How to Properly Water Your Trees | Arbor Day Foundation

The best way to determine when trees need water is to check the soil. What you’re aiming for is moist — not soggy — soil. In the absence of rain or moisture, check the soil with a garden trowel to a depth of two inches. If the soil is dry to the touch, your tree needs water.

The rule of thumb for established trees is 10 gallons of water for each inch of the tree’s diameter.

Slow and deep is your best bet, which is why drip lines are the preferred method of watering (although spray from a garden hose will certainly work). Drip irrigation also loses less water to evaporation compared with overhead watering or sprinkler systems.

Allowing the soil to completely dry out — or allowing it to stay soggy — will result in a tree that is stressed and therefore more prone to disease and infestation.

Don’t forget to water your trees in the winter during dry spells. Just because they are dormant doesn’t mean your trees aren’t growing. Water when air and soil temperatures are above 40 degrees F and when there is no snow cover.