Set a garden hose at a slow trickle for 15 minutes (20 minutes for smaller trees). A watering of once per week should be adequate.
Spread mulch near trees. It helps prevent evaporation from the soil and prevents water from running when the ground is hard.
Pay particular attentention to trees on boulevards near construction zones. Road work can stress a tree.
Bigger trees in yards also suffer from stress. Water a larger tree with a sprinkler. Set out a coffee can near the tree. When the can has an inch of water in it, turn off the sprinkler. A watering of once per week is adequate.
