The best time to plant grass seed in Oregon is from mid-August to mid-September. In certain parts of Oregon, you can also plant from mid-May to mid-June because the conditions are favorable for seeds to germinate.
Oregon’s climate can be too dry, hot, or cold to grow grass seed at other times of the year. Weeds can also compete with young grass sown in the summer. We’ll explain what conditions are favorable for planting grass in Oregon and what times of year those conditions exist.
The best times to plant grass seed
The optimal conditions for you to plant and grow grass seed in Oregon occur from mid-August to mid-September when the weather and soil are still warm but not hot, and definitely not cold.
The ideal air planting temperature is between 60 and 85 degrees Fahrenheit, and the ideal soil temperatures are between 50 and 72 degrees Fahrenheit. As you’ll see below, Kentucky bluegrass and tall fescue are on the warmer side of the spectrum, so it’s important to know your grass type.
Alternatively, you can plant grass from late spring to early summer. As stated by Oregon State University, “In many parts of Oregon, the period from early May to approximately mid-June is a pretty good time to plant. Earlier plantings germinate and develop slowly, so there rarely is any advantage to planting early.”
The best time to plant, by grass type
Here’s a chart with the best times to plant each grass type in Oregon, based on soil temperature:
| Grass type | Optimal soil temperature | Best time to plant |
| Kentucky bluegrass | 60 to 65 degrees Fahrenheit | Mid-September |
| Perennial ryegrass | 50 to 65 degrees Fahrenheit | Mid-September |
| Tall fescue | 59 to 72 degrees Fahrenheit | Early to mid-September |
| Fine fescue | 50 to 65 degrees Fahrenheit | Mid-September |
If you don’t know the best grass type to choose, here’s a list of the best Oregon grasses.
When not to seed in Oregon
So when should you NOT plant grass in Oregon?
- Late fall: Lawns planted in the late fall may struggle with wild grasses and weeds.
- Early spring: In the early spring, grass germinates and develops slowly because the ground is still cold. It’s better to wait a few weeks.
- Mid-summer: In the summer, temperatures are too high and your new grass may struggle if its roots aren’t well developed yet. It will also face competition from summer weeds.
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