Plants require varying amounts of supplemental water, depending on the type of plant, growing conditions and amount of rainfall. Young plants need more irrigation than older plants that have developed an established root system. Monitoring the rainfall and amount of water you supply through irrigation helps determine if the plant's water needs are met. Plants also provide physical signs if they are running low on water.

The plant's leaves often show the first signs of too little water. They begin to wilt or droop from lack of moisture. Grass blades wilt and fail to spring back up when stepped on. You may notice shiny plant leaves turning dull. Over time the wilting becomes more pronounced and sometimes becomes permanent. Leaves and stems may turn yellowish or brown with prolonged lack of water. Some plants with drought stress appear scorched along the leaf edges.