Cedar Mill, OR planting zone & frost dates
Cedar Mill is in USDA hardiness zone 8b. The last spring frost usually comes around February 11 and the first fall frost around December 5, for a growing season of about 303 days.
Planting calendar for Cedar Mill
Dates are counted from the average last spring frost (February 11) 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: Dec 17 – Dec 31 Transplant outdoors: Feb 18 – Feb 25 |
| Peppers | Start seeds indoors: Dec 3 – Dec 17 Transplant outdoors: Feb 25 – Mar 4 |
| Eggplant | Start seeds indoors: Dec 3 – Dec 17 Transplant outdoors: Feb 25 – Mar 4 |
| Broccoli | Start seeds indoors: Dec 3 – Dec 17 Transplant outdoors: Jan 14 – Jan 28 |
| Cabbage | Start seeds indoors: Dec 3 – Dec 17 Transplant outdoors: Jan 14 – Jan 28 |
| Onions (sets) | Plant outdoors: Jan 14 – Jan 28 |
| Peas | Sow outdoors: Dec 31 – Jan 14 |
| Spinach | Sow outdoors: Dec 31 – Jan 14 |
| Lettuce | Sow outdoors: Jan 14 – Jan 28 |
| Carrots | Sow outdoors: Jan 14 – Jan 28 |
| Potatoes | Plant outdoors: Jan 14 – Jan 28 |
| Beans | Sow outdoors: Feb 18 – Feb 25 |
| Sweet corn | Sow outdoors: Feb 18 – Feb 25 |
| Cucumbers | Sow outdoors: Feb 18 – Feb 25 |
| Squash & zucchini | Sow outdoors: Feb 18 – Feb 25 |
| Basil | Start seeds indoors: Dec 31 – Jan 14 Transplant outdoors: Feb 18 – Feb 25 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Oct 10 (8 weeks before the average first fall frost on Dec 5).
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 | Dec 26 | Feb 11 | Mar 5 |
| First 32°F frost in fall is before | Jan 12 | Dec 5 | Nov 11 |
How to read it: in spring there is a 10% chance of a frost after March 5, so that is a safe date for tender plants. In fall there is a 10% chance of frost before November 11. A hard freeze (28°F) usually ends around January 6.
Nearby cities
Questions
What growing zone is Cedar Mill, OR?
Cedar Mill 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 Cedar Mill?
The average last spring frost (32°F) in Cedar Mill is February 11. There is still a 10% chance of frost until March 5.
When can I plant tomatoes in Cedar Mill?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Feb 18 – Feb 25. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Nature Park-Beaverton, OR (USC00355945), 3.7 km (2.3 mi) from the city center, elevation 56 m, based on 12 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.