Despite its rainy reputation, the Puget Sound area typically gets only 3 to 4 inches of rain for the entire summer. Some plants in your garden need an inch of water a week or more during this time.
The objective of good irrigation is to apply water carefully and slowly so that it wets the entire root zone. Quick, light sprinkling will not do the job. Frequent, shallow watering leads to shallow roots, and shallow roots lead to more rapid stress under dry or hot conditions. Water less frequently: once or twice a week but deeper. Take a trowel and dig down several inches and see whether water has penetrated to that level. Try to avoid watering from above the plant: Getting water on the leaves can encourage fungal diseases.
Consider adding mulch to your landscape. Mulch will help retain moisture, control weeds and contribute to healthy soil. WSU recommends arborist wood chips. See WSU publication FS160E, “Using Arborist Wood Chips as Landscape Mulch”, available at pubs.extension.wsu.edu, for more information.