Browse nurseries for drought-tolerant plants. Native plants, such as rhododendrons, have adapted to the Northwest's typical rainfall patterns, and are thus not very drought-tolerant. Reduce evaporation from the soil by using plenty of mulch after planting. Be sure to keep the mulch away from the crowns of plants. Two to 3 inches of mulch are enough.
Plants prefer deep, less frequent watering over light, more frequent watering.
They grow deeper roots when the water soaks further into the soil. During the hottest days of summer, apply 1 inch of water a week to the lawn. Measure the height by placing tuna-fish cans on the lawn. For a list of plants for dry areas, take a look at the indispensable Sunset Western Garden Book. One of the many varieties of pelarganium, scented geraniums add a distinctive element to the garden, whether planted in containers or directly in the ground.