When do you plant tomatoes in Seattle?


When to plant tomatoes in Seattle? You’ll find the answer just below.


Here’s some key information about when (and how) you should plant your tomatoes in Seattle for the best results.


Firstly, it’s highly advisable, if not imperative that you choose tomato varieties that will do well in Seattle.

The following varieties listed under “Best Tomatoes for Seattle”, at least many of them, are available to buy as starter plants from the Port Townsend Farmer’s Market, Chimacum Farmer’s Market, and others. Otherwise, you could try your local plant nursery or garden center.



Best Tomatoes for Seattle


Slicing tomatoes that do well outdoors in Seattle:

Country Taste, SunRay, Celebrity, Siberian, Willamette, Stupice, Glacier, Siletz.


Slicing tomatoes that do well in a greenhouse in Seattle:

Mr. Stripey, Taxi, Charger, Moskvich, Bella Rosa, Creole, Jaune Flamme, Country Taste, Clermon, Bush Goliath, Goliath.


Roma tomatoes – best grown in a greenhouse:

Golden Rave


Cherry tomatoes that do well outside in Seattle or in a greenhouse:

Sun Gold, Sweet Million, White Cherry, Sun Cherry, Golden Grape, Sun Gold, Super Sweet 100, Sakura, Pink Bumble Bee, Snowball, Sweet Treats, Tumbler, Gold Nugget, Red Alert, Sweet Hearts, Toronjino.


Heirlooms – all of these heirlooms are best suited to a greenhouse in Seattle:

Mortgage Lifter, SunRay, Cody’s Rainbow, Cherokee Purple, Big Beef, Amana Orange, Brandywine, Black Brandywine, Texas Star, Coeur di Bue, Aunt Ruby’s German Green beefsteak, Abe Lincoln, Lemon Boy, Geronimo, Ananas Noire.



When to Plant Tomatoes in Seattle



What Fertiliser is Best for Tomatoes?

Each week, give your tomato plants some fertilizer.

Early on in the growing season, you’ll want to give your tomatoes a fertilizer that is high in nitrogen. Nitrogen is essential for the growth of the foliage – the leaves and the stem. 

One that I use is Osmocote Smart Release. It has a macronutrient (NPK) ratio of 15-9-12. Additionally, it comes with nine other micronutrients.



 Osmocote Smart-Release Plus Fertilizer (with 12 nutrients)



At or around mid-season and your tomatoes will benefit much more from a fertilizer that is high in potassium (K). Potassium is essential for healthy fruit growth. I like the Miracle-Gro Tomato Fertilizer with its 18-18-21 NPK ratio.


Miracle-Gro Tomato Fertilizer





When to Plant Tomatoes in Seattle?

The key here is to plant tomatoes in Seattle after the last frost date in springtime. Typically, the final frost date in Seattle is March 17. Plant your tomatoes towards the end of March or beginning of April and the chances are you’ll not have any problems with frost. 

The soil temperature should be at least 55 degrees F for best results. If the soil temperature is below 50 degrees F your tomato plants will not develop.

On the other hand, the soil temperature should not rise above 85 degrees F. That’s a rarity in Seattle. In fact, early on in the growing season, the soil temperatures struggle to rise above 50 degrees.

This is why it’s good practice to grow your tomatoes in a greenhouse. Of course, not everyone has the luxury of a greenhouse. So, and in which case, you can try raised beds.

Raised beds, particularly when well incorporated with yard compost or manure, will enjoy higher soil temperatures than the soil in your Seattle garden. Nothing fancy is called for here. Simply layer up your soil level by ‘borrowing’ soil from elsewhere in your garden.

You can, if preferred, grow your tomatoes in containers. Fifteen- to 20-gallon containers are plenty big enough for tomato plants. For cherry tomato plants and other determinate varieties, five-gallon containers are ideal.

Each of these methods offers a valid way in which to maximize your soil temperature.

How about air temperatures for tomatoes?

Ideally, you’ll want air temperature to be between 65 and 85 F. That’s during the day. At night, the optimal air temperature would be 55-65 F.

If the air temperature rises above 85 F it inhibits pollination. That would mean you’ll have plenty of blossoms but zero fruit.

Fortunately, (or unfortunately, depending on your point of view) Seattle temperatures never get this high. The hottest months in Seattle – July and August – typically enjoy air temperatures of up to 73.4°F.

If, though, your tomatoes are greenhouse located do be sure to keep a careful eye on the temperature variations.


In need of stakes or cages for your tomatoes? Very likely that you are!

These 6ft-long bamboo stakes are ideal for tomatoes. Stakes at 6ft tall may seem too high. However, most indeterminate tomato plants reach 8-10 feet in height. Further, at least 1 foot of each stake will be in the ground, leaving you 5 feet to play with.



When to Plant Tomatoes in Seattle
 6ft-Tall Natural Bamboo Stakes for Tomatoes




For tomato ties you can’t go wrong with these Velcro-style ties:

 Velcro Ties for Tomatoes etc.




When to Plant Tomatoes in Seattle



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