The watering needs of plants depend on the type of plant you're growing, whether you are growing them in pots or outside. If they are growing outside, you have to pay attention to the type of soil and the weather. To know whether or not you are watering them too much, you have to know the signs of over watering, which is sometimes hard to discern.
Yellow, Wilting or Drooping Leaves
One of the first signs of overwatering is that plants look sickly; their leaves begin to turn yellow, then they droop or wilt. Plants breathe through their roots. If soil is saturated with water, the plant can die from a lack of air. Plants are weakened by soil that is constantly too wet, leaving them prone to attacks by pests and disease.
Make sure your planting pots are properly drained. Regularly empty water that has drained from the bottoms of your growing pots.
Slow Growth or Brown Leaves
If your plants are not growing at all or if the leaves are turning brown, you might be over watering. As you spot these signs and other symptoms, remember that the consequence of under and overwatering are often the same. What might appear to be overwatering might mean also mean you're not giving your plants enough light or fertilizer, or maybe they're too cold. You can sometimes save an overwatered plant by removing it, wrapping the root ball in newspapers or paper towels and letting it dry until it is barely moist. Repot it, then water when the top couple of inches of soil are dry.
Fuzzy Mold and Greenish Soil
Fuzz growing on your plant or greenish-looking soil are signs of mold and algae, a common consequence of overwatering. Mold and algae thrive on moisture. If the soil feels damp, the plant does not need water. Water in the morning, because if you water at night, the foliage will be damp at night, an invitation to molds and fungi. Only water a plant if the surface of the soil feels dry. Plants in small containers need to be watered more often than plants in large tubs.
Dig down and check the roots. If they are rotten or rotting and smell awful, you are likely overwatering the plant. Ferns, African violets and some other plants like moist soil. Dry-soil plants, cacti and succulents do not need as much water, and their roots are more prone to over watering.If you plant outdoors, choose plants that are native to your area. They've had thousands of years to get used to your soil, weather and rainfall. To save a plant with root rot, remove it and rinse the roots. Cut away the rotted roots and replant. If your surgery was major, remove some of the foliage.