Live oak (Quercus virginiana) is one of the most well-known trees found in Southern landscapes. While it is adaptable to all regions of South Carolina, it reaches its full development only within the warm, humid environment of its natural range (USDA Zones 8-10). Live oak can tolerate cold extremes in the Piedmont but not in the mountains where it grows slowly and commonly suffers from ice storm damage.
Live oak is a massive, picturesque, and wide-spreading evergreen tree with large, horizontal, and arching branches that give this oak its unique shape and distinction. In an open landscape, they may reach approximately 40 to 80 feet tall and 60 to 100 feet wide. However, in the forest, it stands more erect, growing to 100 feet tall.
This tree grows moderately fast in youth, and if properly located and maintained, may produce 2 to 2½ feet of growth per year. Trees grown outside the coastal region will grow more slowly. The growth rate also slows with age. As one of the longest-lived oaks, some live oaks may live 200 to 300 years.
The live oak is probably best known for its massive horizontal limbs that give older trees their majestic appearance. The trunk can grow to more than six feet in diameter. Live oak leaves remain on the tree through the winter, then yellow and drop as new leaves expand in the spring. However, trees growing further inland become semi-evergreen and lose some of their leaves during fall and winter. The waxy leaves are resistant to salt spray.
The small (1 inch) acorns, produced in clusters of one to five, are dark brown to black when ripe, and are a primary food for many wildlife species along the coast.
Live oak is susceptible to leaf blister, a fungal gall that disfigures leaves and may cause some leaf drop, but does no appreciable harm. Rake up and dispose of or burn dropped foliage to reduce the severity of this disease the following year. Several insect galls may become a minor problem, but control measures are generally not required for leaf insect galls. Oak wilt is a serious fungal disease that can kill infected oak trees within a year or two. This disease occurs in only six counties in South Carolina: Chesterfield, Kershaw, Lancaster, Lee, Darlington, and Barnwell. Fortunately, there have been no documented cases of oak wilt on live oak, probably because the vast majority of live oaks are in the coastal counties. For more information on problems of oak, refer to HGIC 2006, Oak Diseases & Insect Pests.
When grown in the South Carolina Piedmont, outside of their natural range, live oaks may be either injured or killed by cold temperatures. For this region, select cold-tolerant cultivars or seed-propagated live oaks with proven cold hardiness.
Note: Chemical control of diseases and insects on large trees is usually not feasible since adequate foliage coverage with a pesticide cannot be achieved.
Live oaks are reminiscent of the Old South, especially when planted along avenues or drives leading to old plantations. Although used extensively for street tree plantings, in time, the roots will lift sidewalks or streets if planted too close. Live oak does well as a lawn specimen when provided plenty of space to grow.
Although grown best in well-drained, sandy soils with plenty of moisture, it tolerates drier, more compacted soils. Once established, live oak is drought-resistant. It prefers full sun but tolerates more shade than other oaks because its leaves function throughout winter.
Pruning is only necessary to develop a strong branch structure early in the life of the tree. Train trees to grow a central leader by eliminating young multiple trunks and branches. Prune in mid-to-late summer to avoid oak wilt disease.
Cultivars & Varieties
Highrise® – This was the first patented cultivar of live oak. It was discovered growing as a seedling in Orangeburg, SC. It has a uniform, upright pyramidal growth habit with a mature height and spread of 30 to 40 feet by 12 to 18 feet, respectively.
Cathedral Oak™ – This cultivar has a pyramidal canopy when young that becomes broad to ovoid as it matures. It is expected to have a mature height and spread of 40 to 80 feet by 60 to 120 feet, respectively.
Millennium Oak® – This cultivar has the traditional, picturesque growth of live oak and has a predictable growth rate and habit. Expect a mature height of 50 to 75 feet and a spread of 60 to 100 feet.