When To Plant Squash In Seattle

The best time to plant squash in Seattle is from late May through mid-June, once the soil has warmed to at least 60°F and all danger of frost has passed.
 
If you’ve been wondering when to plant squash in Seattle, timing really is everything here because our cool, wet springs can stall growth fast.
 
Plant too early and your squash seeds may rot in cold, soggy soil before they ever sprout.
 
Plant too late and you risk running out of warm days before your harvest fully matures.
 
In this post, we’ll walk through exactly when to plant squash in Seattle, how to prep your soil, and which varieties thrive best in our unique Pacific Northwest climate.
 
Let’s dig in.
 

When to Plant Squash in Seattle

Knowing when to plant squash in Seattle comes down to soil temperature, not just the calendar.
 
Here’s how to nail the timing so your plants get off to a strong start.
 

1. Wait Until Soil Reaches 60°F

Squash seeds need warm soil to germinate, ideally between 60°F and 70°F.
 
In Seattle, that usually happens in late May or early June, depending on how cool our spring has been.
 
You can grab an inexpensive soil thermometer and check a few inches down before planting.
 
If the soil is still hovering in the low 50s, hold off a little longer.
 

2. Watch for the Last Frost Date

Seattle’s average last frost date falls around March 15 to April 15 in most neighborhoods, but cold snaps can sneak in well past that.
 
That’s why many local gardeners wait until Memorial Day weekend to plant squash in Seattle.
 
Frost will kill young squash seedlings overnight, so patience here pays off big.
 

3. Start Seeds Indoors for a Head Start

If you want to plant squash in Seattle earlier, start seeds indoors about three to four weeks before your target transplant date.
 
Use biodegradable pots since squash roots hate being disturbed.
 
Harden them off gradually before moving them outside in late May or early June.
 
This gives you a jump on our short growing season without risking frost damage.
 

How to Prepare Your Seattle Soil for Squash

Once you know when to plant squash in Seattle, the next step is getting your soil ready.
 
Squash are heavy feeders, and our native soil here tends to be compacted and acidic.
 

1. Amend With Compost

Work several inches of rich compost into your beds before planting.
 
This improves drainage, which matters a lot in Seattle’s rainy climate.
 
Squash hate soggy roots, and good compost keeps the soil loose and healthy.
 

2. Build Raised Beds or Mounds

Raised beds warm up faster in spring and drain better during our wet spells.
 
Planting squash on small mounds also helps, since it keeps water from pooling around the stems.
 
This is one of the simplest tricks when you plant squash in Seattle.
 

3. Test and Adjust Your Soil pH

Squash prefer a pH between 6.0 and 6.8.
 
A quick soil test tells you whether you need to add lime to raise pH or sulfur to lower it.
 
Getting this right before you plant squash in Seattle sets your crop up for success.
 

Best Squash Varieties to Plant in Seattle

Choosing the right varieties makes a huge difference in our short, cool season.
 
Here are some reliable picks when you plant squash in Seattle.
 

1. Summer Squash: Zucchini and Yellow Crookneck

These grow fast and produce within 50 to 60 days, which fits our season nicely.
 
Varieties like ‘Black Beauty’ zucchini and ‘Early Prolific Straightneck’ perform well here.
 
Harvest them young and keep picking to encourage more fruit.
 

2. Winter Squash: Butternut and Delicata

Butternut and Delicata are two of the most reliable winter squash for Seattle gardens.
 
Delicata matures in about 100 days, while butternut needs closer to 110.
 
Both store well and taste fantastic roasted.
 

3. Look for Short-Season Varieties

Since our summers are mild, choose squash labeled “short-season” or “early.”
 
These varieties ripen faster and are bred for cooler climates.
 
That way, when you plant squash in Seattle, you’re working with the weather instead of against it.
 

So, When to Plant Squash in Seattle?

The best time to plant squash in Seattle is late May through mid-June, once soil hits 60°F and frost is behind us.
 
If you start seeds indoors in early May, amend your soil with compost, and pick short-season varieties, you’ll set yourself up for a healthy harvest.
 
Timing, warm soil, and the right varieties are the keys to success when you plant squash in Seattle.
 
Now get out there and get planting.