By Julie Christensen
When it comes to large shade trees, few trees can compare to the red oak. This tree grows faster than most oak trees and has an open canopy. Mature urban trees grow 70 to 80 feet tall, while rural trees can grow even taller. The trees have glossy green leaves in the summer, followed by brilliant red fall foliage. Large acorns appear in late summer, providing food to squirrels and other wildlife. The bark of young trees is smooth and silver in color. As the tree ages, the bark develops ridges and darkens.
There are dozens of red oak species. Two of the most common in the U.S. are the Northern red oak and the Southern red oak. Northern red oak (Quercus rubra) grows throughout the Midwest and is a major tree in the Midwestern timber industry. The tree’s hard, durable wood is valued for flooring, furniture and timbers.
Northern red oak is hardy in U.S. Department of Agriculture plant hardiness zones 3 through 7. Southern red oak (Quercus falcata Michx) has similar attributes, but is found throughout the South and is hardy in USDA zones 6 through 10.
To identify the particular oak tree that you have, check out Identify Oak – The Major Oak Species of North America for photos and descriptions.
Caring for Red Oak Trees
If you’re looking for a low-maintenance, long-lived tree, red oak is definitely one to consider. These trees tolerate most soil types, so long as the soil is well-draining. The trees grow best in moist, acidic to neutral soil. If your soil pH is above 7.5, the leaves might yellow because of an iron deficiency. This problem is difficult to treat and can cause a slow decline of tree health. If you have alkaline soil, your best bet is to consider a different species, such as a bur oak or English oak. Plant red oaks in full sun and give them plenty of space because they will become large landscaping trees.
Water the trees regularly the first season as the roots become established. Older trees won’t need supplemental irrigation, except in drought conditions. Do not fertilize oak trees at planting time. You can apply a small amount of all-purpose fertilizer the following and subsequent springs if growth seems slow, but in general, red oak doesn’t need fertilizing, especially if the tree is planted in a fertilized lawn area.
Prune red oak trees annually to remove dead or diseased limbs, or any branches that grow vertically or rub against each other. Cut branches at the collar, which is the small bump between the trunk and the branch, and don’t apply ointments or wrappings. You can easily tackle pruning tasks while the tree is young, but consider hiring a professional to prune large, mature trees.
Pests and Disease
Red oak trees are susceptible to a number of insect pests and diseases, but most of them aren’t serious. The best way to manage minor diseases, such as powdery mildew and leaf spot, is simply to keep the tree healthy through regular watering and good pruning practices. Caterpillars, scale and leafhoppers sometimes infest red oaks, but birds and other natural predators usually control them.
Occasionally red oaks become infected with cankers caused by a fungus. These cankers cause white or brown growths on the bark. Prune out infected branches and disinfect your pruning tools by dipping them in a solution of one part chlorine bleach to 10 parts water. Once cankers reach the trunk of the tree, it usually can’t be saved.
Oak wilt is a serious fungal disease to which red oaks are susceptible. Infected trees first lose leaves at the tops of the tree. The lower leaves slowly die and drop and you might notice brown streaks in the wood. Consult a tree specialist if you suspect oak wilt. In most cases, the only remedy is to remove the tree. Do so quickly if you have other oak trees nearby because they are at risk of catching the disease, as well.
To learn more about caring for red oak trees, visit the following sites:
Red Oak from the Ohio Department of Natural Resources
Oak Diseases and Insect Pests from Clemson University Extension
When she’s not writing about gardening, food and canning, Julie Christensen enjoys spending time in her gardens, which includes perennials, vegetables and fruit trees. She’s written hundreds of gardening articles for the Gardening Channel, Garden Guides and San Francisco Gate, as well as several e-books.