Grow Great Tomatoes in the NW

Tips from an Avid Grower

by Kirsten DeLara, Master Composter/Soil Builder

Aussie Matina

Wanna grow tomatoes? While we all dream of yummy home grown tomatoes, local gardeners are often challenged by our cool spring temperatures. The secret ingredients are heat and healthy soil. Here are some tried and true techniques to create your own tropical tomato paradise.

Before you Plant

Pick a sunny spot. Select a location that gets eight hours of sun exposure — even better if it has radiant heat from sunshine reflecting off of a wall. Tomatoes love heat!

Heat the soil
. This step can be as simple as placing dark tarps or plastic over your vegetable garden. Raised beds will further increase soil heat.

Heat the air.
Warm air is critical so keep the heat close. If you just have a few plants, you can fill wine bottles with water to create a wall around each plant. You can also buy commercial “Wall O’ Water.” Or think larger—from simple cloches using PE pipe to a wood framed “house” covered in 4-6 mil plastic sheeting. Voila — instant greenhouse! Water-filled gallon jugs placed inside will increase heat gains.

Ready, Set, Plant

Now you’re ready to start working the soil. Remove the tarp and work in composted steer manure, compost and any remaining cover crops. Feed the soil, not the plant. Next, apply mulch or a soil cover to eliminate weeds, keep the soil warm, and reduce water loss from evaporation. A commercial option is “Planters Paper.” It is water-permeable, discourages slugs and disintegrates over the season. Make slits in the cover to plant through. Add a natural calcium source to reduce chances of blossom-end rot. This disease shows up as a black circle spreading from the bottom of a tomato and often occurs when water fluctuations inhibit the plant’s ability to absorb calcium from the soil. Watering more regularly and adding additional calcium should help turn things around.


Invite the bees. Attract a variety of pollinating bees by opening cloches or other structures on warm days and placing flowering pots, such as lavender and marigold, just inside. Or try your skills at hand pollination by brushing each flower lightly with an inexpensive electric toothbrush with frayed bristles. This mimics the pollinating vibration (sonication) of bumble bees. Remove covers completely when nights are warm. Keep the water off. To minimize risk of late blight (Phytophthora infestans) and Verticillium wilt, select disease resistant plants and use soaker hoses to keep water from splashing soil onto leaves. Reapply your cover before late summer rains. Finally, keep the garden tidy—remove any infected leaves or plants as soon as possible.


Sit back and savor the abundance of delicious tomatoes from your own natural garden. The results are priceless and all your neighbors will be jealous! For a list of my favorite tomato varieties, as well as tips on greenhouse structures, soil amending, and fall tasks, see the full article on Seattle Tilth’s Garden Almanac.

Delve deeper by taking a Seattle Tilth class, getting your own copy of the Maritime Northwest Garden Guide, Your Farm in the City, or call the Garden Hotline at (206) 633-0224 or send them an email at for more expert advice.

May Edible Plant Sale


Ready to get started? Come to May Edible Plant Sale and take your pick from a huge selection of edible plant starts perfect for summer gardens. It’s FREE and takes place on Sat. and Sun., May 4 and 5, 9 a.m.-3 p.m at Meridian Park in Wallingford.

Find over 50 varieties of tomatoes and 20 types of peppers! Try out heirloom varieties and peruse the extensive selection of culinary herbs, edible flowers and drought tolerant perennials. Be sure to check out the Seattle Youth Garden Works tomato tent for some hard-to-find gems that you probably won’t see at your neighborhood garden center.

Short on time? No problem — pick up a ready-made Garden to Go online. Get first pick of the plants at our Early Bird Sale or volunteer and get in for free. Check out our plant lists, see the schedule of educational presentations, live music and activities, and get some hot tips for easy shopping on the event page. Invite your friends on Facebook and share it on your wall. Thanks for your support!

3 responses to “Grow Great Tomatoes in the NW

  1. Pingback: Harden-Off Your Transplants for a Great Start | Seattle Tilth Blog·

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