When To Plant Squash In Washington State

The best time to plant squash in Washington state is from late May to mid-June, once the soil has warmed and the danger of frost has passed.
 
Squash loves heat, and Washington’s cool spring nights can stunt it if you plant too early.
 
If you’re wondering when to plant squash in Washington state, the short answer is: wait until nighttime temperatures stay reliably above 50°F.
 
In this post, we’ll break down the best planting windows for both summer and winter squash, how your region affects timing, and tips for getting a head start.
 
Let’s dig in.
 

When to Plant Squash in Washington State

Knowing when to plant squash in Washington state comes down to two things: soil temperature and frost dates.
 
Squash seeds germinate best when soil is at least 60°F, and seedlings sulk in cold, wet ground.
 
Here’s how the timing shakes out across the state.
 

1. Wait for the Last Frost

Washington’s last frost date varies widely depending on where you garden.
 
In western Washington (Seattle, Tacoma, Bellingham), the last frost typically falls between late April and mid-May.
 
In eastern Washington (Spokane, Yakima, Tri-Cities), it can stretch into mid-to-late May.
 
So when you plant squash in Washington state, aim for two weeks after your local last frost date.
 
That usually lands you in late May or early June.
 

2. Watch Soil Temperature, Not Just the Calendar

The calendar is a guide, but soil temperature is the real boss.
 
If you plant squash in Washington state before the ground hits 60°F, seeds may rot instead of sprout.
 
Grab a soil thermometer and check a few inches down around mid-morning.
 
If it’s still in the 50s, give it another week.
 

3. Start Seeds Indoors for a Head Start

Since Washington’s growing season is shorter than ideal for squash, starting seeds indoors helps a lot.
 
Sow squash seeds indoors about three to four weeks before your last frost date.
 
That means early to mid-May for most of Washington.
 
Harden them off for a week before transplanting so they adjust to outdoor conditions.
 
When you transplant squash in Washington state, do it once nights stay above 50°F.
 

Regional Timing for Planting Squash in Washington State

Washington isn’t one climate, so your zip code matters.
 
Here’s how when to plant squash in Washington state changes by region.
 

1. Western Washington

West of the Cascades, springs are cool and damp.
 
Plant squash in Washington state here from late May through mid-June.
 
Raised beds help because they warm up faster than in-ground soil.
 

2. Eastern Washington

Eastern Washington has hotter summers but colder spring nights.
 
When you plant squash in Washington state on this side, target late May to early June.
 
The extra heat helps squash catch up fast once it’s in the ground.
 

3. Higher Elevations and Mountain Areas

If you garden above 2,000 feet, your window shrinks.
 
Plant squash in Washington state there in early to mid-June, and choose short-season varieties.
 
‘Cause cool nights at elevation can slow growth dramatically.
 

Summer vs. Winter Squash Planting Times

Not all squash follow the same schedule.
 
Here’s how planting squash in Washington state differs between types.
 

1. Summer Squash (Zucchini, Yellow Crookneck)

Summer squash grows fast and produces quickly.
 
When you plant squash in Washington state, put summer varieties in from late May to mid-June.
 
You can even succession-plant every three weeks until early July for a steady harvest.
 

2. Winter Squash (Butternut, Acorn, Delicata)

Winter squash needs a longer season to mature.
 
Plant squash in Washington state for winter types by early June at the latest.
 
Delicata and acorn are safer bets in short-season areas.
 
Butternut needs the full summer, so start it indoors if you’re west of the Cascades.
 

So, When Should You Plant Squash in Washington State?

The best time to plant squash in Washington state is late May to mid-June, after the last frost and once soil hits 60°F.
 
Western Washington gardeners should lean toward late May with raised beds, while eastern Washington can plant around the same time thanks to warmer days.
 
Starting seeds indoors three to four weeks early gives you a jump on the short season.
 
So if you’ve been asking when to plant squash in Washington state, the answer is simple: wait for warm soil, watch your local frost date, and get those seeds in by early June for the best harvest.
 
Happy planting.