Quercus rubra (red oak) is one of the fastest growing oaks in Tennessee‚ growing more than 2 feet per year after establishment in the landscape․ It provides good fall color in its young age‚ with new leaves ranging from red to russet․ Mature trees are 60 to 75 feet tall‚ making it adaptable as a shade tree that has good fall color․ It is one of the best choices for the USDA plant hardiness zones 4 through 8 that cover all of Tennessee․
Why Red Oak Works Here․
Tennessee has clayey soils‚ humid mid-summer‚ and large changes in temperatures during the winter‚ so generally the conditions are not very hospitable for tree growth‚ but the red oak can grow in these soils and also tolerates a wide range of pH levels․ It can handle the acidic soils you get in East Tennessee as well as the more alkaline pockets you sometimes run into in Middle Tennessee․ Once established‚ it's tolerant of short dry spells․
It does have some specific habitat requirements: red oak usually prefers well-drained loam soils with a constant supply of moisture and does not do well on wet‚ waterlogged soils․ If you have a low spot in your yard that puddles after a rain‚ this is not a tree to plant there․ Plant it higher or drain the area better․
So what is it that makes the fall color so reliable?
Unlike most other maples‚ which require a certain number of days of freezing temperature to produce their most brilliant fall foliage‚ red oak turns russet red to brick red in autumn regardless of temperature․ It turns late in the autumn (late October to mid-November in Tennessee) so it is useful in the landscape in which a long fall color season is desired after the fall color has passed‚ such as dogwood and sugar maple trees․
The basic textbook answer is that the green chlorophyll that gives leaves their color breaks down when days grow shorter and nights grow cooler and the deep red shades produced by anthocyanins that already exist in leaf tissue take over․ The red oak produces more anthocyanin than many other oaks do‚ which is responsible for red oak's more vivid fall color compared to white oaks that only exhibit the more subtle bronzing effect․
Soil acidity‚ sunlight and summertime drought stress can all affect the fall color․ A tree in full sunlight who received even moisture throughout the growing season will almost always outdo a similar tree stuck in partial shade the whole summer‚ or one that goes through a drought․
Planting: Timing and Technique
In Tennessee‚ autumn‚ the period between early October and the beginning of December is the best time to plant trees․ Planting any time in fall before the frost gets in the ground gives the roots of the plant several months to grow before spring's growing season․ The second best time to plant is early in the spring after the earth can be worked but before the buds break․
The planting hole should be two times as wide as the root ball diameter and no deeper than the growing depth in the nursery․ Planting too deep is one of the most common mistakes in the planting of oaks‚ and can stunt or kill them; the root flare (where the trunk flares out to become roots) should be at or above grade level․
Backfill with native soil․ Oaks do best with their roots growing into native soil rather than a pocket of compost or bagged topsoil created by adding too much amended soil around the rootball․ Water well at planting and keep the root zone of new plants evenly moist but not wet and soggy during the first year․
Spacing and Placement
With a canopy width of 40 to 50 ft at maturity‚ it should not be planted closer than 25 ft (7․6 m) from a house foundation‚ driveway‚ or septic system‚ and 20 ft (6․1 m) from other large trees․ On a small inner-city lot‚ it is not a tree for the future unless you are prepared to give it room to fill out to its mature size․
It is not a tree which tolerates heavy pruning‚ therefore the use of it as a feature tree is best considered with its ultimate size in mind rather than periodically pruned to smaller dimensions․
Ongoing Care
Red oak is easy to grow once established (usually by the second or third year)‚ requiring little maintenance except for:
Water
Water once a week for the first two years until the plant is well established․ Water more frequently in extreme summer heat; after two years‚ rainfall is usually sufficient for Tennessee except during long-term drought․
Fertilizing
Mature red oaks require no fertilizer‚ provided the soil is reasonably fertile․ If growth is poor and foliage is pale‚ use slow-release tree fertilizer in early spring․
Pruning
Prune when dormant to shape tree structurally in late winter․ Remove crossing branches‚ dead wood or competing leaders early in life while tree is molding its form․ Spring and early summer months (around April to July) should be avoided for pruning because freshly made stumps will attract the beetles responsible for spreading the oak wilt disease․
Pests and diseases
The most serious disease among these is oak wilt‚ caused by a fungal pathogen spread by sap beetles and root systems․ Avoid pruning while sap beetles are at their height of activity (summer)․ Gypsy moth caterpillars and oak skeletonizers are also present‚ but they rarely cause lasting damage on established trees․
What Red Oak Brings to Your Landscape Beyond Looks
Acorns of red oak are eaten by deer‚ squirrels‚ small mammals‚ turkeys‚ and many songbirds․ Red oaks support hundreds of species of native caterpillars that form an important food source for many birds while breeding․ Few ornamental landscape trees pull this much ecological weight․ If you're looking to create a visually and ecologically appealing yard‚ a red oak is one of the top choices you can make․
These leaves are better left within the garden beds or under the tree‚ as they break down relatively slowly and are good free mulch that helps improve soils․
Getting Started
TN Nursery ships well established red oak saplings that are much more likely to take to their new location than younger saplings․ They are much more established than saplings sold as bare root stock․ And since the red oaks take so long to reach maturity‚ and since our saplings are already so established and so healthy‚ you can shave real years off the time before you will stand under real shade and real fall color․
If your red oak is planted and allowed to become established‚ it will likely outlive you and be one of those trees a Tennessee property is remembered for․
