Keeping plants healthy requires knowing when they have had too much or not enough water. The variety of the plant, soil conditions and sun conditions all play a part in how much water a plant needs. Plants located in a humid environment may need less water than those located in dryer conditions. Indoor plants have differing needs than those located outdoors.
Stick the tip of your index finger 1 inch into the soil of wilted plants. If the soil crumbles and feels dry, the plant needs water. If the soil feels soggy, the plant has been over-watered.
Examine the plant leaves for drooping and a yellowish color. Drooping and yellow leaves normally mean the plant's roots have rotted from excessive watering.
Inspect the plant for brittle and brown leaves. This symptom means under-watering has occurred, causing the roots to die. If the soil does not appear dry, rock salt from a water softener may be the cause of brown leaves.
Check for dropped leaves. Over-watered plants have limp leaves that fall from the plant, while under-watered plants lose brittle leaves.