In North America, two different species of red oak grow well to provide shade in spacious landscapes. Northern red oak (Quercus rubra) and the southern red oak (Quercus falcata) display different environmental tolerances. Know which species you grow before starting a watering regimen.
Oaks are transplanted when young to avoid disrupting the development of their initial deep taproots. After planting, both northern and southern red oaks benefit from irrigation to maintain an evenly moist soil. Avoid dry and soggy soil conditions.
Once the trees are about 10 years old, their water needs differ. Northern red oak appreciates evenly moist soil and tolerates only light droughts. The southern red oak demonstrates extensive drought tolerance and benefits from irrigation in droughts, but its health isn't diminished by dry soil.
The U.S. Forest Service notes that northern red oak grows better in cool, mulched soils that are moist. If you want either type of oak to grow more quickly, irrigate to maintain a moist soil, especially in summer. Southern red oak needs less water to remain healthy.
Water oak trees as needed to keep the top 24 inches moist. Overly wet soil leads to fungal rot and canker problems. Roots of trees extend 20 to 50 feet beyond the branch tips, so don't just water around the trunk.