An easy way to remember water needs for various trees is 10 gallons per inch of trunk diameter. The trunk diameter should be measured at about two feet from ground, and the general formula: tree diameter x 5 minutes= total watering time.
For example, using a hose at medium pressure usually takes about 5 minutes to obtain 10 gallons of water. Therefore, if you have a 5” diameter tree, it should receive 50 gallons of water; multiply by 5 minutes to equal total watering time of 25 minutes.
Water should be distributed evenly under the drip line of the tree, and not necessarily against the trunk. Also, trees should be watered three times per month during April- September.