Live Oak Introduction
A large, sprawling, picturesque tree, usually graced with Spanish moss and strongly reminiscent of the Old South. Live oak is one of the broadest spreaders of the Oaks, providing large areas of deep, inviting shade. Live oak is the state tree of Georgia.
Reaching 60 to 80 feet in height with a 60 to 100-foot spread and usually possessing many sinuously curved trunks and branches, live oak is an impressive sight for any large-scale landscape. An amazingly durable American native, it can measure its lifetime in centuries if properly located and cared for in the landscape. It is also often wrongly planted in small landscapes and right-of-ways where it is doomed to heavy pruning and ultimate removal.
The live oaks scientific name is Quercus virginiana and pronounced like KWERK-us ver-jin-ee-AY-nuh.
The tree's most used common name is Southern Live Oak and in the family Fagaceae. It grows in
USDA hardiness zones 7B through 10B, is native to the North American south and generally available in many areas within its hardiness range. The oak is generally used in wide tree lawns but adapts well in large parking lot islands. It is a magnificent specimen tree in open landscapes.
Michael Durr in "Manual of Woody Landscape Plants" says it is a "massive, picturesque, wide-spreading, evergreen tree with magnificent horizontal and arching branches that form a broad rounded canopy; a single tree constitutes a garden."
A Botanical Description of Live Oak
As I have mentioned, live oak has a moderate height but a spread to 120 feet. The live oak crown uniformity is a canopy that is symmetrical and with a regular (or smooth) outline and all individuals have more or less identical broad crown forms.
A live oak's crown approximates round but has a definite look of spreading vertically. The crown can be considered dense but its growth rate is medium to slow which means that it can only become a prime tree specimen over many decades.
Live oak branches will continuously droop as the tree grows and will require pruning for vehicular or pedestrian clearance beneath the canopy. This is why a small urban median between moderately wide avenues will make for problems. The oak does have a showy trunk and should be grown on a single leader with substantial height.
The live oak leaf is thickly green and persistent through the winter. The leaf arrangement is alternate, the leaf type is simple and the leaf margin is entire.
Managing a Live Oak in the Landscape
A live oak tree will grow in part shade/part sun and in full sun. It tolerates many soils including clay, loam, sand, acidic, alkaline and occasionally wet but best on well-drained soils. The tree has a high tolerance of drought, a high tolerance of salty atmosphere and a moderate tolerance for salt in the soil.
You will need to prune this tree regularly to develop strong structure when in a managed landscape that has vehicular traffic. The tree is extremely resistant to breakage and will not be a problem in any but the strongest of storms.
Live oak is usually pest-free. Occasionally mites infest the foliage, but they are of little concern in the landscape. There is some concern for a newly discovered Texas live oak decline.
Galls cause homeowners much concern but should not. These trees "suffer" with many types of galls which can be on the leaves or twigs of Quercus virginiana. Most galls are harmless so chemical controls are not suggested.
Live Oak In Depth
Once established, the live oak will thrive in almost any location within its natural range and is very resistant to wind and its resulting damage. Live Oak is a tough, enduring tree that will respond with vigorous growth to plentiful moisture on well-drained soil.
Like other oaks, care must be taken to develop a strong branch structure early in the life of the tree. Be sure to eliminate multiple trunks and branches which form a narrow-angle with the trunk as these are likely to split from the tree as it grows older.
Be sure that an adequate landscape area is given to live oak as roots will grow under curbs and sidewalks when planted in confining soil spaces. When visiting large southern coastal cities (Mobile, Savannah) you will these trees thriving in these urban settings and their ability to lift sidewalks, curbs and driveways. This is the cost many are willing to pay for a live oak urban forest.
One of the biggest problems with live oak in cities, towns and private landscapes is e lack of pruning. This tree can live for a very long time and it is important to develop proper trunk and branch structure early in the life of the tree. Following planting in the landscape, prune the tree each year for the first three years, then every five years to age 30. This program will help ensure that the tree develops into a strong, long-lived fixture in the community, and will help develop the 14 to 15 foot tall vehicle clearance needed for planting along city streets.
Dirr, Michael A. "Manual of Woody Landscape Plants Their Identification, Ornamental Characteristics, Culture, Propogation and Uses." Bonnie Dirr (Illustrator), Margaret Stephan (Illustrator), et al., Revised edition, Stipes Pub Llc, January 1, 1990.