When To Plant Broccoli In Seattle

The best time to plant broccoli in Seattle is from mid-July through August for a fall harvest, or in late February to early April for a spring crop.
 
Broccoli loves Seattle’s cool, moist climate, and if you time your planting right, you’ll be harvesting tasty heads before you know it.
 
If you’ve been wondering when to plant broccoli in Seattle, the short answer is that this city’s mild maritime weather gives you two solid windows each year.
 
In this post, we’ll walk through exactly when to plant broccoli in Seattle, why the timing matters so much, and how to make the most of both growing seasons.
 
Let’s dig in.

When to Plant Broccoli in Seattle

When you plant broccoli in Seattle, timing is everything, and here’s why:

1. Fall Planting Is the Star

The best time to plant broccoli in Seattle is mid-July through August, because the plants mature in the cool, rainy days of autumn.
 
Broccoli hates heat, and Seattle’s summers rarely get brutal, but late summer planting means your broccoli heads up just as temperatures drop.
 
Sow seeds indoors around early July or direct sow outdoors by mid-July, and you’ll be harvesting from October into November.
 
This fall window is why so many Seattle gardeners say fall broccoli beats spring broccoli every single time.

2. Spring Planting Works Too

If you want to plant broccoli in Seattle in spring, aim for late February through early April.
 
Start seeds indoors in February, then transplant seedlings out when they’re about four to six weeks old and daytime temps stay above 40°F.
 
Spring-planted broccoli in Seattle needs to finish before the summer heat arrives, so getting an early start is key.
 
Use row covers or cloches to protect young transplants from Seattle’s chilly spring nights.

3. Watch Your Variety

Not all broccoli varieties perform the same when you plant broccoli in Seattle, so choose carefully.
 
Fast-maturing varieties like ‘Calabrese’ or ‘Green Comet’ are great for spring planting because they finish quickly.
 
For fall planting, slower varieties like ‘Waltham 29’ or ‘Purple Sprouting’ thrive in the cool months.
 
Picking the right variety is half the battle when deciding when to plant broccoli in Seattle.

Why Timing Matters When Planting Broccoli in Seattle

Planting broccoli in Seattle at the right time is the difference between tight, tasty heads and bolted, bitter stalks.
 
Here’s what’s really going on:

1. Seattle’s Climate Is Broccoli Heaven

Broccoli grows best between 45°F and 75°F, and Seattle’s marine climate serves up those temps for months.
 
Our mild springs and long, cool autumns mean broccoli planted in Seattle at the right time rarely stresses.
 
Stress is what triggers bolting, that annoying process where broccoli flowers early and turns woody.

2. Heat Is the Enemy

If you plant broccoli in Seattle too late in spring, the summer heat will push your plants to bolt before they form good heads.
 
That’s why fall planting is so reliable here, the plants size up as the days shorten and cool down.
 
Once daytime temps start hitting the high 70s, broccoli in Seattle stops producing quality heads.

3. Daylight Affects Head Formation

Broccoli is sensitive to day length, and when you plant broccoli in Seattle, long summer days can work against you.
 
Fall-planted broccoli develops heads as days shorten, which is exactly what the plant wants.
 
This is another reason experienced Seattle gardeners lean heavily toward the July-August planting window.

How to Plant Broccoli in Seattle the Right Way

Once you’ve nailed down when to plant broccoli in Seattle, a few simple steps set you up for success:

1. Prep Your Soil

Broccoli is a heavy feeder, so work in plenty of compost before you plant broccoli in Seattle beds.
 
Aim for soil pH between 6.0 and 7.0, and make sure your beds drain well, because soggy Seattle winters can rot roots.

2. Give Them Space and Sun

Space broccoli plants about 18 inches apart when you plant broccoli in Seattle, and pick a spot with at least six hours of sun.
 
In our climate, a little afternoon shade in late summer actually helps transplants settle in.

3. Water and Feed Consistently

After you plant broccoli in Seattle, keep soil evenly moist and side-dress with compost or a balanced fertilizer a few weeks in.
 
Consistency is everything, dry spells followed by heavy rain can ruin head development.

So, When to Plant Broccoli in Seattle?

When to plant broccoli in Seattle comes down to two windows: plant broccoli in Seattle from mid-July to August for a fantastic fall harvest, or from late February to early April for a spring crop.
 
Broccoli thrives in our cool, moist climate as long as you avoid the summer heat and choose the right variety.
 
Time your planting right, prep your soil, and keep the water steady, and you’ll be eating homegrown broccoli in Seattle within a couple of months.
 
Happy planting!