136 zone 9a
- 98138 zone 9a
- 98139 zone 9a
- 98141 zone 9a
- 98144 zone 9a
- 98145 zone 9a
- 98146 zone 9a
- 98148 zone 9a
- 98154 zone 9a
- 98155 zone 9a
- 98158 zone 9a
- 98160 zone 9a
- 98161 zone 9a
- 98164 zone 9a
- 98165 zone 9a
- 98166 zone 9a
- 98168 zone 9a
- 98170 zone 9a
- 98174 zone 9a
- 98175 zone 9a
- 98177 zone 9a
- 98178 zone 9a
- 98181 zone 9a
- 98185 zone 9a
- 98188 zone 9a
- 98190 zone 9a
- 98191 zone 9a
- 98194 zone 9a
- 98195 zone 9a
- 98198 zone 9a
- 98199 zone 9a
Nearby cities
- Columbia City zone 9a, last frost Mar 13
- White Center zone 9a, last frost Mar 13
- Mercer Island zone 9a, last frost Mar 13
- Bellevue zone 9a, last frost Mar 8
- Burien zone 9a, last frost Mar 2
- Bryn Mawr-Skyway zone 9a, last frost Mar 13
- Kirkland zone 8b, last frost Mar 8
- Shoreline zone 9a, last frost Mar 8
Questions
What growing zone is Seattle, WA?
Seattle is in USDA Plant Hardiness Zone 9a (average extreme winter low 20°F to 25°F), according to the USDA 2023 map.
When is the last frost in Seattle?
The average last spring frost (32°F) in Seattle is March 13. There is still a 10% chance of frost until April 1.
When can I plant tomatoes in Seattle?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Mar 20 – Mar 27. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Seattle Boeing Fld, WA (USW00024234), 8.8 km (5.5 mi) from the city center, elevation 6 m, based on 18 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.