The 2023 USDA Hardiness Zone Map places Oregon in growing zones 5a to 9b. Most of the state is in zones 6a to 9a, with the lowest average temperatures ranging between -10 and -5 degrees Fahrenheit.
Understanding your zone helps you know which plants and grasses will thrive in your landscape. This article will go deeper into each planting zone in Oregon and explain what that means for you.
Overview of Oregon growing zones
Oregon is primarily in zones 6a to 9a. The western regions have mild, wet winters and arid, hot summers. Most of the Oregon coast is in zone 9, where temperatures get as low as 20 to 25 degrees Fahrenheit. A segment of the southwestern coast is in 9b, where temperatures don’t drop much below 25 to 30 degrees.
The eastern area and mountain regions have less precipitation and are colder. In a smaller portion of the state, high-elevation areas, like the Blue Mountain, are in zone 5. Average temperatures fall as low as -20 to -10 degrees Fahrenheit.
Here is the USDA Plant Hardiness Zone Map for The Beaver State:
Willamette Valley
Most of Willamette Valley is in zones 8a and 8b, where the lowest average temperatures are between 10 and 20 degrees Fahrenheit. The climate is moderate and this region is cooler and experiences more rainfall. The average first frost date is Oct. 27. April 20 is the average last frost date. The Willamette Valley area is completely frost-free between May 23 and Sept. 30.
Read our article, Growing Zones of the Willamette Valley, for more information on the area’s zone.
Central Oregon
Central Oregon is primarily in zone 6. This region has dry and hot summers, with average lowest temperatures between -10 and 0 degrees Fahrenheit. The average first frost date depends on location within the central area, but it typically starts in mid to late August. For example, the first frost for Bend County typically occurs between Sept. 11 and Sept. 20. The first frost in Redmond is even earlier — Aug. 21 to Aug. 31.
Last frost dates vary widely, too. June 21 to June 30 are the last frost dates for both Bend and Redmond County, while Portland’s last frost date is March 11 through March 20.
The growing season is between 90 and 120 days. Higher elevations and the southern areas have a shorter growing season.
Lawn Love’s article, Growing Zones of Central Oregon, tells you more.
Southern Oregon
Most of southern Oregon ranges from zones 6a through 9a, meaning the lowest average temperature is between -10 and -5 degrees Fahrenheit in the cooler western areas and 20 to 25 degrees in some of the western areas of this region.
The westernmost area of southern Oregon is primarily in zones 8 to 9a, with average minimum temperatures between 10 to 20 degrees Fahrenheit.
The first frost depends on location but generally occurs between mid-September and late November. For example, Klamath Falls experiences its first frost between Sept. 11 and Sept. 15. Medford’s first frost typically happens around October 23, while Roseburg’s first frost generally occurs between Nov. 11 and Nov. 20.
Last frost dates also vary, usually occurring between April and June. Roseburg is one of the first cities in Southern Oregon to experience frost-free weather, with the last frost happening between April 1 and April 10. Medford follows, with the last frost ranging between mid-April and early May. Klamath Falls has frost dates as late as mid-June.
Check out our guide, Growing Zones of Southern Oregon, for more on how these zones affect you.
And our article, Oregon Native Plants for Landscaping, has great ideas for indigenous plants.
Planting zones of major Oregon cities:
Albany – Zone 8b, 15°F to 20°F
Beaverton – Zone 9a, 20°F to 25°F
Bend – Zone 6b, -5°F to 0°F
Corvallis – Zone 8b
Eugene – Zone 8b
Gresham – Zone 9a
Hillsboro – Zone 8b
Klamath Falls – Zone 6b
Medford – Zone 8b
Portland – Zone 9a
Redmond – Zone 6b
Roseburg – Zone 9a
Springfield – Zone 8b
Salem – Zone 8b
Tigard – Zone 9a
Call a professional
Oregon’s microclimates can make choosing the right plants challenging. If you want to ensure your yard showcases vegetation that will thrive, contact Lawn Love. Our experts will select varieties that turn your landscape into a beautiful work of art.
Main Image Credit: Visitor7 | Wikimedia Commons | CC BY-SA 3.0
