t’s a common misconception that a tree’s roots are a mirror image of the aboveground canopy. In reality, an established tree’s roots usually extend well beyond the edge of the canopy, or drip line. Although some anchor roots may reach deep into the soil, most tree roots are concentrated in the upper 12″ to 18″ of soil. When watering established trees, provide a deep, soaking irrigation to the entire area beneath the tree canopy and extending several feet beyond the drip line. Ideally, you should moisten the soil to a depth of 10″ each time you water. To prevent rot, don’t apply water to the area directly around the trunk.