Sedro-Woolley, WA planting zone & frost dates
Sedro-Woolley is in USDA hardiness zone 8b. The last spring frost usually comes around March 27 and the first fall frost around November 6, for a growing season of about 224 days.
Planting calendar for Sedro-Woolley
Dates are counted from the average last spring frost (March 27) 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 30 – Feb 13 Transplant outdoors: Apr 3 – Apr 10 |
| Peppers | Start seeds indoors: Jan 16 – Jan 30 Transplant outdoors: Apr 10 – Apr 17 |
| Eggplant | Start seeds indoors: Jan 16 – Jan 30 Transplant outdoors: Apr 10 – Apr 17 |
| Broccoli | Start seeds indoors: Jan 16 – Jan 30 Transplant outdoors: Feb 27 – Mar 13 |
| Cabbage | Start seeds indoors: Jan 16 – Jan 30 Transplant outdoors: Feb 27 – Mar 13 |
| Onions (sets) | Plant outdoors: Feb 27 – Mar 13 |
| Peas | Sow outdoors: Feb 13 – Feb 27 |
| Spinach | Sow outdoors: Feb 13 – Feb 27 |
| Lettuce | Sow outdoors: Feb 27 – Mar 13 |
| Carrots | Sow outdoors: Feb 27 – Mar 13 |
| Potatoes | Plant outdoors: Feb 27 – Mar 13 |
| Beans | Sow outdoors: Apr 3 – Apr 10 |
| Sweet corn | Sow outdoors: Apr 3 – Apr 10 |
| Cucumbers | Sow outdoors: Apr 3 – Apr 10 |
| Squash & zucchini | Sow outdoors: Apr 3 – Apr 10 |
| Basil | Start seeds indoors: Feb 13 – Feb 27 Transplant outdoors: Apr 3 – Apr 10 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 11 (8 weeks before the average first fall frost on Nov 6).
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 | Mar 8 | Mar 27 | Apr 17 |
| First 32°F frost in fall is before | Nov 28 | Nov 6 | Oct 15 |
How to read it: in spring there is a 10% chance of a frost after April 17, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 15. A hard freeze (28°F) usually ends around March 1.
Nearby cities
- Mount Vernon zone 8b, last frost Mar 24
- Arlington zone 8a, last frost Apr 22
- Bellingham zone 8b, last frost Apr 1
- Anacortes zone 8b, last frost Mar 8
- Camano zone 8b, last frost Mar 17
- Marysville zone 8b, last frost Mar 24
- Oak Harbor zone 8b, last frost Mar 13
- Lynden zone 8a, last frost Apr 18
Questions
What growing zone is Sedro-Woolley, WA?
Sedro-Woolley 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 Sedro-Woolley?
The average last spring frost (32°F) in Sedro-Woolley is March 27. There is still a 10% chance of frost until April 17.
When can I plant tomatoes in Sedro-Woolley?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 3 – Apr 10. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Sedro-Woolley, WA (USC00457507), 0.9 km (0.6 mi) from the city center, elevation 18 m, based on 20 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.