Gladstone, OR planting zone & frost dates
Gladstone is in USDA hardiness zone 9a. The last spring frost usually comes around March 18 and the first fall frost around November 18, for a growing season of about 244 days.
Planting calendar for Gladstone
Dates are counted from the average last spring frost (March 18) 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 21 – Feb 4 Transplant outdoors: Mar 25 – Apr 1 |
| Peppers | Start seeds indoors: Jan 7 – Jan 21 Transplant outdoors: Apr 1 – Apr 8 |
| Eggplant | Start seeds indoors: Jan 7 – Jan 21 Transplant outdoors: Apr 1 – Apr 8 |
| Broccoli | Start seeds indoors: Jan 7 – Jan 21 Transplant outdoors: Feb 18 – Mar 4 |
| Cabbage | Start seeds indoors: Jan 7 – Jan 21 Transplant outdoors: Feb 18 – Mar 4 |
| Onions (sets) | Plant outdoors: Feb 18 – Mar 4 |
| Peas | Sow outdoors: Feb 4 – Feb 18 |
| Spinach | Sow outdoors: Feb 4 – Feb 18 |
| Lettuce | Sow outdoors: Feb 18 – Mar 4 |
| Carrots | Sow outdoors: Feb 18 – Mar 4 |
| Potatoes | Plant outdoors: Feb 18 – Mar 4 |
| Beans | Sow outdoors: Mar 25 – Apr 1 |
| Sweet corn | Sow outdoors: Mar 25 – Apr 1 |
| Cucumbers | Sow outdoors: Mar 25 – Apr 1 |
| Squash & zucchini | Sow outdoors: Mar 25 – Apr 1 |
| Basil | Start seeds indoors: Feb 4 – Feb 18 Transplant outdoors: Mar 25 – Apr 1 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 23 (8 weeks before the average first fall frost on Nov 18).
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 | Feb 19 | Mar 18 | Apr 11 |
| First 32°F frost in fall is before | Dec 12 | Nov 18 | Oct 30 |
How to read it: in spring there is a 10% chance of a frost after April 11, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 30. A hard freeze (28°F) usually ends around February 12.
Hardiness zone by ZIP code in Gladstone
- 97027 zone 9a
Nearby cities
- West Linn zone 9a, last frost Mar 18
- Oregon City zone 9a, last frost Mar 18
- Oatfield zone 9a, last frost Mar 18
- Oak Grove zone 9a, last frost Mar 18
- Milwaukie zone 9a, last frost Feb 25
- Lake Oswego zone 9a, last frost Mar 18
- Happy Valley zone 8b, last frost Mar 18
- Damascus zone 8b, last frost Mar 18
Questions
What growing zone is Gladstone, OR?
Gladstone 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 Gladstone?
The average last spring frost (32°F) in Gladstone is March 18. There is still a 10% chance of frost until April 11.
When can I plant tomatoes in Gladstone?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Mar 25 – Apr 1. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Oregon City, OR (USC00356334), 2.9 km (1.8 mi) from the city center, elevation 51 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.