Tomatoes are easy to grow in Puget Sound, if preferred conditions are met and our climate considered. The following guidance is based in part on our growing experience at our King County Master Gardener Demonstration Gardens.
Choosing Transplants and Hardening Off

Select short, sturdy plants and avoid those that are tall and leggy. There are two basic types of tomatoes. Determinate varieties are bush-like with fruit that ripens over a 4 to 6-week period, while indeterminate varieties are vine-like and continue to grow and produce tomatoes until the end of the season. Dwarf indeterminate tomatoes are a recent introduction that provide a long season of tomato production on a shorter and stockier plant. We’ve grown these in our Bellevue Demonstration Garden and found them to require less staking than traditional indeterminate tomato varieties.
Prior to planting out, gradually condition (harden) the plants to the outside weather conditions over the course of a week or so. Start with just a few hours in a partially sunny area, bring them in at night, and increase their time outside each day.
Location, Planting, Staking and Watering
Determinate tomatoes may need only minimal staking. Indeterminate tomato plants can get very large and will need staking, caging or trellising. Install the stakes or large cages at the time you plant the tomatoes. Tomatoes need about one inch of water a week. If tomatoes are in the ground, water thoroughly at the base of the plant twice a week. Tomatoes in containers may need more frequent watering. Never use overhead irrigation, as wet leaves cause the plant to be susceptible to disease. Plants that are well spaced and staked also reduce the opportunity for disease to take hold.
Weeding and Pruning
Ripening Fruit
Common Problems
Blossom End Rot (BER) causes a soft, dark lesion on the bottoms of ripening tomato fruit. It is most prevalent in Roma-type tomatoes, but can occur with many varieties. BER is considered a nutritional disorder due to lack of calcium uptake, but in a practical sense the cause is usually irregular watering. To avoid problems, have your soil tested to ensure that it contains appropriate nutrients and pH and keep plants adequately watered. Use a thick organic mulch around plants to help maintain soil moisture.
Physiological Leaf Roll is a common cosmetic issue seen early in the season, but does not impact fruit production or the health of the plant. Some varieties are more susceptible than others. Ensure adequate watering, and avoid over-fertilizing and over-pruning of young plants.
Catfacing is a development disorder that causes fruit to appear puckered, lumpy, or zippered. It is usually limited to early fruit or fruit developing during cool periods. High levels of nitrogen may increase the problem: Do not over-fertilize.
Cracked Fruit is most common when significant rainfall follows a period of dry weather. Sudden, rapid growth during fruit ripening causes the tomato to outgrow its skin. Mulching and regular, even watering can reduce cracking. Harvesting fruit in advance of forecasted rain is also advisable.
Sunscald causes soft white or yellow spots on fruit exposed to south-facing sun. Some varieties are more susceptible, simply because they produce less abundant foliage. Avoid pruning of upper leaves from tomato plants and cover plants or fruit with lightweight shade cloth if needed.
For more information about tomatoes, including helpful photographs, see WSU publication FS145E, “Growing Tomatoes in Home Gardens”, available as a free download at pubs.extension.wsu.edu. You’ll also find many other vegetable and home gardening publications there. Visit our demonstration gardens during the growing season. You’ll find a location listing at www.mgfkc.org/resources/demonstration-gardens
Additional Master Gardener Tip Sheets, including “Gardening Websites” and “Gardening Publications” are available at kingcountymg.org/gardening-tip-sheets. Also see WSU’s “Gardening in Washington State” at gardening.wsu.edu
Feature image by Axel Mellin.
CLH 12/20/19
WSU Extension Master Gardener Program * 206-543-0943 * king.MG@wsu.edu * kingcountyMG.org Center for Urban Horticulture * Box 354115 * Seattle WA 98195-4115 Extension programs and employment are available to all without discrimination. Evidence of noncompliance may be reported through your local Extension office.
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