Water most plants deeply and infrequently. When using a sprinkler, measure how many inches of water you apply by setting jars at intervals along sprinkler pathways. This will also tell you if the sprinkler gives even coverage. 

Remember soil type affects how much water is necessary. Water sandy soils more frequently than clay soil. To make sure you are delivering enough water to where it is needed, use a soil probe or shovel before you water to determine the extent of dryness. Repeat the process after watering to see how deeply the water has penetrated into the soil. 

Lawns. Use an overhead sprinkler. Water to a depth of at least 6 inches as soon as grass fails to spring up after walking on it. Avoid frequent, shallow waterings as they lead to shallow roots, which are far more susceptible to heat or drought. Aeration, or removal of soil plugs, helps send water to the root zone. Renting an aerator every other year or so also will help to reduce thatch build-up and combat compaction.

Vegetables, Bedding Plants, and Perennials. Water 6 to 12 inches deep every four to ten days for established plants. Don’t wait for plants to wilt before the next watering. Wilting slows growth and reduces crop yields.