Mill Creek, WA planting zone & frost dates
Mill Creek is in USDA hardiness zone 8b. The last spring frost usually comes around March 9 and the first fall frost around November 17, for a growing season of about 250 days.
Planting calendar for Mill Creek
Dates are counted from the average last spring frost (March 9) 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 12 – Jan 26 Transplant outdoors: Mar 16 – Mar 23 |
| Peppers | Start seeds indoors: Dec 29 – Jan 12 Transplant outdoors: Mar 23 – Mar 30 |
| Eggplant | Start seeds indoors: Dec 29 – Jan 12 Transplant outdoors: Mar 23 – Mar 30 |
| Broccoli | Start seeds indoors: Dec 29 – Jan 12 Transplant outdoors: Feb 9 – Feb 23 |
| Cabbage | Start seeds indoors: Dec 29 – Jan 12 Transplant outdoors: Feb 9 – Feb 23 |
| Onions (sets) | Plant outdoors: Feb 9 – Feb 23 |
| Peas | Sow outdoors: Jan 26 – Feb 9 |
| Spinach | Sow outdoors: Jan 26 – Feb 9 |
| Lettuce | Sow outdoors: Feb 9 – Feb 23 |
| Carrots | Sow outdoors: Feb 9 – Feb 23 |
| Potatoes | Plant outdoors: Feb 9 – Feb 23 |
| Beans | Sow outdoors: Mar 16 – Mar 23 |
| Sweet corn | Sow outdoors: Mar 16 – Mar 23 |
| Cucumbers | Sow outdoors: Mar 16 – Mar 23 |
| Squash & zucchini | Sow outdoors: Mar 16 – Mar 23 |
| Basil | Start seeds indoors: Jan 26 – Feb 9 Transplant outdoors: Mar 16 – Mar 23 |
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 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 15 | Mar 9 | Mar 29 |
| First 32°F frost in fall is before | Dec 7 | Nov 17 | Oct 31 |
How to read it: in spring there is a 10% chance of a frost after March 29, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 31. A hard freeze (28°F) usually ends around February 13.
Hardiness zone by ZIP code in Mill Creek
- 98082 zone 8b
Nearby cities
- Mill Creek East zone 8b, last frost Mar 9
- Martha Lake zone 9a, last frost Mar 9
- Eastmont zone 8b, last frost Mar 9
- North Creek zone 8b, last frost Mar 9
- Silver Firs zone 8b, last frost Mar 9
- Bothell West zone 8b, last frost Mar 9
- Picnic Point-North Lynnwood zone 8b, last frost Mar 9
- Bothell zone 8b, last frost Mar 8
Questions
What growing zone is Mill Creek, WA?
Mill Creek 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 Mill Creek?
The average last spring frost (32°F) in Mill Creek is March 9. There is still a 10% chance of frost until March 29.
When can I plant tomatoes in Mill Creek?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Mar 16 – Mar 23. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Everett Snohomish Ap, WA (USW00024222), 7.8 km (4.8 mi) from the city center, elevation 185 m, based on 22 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.