The best time to seed your lawn in Seattle is between April and May, but no later than Memorial Day. If you miss the deadline, fall is the second-best time – from around Labor Day to mid-October.
Always plant new grass when it actively grows because you’ll have the best chance of achieving a green, lush lawn.
Best time: between April 1 and Memorial Day
This is the best time to seed in Seattle for the following reasons:
- Cooler temperatures: Grasses in Seattle grow when the air temperature is between 50 and 75°F; it gives them time to germinate and establish before the summer heat arrives.
- Moisture: Seattle sees frequent, light rainfall in April and May, which facilitates grass growth.
- Optimal soil temperatures: Grasses grow best in soil temperatures between 50 and 65°F.
Second-best time: Labor Day to October 15
If you miss the spring deadline, the period between Labor Day and October 15 is a good time to plant grass seed, as conditions are similar.
Summer seeding
Though not recommended due to the intense heat, midsummer seeding is viable if there’s enough water available to support new growth. In this case, Washington State University recommends applying water in small amounts several times a day to maintain a moist surface.
When to overseed your Seattle lawn
September to October is the best time to overseed your Seattle lawn. The cooler nights, warm days, and precipitation support it. Additionally, the soil stays moist for longer, giving grass seeds enough humidity to germinate.
Overseed your lawn a month before the first frost so the seeds will have enough time to germinate.
Pro Tip: September to October is also a great time to fertilize your lawn. Read our article, When to Fertilize Your Lawn in Washington State, to learn more.
More lawn care and landscaping resources for Seattle
Read the following articles to take your Seattle yard to the next level:
Trust the pros
There’s no question that planting grass seed is hard. We also know you’d rather watch a Seahawks game than start a new lawn. But we’re here to help. Lawn Love’s pros will pick the best grass for your lawn and plant it.
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