Water your plants in the morning, to conserve water and reduce evaporation. Frequent, deep watering is better than frequent, shallow watering, since deep watering promotes deep root growth. For best results, deep-water trees and shrubs once or twice a week and flowers two to three times a week. Most plants need 1 inch of rainfall per week. Pay attention to how much falls from the sky and water accordingly. If you have an automatic irrigation system, consider installing a rain sensor that adjusts for rainfall.