Mount Vernon, WA planting zone & frost dates
Mount Vernon is in USDA hardiness zone 8b. The last spring frost usually comes around March 24 and the first fall frost around November 3, for a growing season of about 224 days.
Planting calendar for Mount Vernon
Dates are counted from the average last spring frost (March 24) 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 27 – Feb 10 Transplant outdoors: Mar 31 – Apr 7 |
| Peppers | Start seeds indoors: Jan 13 – Jan 27 Transplant outdoors: Apr 7 – Apr 14 |
| Eggplant | Start seeds indoors: Jan 13 – Jan 27 Transplant outdoors: Apr 7 – Apr 14 |
| Broccoli | Start seeds indoors: Jan 13 – Jan 27 Transplant outdoors: Feb 24 – Mar 10 |
| Cabbage | Start seeds indoors: Jan 13 – Jan 27 Transplant outdoors: Feb 24 – Mar 10 |
| Onions (sets) | Plant outdoors: Feb 24 – Mar 10 |
| Peas | Sow outdoors: Feb 10 – Feb 24 |
| Spinach | Sow outdoors: Feb 10 – Feb 24 |
| Lettuce | Sow outdoors: Feb 24 – Mar 10 |
| Carrots | Sow outdoors: Feb 24 – Mar 10 |
| Potatoes | Plant outdoors: Feb 24 – Mar 10 |
| Beans | Sow outdoors: Mar 31 – Apr 7 |
| Sweet corn | Sow outdoors: Mar 31 – Apr 7 |
| Cucumbers | Sow outdoors: Mar 31 – Apr 7 |
| Squash & zucchini | Sow outdoors: Mar 31 – Apr 7 |
| Basil | Start seeds indoors: Feb 10 – Feb 24 Transplant outdoors: Mar 31 – Apr 7 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 8 (8 weeks before the average first fall frost on Nov 3).
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 3 | Mar 24 | Apr 14 |
| First 32°F frost in fall is before | Nov 25 | Nov 3 | Oct 12 |
How to read it: in spring there is a 10% chance of a frost after April 14, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 12. A hard freeze (28°F) usually ends around February 27.
Hardiness zone by ZIP code in Mount Vernon
- 98273 zone 8b
- 98274 zone 8b
Nearby cities
- Sedro-Woolley zone 8b, last frost Mar 27
- Anacortes zone 8b, last frost Mar 8
- Arlington zone 8a, last frost Apr 22
- Camano zone 8b, last frost Mar 17
- Oak Harbor zone 8b, last frost Mar 13
- Bellingham zone 8b, last frost Apr 1
- Marysville zone 8b, last frost Mar 24
- Everett zone 8b, last frost Mar 24
Questions
What growing zone is Mount Vernon, WA?
Mount Vernon 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 Mount Vernon?
The average last spring frost (32°F) in Mount Vernon is March 24. There is still a 10% chance of frost until April 14.
When can I plant tomatoes in Mount Vernon?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Mar 31 – Apr 7. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Mt Vernon 3 Wnw, WA (USC00455678), 4.4 km (2.7 mi) from the city center, elevation 4 m, based on 14 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.