Our Live Oaks around homes and cities require certain conditions to survive and prosper. The homeowner should be concerned regarding the landscape activities of planting near oaks, irrigation and feeding, pruning, disease and insect infestations. Most native oaks in Texas evolved and prospered in an environment typified by a cool, moist winters and hot, dry summers. Under natural conditions, surface soils are wet during the cooler months and become dry by summer. Natural vegetation growing around and beneath oaks are usually dormant during the winter and flourishes during spring and by late summer, and into early fall creating the well-known golden-brown landscape, of Texas' valleys and foothills. Native live oaks, however, remain green because their thick, leathery leaves and other adaptive features reduce their growth rate and water use. The homeowners should attempt to approximate the natural environment in which these magnificent trees are in their natural setting. When cared for properly, live oak has a moderately rapid to slow rate of growth. 

SOUTHERN LIVE OAK (Quercus virginiana) - A large, sprawling, picturesque tree and it is highly desirable as a landscape tree. The Live Oak is one of the broadest spreading of the Oaks, providing large areas of deep, inviting shade. Reaching 40 to 60 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-scaled landscape. Give it  plenty of room since the trunk can grow to more than six feet in diameter. An amazingly durable American native, it can measure its life in centuries if properly located and cared for in the landscape.

In Texas, live oaks learned ten thousand years ago that Texas soils and environmental conditions are not conducive for propagation from the acorns. They depend on animals and birds to transplant acorns away from the parent tree for the sake of forest diversity. Live oaks are very bad parents and do not want competition from their siblings, so they predispose a fungus to kill the germination of the acorns that remain under the tree. Live oaks propagate in a very unusual manner, they put out ramets (sending-up root sprouts) from the mature roots, or otherwise a bud that grows off the root. This method ensures 100% survival as the new shoots have a fully mature root system for support. They actually clone themselves, a Mott or grove of a few or up to hundreds of trees are really all the same tree and can cover large acreage areas.

Planting Near Oaks

Only drought-tolerant plants that require no summer water should be planted around old established oaks and they should be planted 6' from the base of the tree. DO NOT plant exotic grasses, ivy, or other vegetation requiring summer irrigation near them.

Irrigating and Fertilizing

Native live oaks usually do not require measurable amounts of irrigation, however they usually thrive in our suburban landscapes if properly cared for.  Healthy live oaks are even able to survive the excessively dry summers.  Frequent, shallow watering not only encourages crown and root rot, it results in ineffective shallow roots near the surface. Under no circumstances should the ground near the base of  a live oak be allowed to become moist during warm periods. Deep watering  at the critical root zone, which the drip edge and outward is far more effective and responsible.

Mature trees usually need little supplemental  nutrient replacement. Fertilization should be done only to maintain vigor and if growth is poor. Lighter and frequent applications will produce better results and allow the trees to grow at a more natural and slow rate.  Heavy fertilization will create rapid, lush growth, which is a loud dinner bell for insects and other disease. Excessive fertilization causes the tree to divert its defense energy against disease and insects, to growth.  Trees that have recently undergone severe pruning or root damage should not be fertilized for at least six months. 

Diseases and Insects  

Native Texas live oaks are relatively tolerant of most diseases. In early spring, timed at leaf out, live oaks can be attacked by a barrage of leaf eating insects. The cankerworm and leaf rollers are the most common predators and can literally defoliate a tree over night. However, using a safe foliar application of Bt (a Bio-pesticide) can keep them under control.  It is most unfortunate, they are subject to OAK WILT which has devastated many trees in parts of central Texas. Studies have shown that they can be replanted successfully in old and developing oak wilt centers. Precautions must be taken to prevent wounding. Wounds attract sap feeding beetles that carry the oak wilt fungus spores. If the tree is wounded or it has to be pruned, immediately paint with a light application of spray paint. The light dressing application of paint forms an insect barrier and allows the wound wood to properly cure.

 Soil Compaction and Trenching

The root zone or rhizophere under a tree is like a fresh piece of baked bread, it contains all the caterpillars, gases (oxygen, hydrogen and nitrogen) moisture, microbial life and nutrients. When compacted or squeezed flat like a tortilla, all the gases, moisture and nutrients are no longer available. This soil compaction under a tree can cause serious root damage and crown loss over extended time. Contractors should take all necessary precautions to protect trees during construction and many trees are two and three hundred years old and can never be replaced.  In all my years, I have never been able to place a significant value on a near 400 year old live oak tree. This is priceless!  An eight year old boy summed it all up... " That is a non-renewable resourse of energy" !!!!!     That changed my attitude!

Trenching near the critical root zone is often overlooked as a cause of tree death. Trenching usually occurs when underground utilities are installed. Digging a trench within the root zone can severe a significant portion of a tree's roots and cause damage to the tree. Ninety five percent of all tree roots are within the top 12 to 16 inches of the surface soils and can extend three times beyond the drip edge.  

Landscape Paving, and Landscape Fill Around Oak Trees