As you apply water this winter, allow the water to soak in slowly to a depth of 12 inches. Water when the ground is not frozen and the temperature is over 40 degrees. Since winter watering is more labor intensive to you, apply the water where it counts the most, in the root zone. Consider that established trees have roots that go out at least as far as the tree is tall and usually further. It is in the “drip line” and just beyond where most of the water should be applied. The “drip line” is an imaginary vertical line that is perpendicular to the longest side branches of the tree and perpendicular to the ground. Water applied at the tree trunk base is wasted because there are no water absorbing roots there.
Watering recently planted trees and shrubs is a different story. Their roots do not go out as far yet. In this case you will want to water the root ball zone and just beyond. The aim is to water where the roots are.
Keep in mind that even when we get rain, trees and shrubs planted close to the foundation and under eaves may still need watering. Located in these areas, they receive little precipitation and they lose more moisture than other plants because of their proximity to the structure and reflected heat from the walls.
Ray Ridlen is an agriculture/horticulture educator for the Oklahoma County Extension Service. His column addresses frequently asked horticulture questions. For more information, call 713-1125.