When To Plant Herbs In Seattle

The best time to plant herbs in Seattle is right after the last spring frost, which usually falls in late March or early April, and again in late summer for a fall harvest.
 
Knowing when to plant herbs in Seattle can feel a little tricky because our maritime climate is unique, with mild winters and cool, damp springs.
 
But once you get the timing down, you’ll have thriving basil, cilantro, and rosemary all season long.
 
In this post, we’ll break down the exact months for planting herbs in Seattle, what to start indoors versus outdoors, and how to work with our specific weather patterns.
 
Let’s dig into the dirt and get your herb garden growing.
 

When To Plant Herbs In Seattle: Spring Timing Explained

When to plant herbs in Seattle in spring really depends on whether your herbs are cold-hardy or frost-tender.
 
Seattle’s last frost date is typically around March 20th, but it can stretch into mid-April in cooler microclimates.
 
So if you’re asking when to plant herbs in Seattle, the safest rule is to wait until soil temps reach at least 50°F for hardy types and 60°F for tender ones.
 

1. Cold-Hardy Herbs: Late March To Early April

When to plant herbs in Seattle for cold-hardy varieties like parsley, chives, thyme, and oregano is as soon as the ground is workable.
 
These herbs can handle light frosts and cool Seattle rain without a problem.
 
Planting herbs in Seattle in late March gives them a head start before the warmer weather kicks in.
 
You can also sow these directly into the garden, no need for indoor fuss.
 
They’ll germinate fine in the cool, damp soil that Seattle is known for.
 

2. Frost-Tender Herbs: Mid-April To Early May

When to plant herbs in Seattle for basil, dill, and cilantro is a different story because these guys hate the cold.
 
Wait until the danger of frost has fully passed, usually by April 15th or even May 1st if you live near the water.
 
For the best results, start these herbs indoors about 4-6 weeks before your intended transplant date.
 
If you direct sow, keep an eye on the forecast and cover them if a surprise cold snap rolls in.
 
The key to knowing when to plant herbs in Seattle with tender varieties is patience, don’t rush it.
 

Planting Herbs In Seattle: Fall And Winter Options

Most folks only think about spring, but when to plant herbs in Seattle also includes a fantastic fall window.
 
Our mild autumns and wet winters are perfect for cool-season herbs.
 
Planting herbs in Seattle in late August through September gives you a second crop of cilantro, dill, and arugula.
 

1. Late Summer Sowing For Fall Harvest

When to plant herbs in Seattle for a fall harvest is around August 20th to September 10th.
 
The soil is still warm from summer, which helps seeds germinate quickly.
 
Then as the weather cools, the herbs slow down and develop sweeter, more tender leaves.
 
This is a pro move for planting herbs in Seattle because you get two harvests in one year.
 
And since Seattle doesn’t get a hard freeze until December or January, you’ll often harvest well into November.
 

2. Overwintering Hardy Perennials

When to plant herbs in Seattle for perennials like rosemary, sage, and mint is best done in early fall.
 
This gives them time to establish roots before the rainy season hits hard.
 
In Seattle’s mild winters, these herbs will survive just fine outdoors, especially if planted against a south-facing wall.
 
You can also plant them in containers and move them to a sheltered spot if we get an unusually cold spell.
 
So when to plant herbs in Seattle for perennials, fall is your golden window.
 

Planting Herbs In Seattle: Indoor Starts And Microclimates

If you’re tired of guessing when to plant herbs in Seattle, consider starting everything indoors.
 
This takes the guesswork out of frost dates and gives you a huge head start.
 

1. Indoor Sowing In February And March

When to plant herbs in Seattle indoors is six to eight weeks before your last frost date.
 
For most herbs, that means February 1st through March 1st is perfect.
 
Use a seed-starting tray with a heat mat for best germination rates.
 
Seattle winters are dark and cloudy, so you’ll definitely need a grow light.
 
Once the seedlings have two sets of true leaves, harden them off by putting them outside for a few hours each day.
 
This is the most reliable way to answer when to plant herbs in Seattle without stressing about the weather.
 

2. Working With Seattle’s Unique Microclimates

When to plant herbs in Seattle can shift by a week or two depending on your neighborhood.
 
If you live near Puget Sound, you get milder temps and can plant earlier.
 
If you’re in the Eastside hills or more inland areas, frost lingers longer, so delay planting.
 
A simple soil thermometer is your best friend here.
 
Check it each morning, and you’ll know exactly when to plant herbs in Seattle no matter where you are.
 

So, When To Plant Herbs In Seattle?

When to plant herbs in Seattle is all about matching each herb’s tolerance to our regional weather patterns.
 
You can plant hardy herbs in late March, tender herbs in mid-April, and cool-season herbs again in late August.
 
For perennials, early fall is your best bet to get them established before winter rains.
 
And if you start indoors, you can begin as early as February for a huge advantage.
 
So when to plant herbs in Seattle really boils down to knowing your frost dates, monitoring soil temps, and being patient with the tender guys.
 
With this guide, you’ll have fresh herbs from your Seattle garden almost year-round.
 
Happy planting.