Many local landscape plants are more drought tolerant than most people think. Often people water their plants and gardens 30-80% more than they need.
On the other hand, newly planted plants, and especially trees and large shrubs need more water for the first year or two. Most perennials and smaller fast growing shrubs need extra water for 6-8 months, especially in the summer.
For most plants the best time to plant is in the fall or early winter so that roots can establish over our rainy season. Of course, most winters we don’t really get too much rain so additional watering is necessary.
Generally, if you want fast growth initially, water more, but when the plants get larger cut back on the watering. This will restrict future growth and eliminate a lot of unnecessary pruning and trimming. Download Low Water Plants Take Along List(PDF File, 6 pages, 292 K)