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.