You want to keep you trees healthy and well-watered. Bu, overwatering is just as much of a problem as under-watering a tree. Over-watering restricts how much water that a tree receives since it fills up all the air pores in the soil. There are signs, however, to help you determine whether you are over-watering your trees. If you notice any of these signs, stop watering your tree for a while and wait until the soil around the tree is actually dry.
Over-damp soil is the first sign that you are over-watering your tree. If you place your hand on the soil, and it is completely wet, then you don't need to water your tree for a while. Sometimes, however, the top soil is dry, but the underlying layers are not. Try digging up about 2 inches of your soil, and check to see if that area is damp. If it is, then your tree has enough water. Invest in a water gauge. These gauges have a dry, moist and wet section, and they stick in the soil around your trees and plants. Water gauges are different heights, so look for a long one that will dig deep into your soil.
Leaves are another good sign of whether you are over-watering the soil. Leaves become brittle when they have too much water. They will more than likely still be green, but they will easily break apart when you touch them. Besides established leaves, look at new leaves. If you are watering too much, these young leaves are lighter in color, usually either yellow or very light green. Leaf trouble is associated with the roots of the plant becoming clogged with wet soil. This stops the oxygenation process, effectively drowning the roots below ground. If you see changes in your leaves like this, immediately stop watering your tree. Since leaves changing color or dying are signs of other diseases and insect infestation, you should rule out over-watering first. Check other trees and shrubs in the area. If they all have the same signs, then it's probably not a case of over-watering.
Leaves are usually the most obvious example that your tree is suffocating. But, you may also see new shoots dying before maturity. This also stems from the roots being unable to use all the oxygen in the ground and not getting enough oxygen. Another sign is mushrooms, moss and algae growing around the tree. These plants require constantly wet soils to grow, and they signal that the soil is extremely and constantly damp.