A general rule for mature trees is to deep water once or twice a month for about 2 hours. This can be done with a slow water flow from a garden hose or a soaker hose. Make sure the soil is absorbing the water and it is not running off the down the street. Place the hose about one half to three quarters the distance between the stump and the end of the drip line. The finer roots that absorb the water are nearest to the end of the drip line and are within the top 12 inches of soil. Younger or newly planted trees will need additional watering depending on specie and existing environment.
Add mulch within the drip line.
Place mulch within the drip line of the tree about 2 to 4 inches deep. Keep the mulch away from the trunk of the tree. The mulch should be organic (wood chips, bark, or leaves). The mulch will conserve soil moisture and moderate soil temperatures.
Only prune out the dead wood or damaged branches. Do not remove any live branches at this time and do not fertilize. Try not to disturb the soil within the drip line. For example don’t let vehicles park under the tree, try and keep animals away from trunk, etc.