Milwaukie, OR planting zone & frost dates
Milwaukie is in USDA hardiness zone 9a. The last spring frost usually comes around February 25 and the first fall frost around December 1, for a growing season of about 280 days.
Planting calendar for Milwaukie
Dates are counted from the average last spring frost (February 25) 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 31 – Jan 14 Transplant outdoors: Mar 4 – Mar 11 |
| Peppers | Start seeds indoors: Dec 17 – Dec 31 Transplant outdoors: Mar 11 – Mar 18 |
| Eggplant | Start seeds indoors: Dec 17 – Dec 31 Transplant outdoors: Mar 11 – Mar 18 |
| Broccoli | Start seeds indoors: Dec 17 – Dec 31 Transplant outdoors: Jan 28 – Feb 11 |
| Cabbage | Start seeds indoors: Dec 17 – Dec 31 Transplant outdoors: Jan 28 – Feb 11 |
| Onions (sets) | Plant outdoors: Jan 28 – Feb 11 |
| Peas | Sow outdoors: Jan 14 – Jan 28 |
| Spinach | Sow outdoors: Jan 14 – Jan 28 |
| Lettuce | Sow outdoors: Jan 28 – Feb 11 |
| Carrots | Sow outdoors: Jan 28 – Feb 11 |
| Potatoes | Plant outdoors: Jan 28 – Feb 11 |
| Beans | Sow outdoors: Mar 4 – Mar 11 |
| Sweet corn | Sow outdoors: Mar 4 – Mar 11 |
| Cucumbers | Sow outdoors: Mar 4 – Mar 11 |
| Squash & zucchini | Sow outdoors: Mar 4 – Mar 11 |
| Basil | Start seeds indoors: Jan 14 – Jan 28 Transplant outdoors: Mar 4 – Mar 11 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Oct 6 (8 weeks before the average first fall frost on Dec 1).
Useful for zone 9a 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
- Shade cloth — for hot summers
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Jan 24 | Feb 25 | Mar 21 |
| First 32°F frost in fall is before | Dec 27 | Dec 1 | Nov 10 |
How to read it: in spring there is a 10% chance of a frost after March 21, so that is a safe date for tender plants. In fall there is a 10% chance of frost before November 10. A hard freeze (28°F) usually ends around January 31.
Nearby cities
- Oak Grove zone 9a, last frost Mar 18
- Lake Oswego zone 9a, last frost Mar 18
- Oatfield zone 9a, last frost Mar 18
- Gladstone zone 9a, last frost Mar 18
- West Linn zone 9a, last frost Mar 18
- Portland zone 9a, last frost Feb 25
- Oregon City zone 9a, last frost Mar 18
- Happy Valley zone 8b, last frost Mar 18
Questions
What growing zone is Milwaukie, OR?
Milwaukie is in USDA Plant Hardiness Zone 9a (average extreme winter low 20°F to 25°F), according to the USDA 2023 map.
When is the last frost in Milwaukie?
The average last spring frost (32°F) in Milwaukie is February 25. There is still a 10% chance of frost until March 21.
When can I plant tomatoes in Milwaukie?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Mar 4 – Mar 11. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Portland Kgw-Tv, OR (USC00356749), 8.9 km (5.5 mi) from the city center, elevation 48 m, based on 24 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.