News Release Distributed 02/18/11

By LSU AgCenter Horticulturists Dan Gill, Kyle Huffstickler and Allen Owings

Southern live oaks, known by the scientific name Quercus virginiana, are one of the most popular trees found in Louisiana landscapes. They certainly are considered to be a signature tree in many public places across the state and are widely used in home landscapes.

They are very familiar to visitors on the LSU campus in Baton Rouge. And live oaks make the news when development threatens individual plants. You can register and name 100-year-old live oaks with the Live Oak Society operated by the Louisiana Garden Club Federation. Live oaks certainly are one of Louisiana’s most sustainable trees.

The winter months are a great time to provide care and maintenance to your live oak trees. From selecting trees at the garden center to planting, pruning and fertilization, this is the time of year for live oak maintenance.

Live oaks are grown at many wholesale nurseries in Louisiana and are one of the most sold trees at garden centers.

If you intend to plant a live oak, select a tree with a well-developed central leader system. And be sure the tree was properly pruned at the nursery. Proper pruning at a young age is important for live oaks long term. Most home gardeners should plant trees growing in 3- to 15-gallon containers, although you can purchase live oaks that are much larger. It is hard, however, for an average homeowner to handle planting trees larger than those growing in a 15-gallon container.

When planting, be sure to follow LSU AgCenter tree-planting recommendations:

– Make the planting hole the same depth and two to three times as wide as the container in which the tree has been growing.

– Make the sides of the planting hole rough, not smooth.

– Put into the planting hole the same soil that came out of it.

– Do not amend this backfill soil with compost, pine bark or similar materials.

– Water the tree during the planting process to eliminate dry pockets that will desiccate the new growing roots.

– Mulch trees after planting.

Be sure to give your new live oak tree adequate room. Most of the time, live oaks are now planted on 30-foot-by-30-foot spacings. This is, however, way too close. You also see live oaks planted on 60-foot-by-60-foot spacings. This is OK. But ideally, live oaks need to be planted on 90-foot centers. We all see live oaks in front yards that have basically no room for a tree this large. Also, live oaks routinely are planted between streets and sidewalks. Once again, this is the wrong tree in the wrong place. Be sure to plant live oaks where they have room to grow and do what they want to do.

Fertilization of live oaks is not recommended the first year after planting. You can start a fertilization program thereafter.

During the first year, growth emphasis on the tree should be directed to the root system. Nitrogen fertilizer applications during this time favor shoot growth at the expense of root growth.

Mature live oaks may benefit from fertilization, or they may not need fertilization at all. The tree needs to be examined for new growth. If new growth, as measured by shoot elongation, is significant, fertilization is not needed. If not much new growth or no new growth is apparent, fertilization or other cultural practices may be needed. A licensed tree-care professional should examine your mature live oak trees in most of these situations to determine a course of action.

Live oaks originating from seed sources in Louisiana will grow best in Louisiana. In other words, do not expect acorns obtained from a tree in Texas to produce a tree in Louisiana that would grow as well as it would grow in Texas. We are fortunate to have the Orange Island live oak, a sexually produced variety, propagated here in Louisiana by Live Oak Gardens in New Iberia. It is a very vigorous-growing live oak and is better than other varieties.

Wholesale growers also now have access to the Cathedral and Highrise varieties of live oak. These are asexually propagated from stem cuttings and produce trees that are similar in growth habit, size, etc., so they have a uniform look in a landscape planting. These are not being grown in large numbers in Louisiana, and their availability is limited for home gardeners.

Live oaks are one of our most important trees. Provide proper care to these great trees.

Visit LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge, across the street from the LSU baseball stadium. For more information, go to www.lsuagcenter.com/lahouse and www.lsuagcenter.com/lyn.