A regular program of maintenance is required for best results with any tree or shrub. This program includes irrigation during the early years, core aeration, mulching, fertilization, pruning and regular inspection for disease and insect problems. Watering woody ornamentals depends on the species and the soil.
Some plants tolerate dry conditions better than others.
A tree growing in a fertile, well-drained sandy loam may become established in a year or two. This tree would require little supplemental irrigation. A shallow-rooted tree planted in a poorly drained, heavy clay may require supplemental irrigation for several years. During the first 4 to 10 years after planting, trees and shrubs may require supplemental watering. The most critical season for supplemental irrigation is usually during summer.