Oak Harbor, WA planting zone & frost dates
Oak Harbor is in USDA hardiness zone 8b. The last spring frost usually comes around March 13 and the first fall frost around November 14, for a growing season of about 244 days.
Planting calendar for Oak Harbor
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 19 (8 weeks before the average first fall frost on Nov 14).
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 20 | Mar 13 | Apr 1 |
| First 32°F frost in fall is before | Dec 5 | Nov 14 | Oct 26 |
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 October 26. A hard freeze (28°F) usually ends around February 18.
Hardiness zone by ZIP code in Oak Harbor
- 98277 zone 8b
- 98278 zone 8b
Nearby cities
- Camano zone 8b, last frost Mar 17
- Anacortes zone 8b, last frost Mar 8
- Mount Vernon zone 8b, last frost Mar 24
- Sedro-Woolley zone 8b, last frost Mar 27
- Mukilteo zone 8b, last frost Mar 9
- Bellingham zone 8b, last frost Apr 1
- Marysville zone 8b, last frost Mar 24
- Arlington zone 8a, last frost Apr 22
Questions
What growing zone is Oak Harbor, WA?
Oak Harbor 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 Oak Harbor?
The average last spring frost (32°F) in Oak Harbor is March 13. There is still a 10% chance of frost until April 1.
When can I plant tomatoes in Oak Harbor?
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 Whidbey Island Nas, WA (USW00024255), 6.6 km (4.1 mi) from the city center, elevation 14 m, based on 21 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.