Check for water waste. Rooting Out the Answers Remember, you're not watering plants. You're watering their roots. That's where plants drink. The key is understanding how plants absorb water.
Annuals usually have roots that thrive in the top twelve inches of soil.
Trees, shrubs and perennials have root systems that can go down a few feet or deeper and extend two to five times the branch spread. Lawns have very shallow roots that are usually not more than six inches deep. Timing Is Everything Don't water until plants need it or you'll cause problems. You'll know when to water just by observing the condition of the plants and soil. Water annuals only when the top inch or two of soil are dry.