2020 Annual UGA Extension Gwinnett Plant Sale

UGA Extension Gwinnett is offering many fine plants at affordable prices at the 2020 Annual UGA Extension Gwinnett Plant Sale. Use the above form.

Live Oaks: State Tree of Georgia

   If you have ever been to Savannah or Charleston, one thing you are sure to have noticed is the large oak trees lining the streets.  These trees are called live oaks (Quercus virginiana) and are the state tree of Georgia. Live oaks are native to the sandy soils near the coast but can also grow in the moist, fertile soils of woodland areas, along stream banks, and in a variety of other site conditions.
     Live oaks are magnificent trees for street plantings and large estates, but they are not well suited for small properties. The trees have broad spreading horizontal limbs with trunks up to six feet in diameter. They have the potential to grow 40 to 80 feet in height, 60 to 100 feet in width, and can live for centuries. During the earlier years of the tree’s life, it can grow two to three feet a year, and up to one inch in width per year. They should be planted in large open areas, such as parks and large yards, to accommodate their wide-spreading limbs. The tree is evergreen in warmer areas, but it drops its leaves in colder climates. Its wood is one of the heaviest of the native hardwoods and can weigh as much as 55 pounds per cubic foot. In the days of wooden ships, the wood from live oak was the preferred source for the framework for them. Live oak trees provided much of the lumber used in the construction of the U.S.S. Constitution—“Old Ironsides.” 
     Birds, squirrels, chipmunks, and deer love the sweet-tasting acorns of the live oak; a mature tree can produce thousands of them. The waxy leaves increase their tolerance to the saltwater spray, which gives them the ability to thrive along saltwater marshes and beaches. They prefer the milder climates of the coastal plain, but will also grow in North Georgia. However, the live oaks will not grow to the size they can become in the coastal plains due to the colder winters and clay soils in the northern part of the state.
     Once established, they are remarkably hardy and can survive in almost any location. Although live oaks prefer sandy, loamy soils, but can tolerate more compacted clay soils. Once established, they are very tolerant of drought conditions. The trees prefer to be in full sun but can tolerate some shade. It can survive construction activities and root damage better than most trees. The deep roots of the tree and its durable wood increase its resistance to toppling over in the high wind. Live oaks generally have minimal pest problems.
     If you decide to plant a live oak, remember it will grow huge, so in small yards, choose another tree that will better fit your needs.  If you have the space to grow these trees, then in time, you will have a beautiful gigantic shade tree.

Live oak tree growing behind the Dekalb County Extension Office in Decatur, GA. 

Most ones do not reach this size in North Georgia. Photograph by Timothy Daly

Mulch has a Multitude of Benefits

Pine straw is one of the most commonly used mulch.
Photograph by Timothy Daly

    The application of mulch is a critical cultural practice in the home landscape. The use of mulch helps the soil to retain moisture, improves the appearance of the landscape, and has numerous other benefits. Using mulch is an essential component of ‘xeriscaping,’ which is the implementation of several tactics that reduce the need for the application of water in the landscape.

      Mulch reduces the evaporation of soil moisture, thus making more of it available to plants. It also prevents the formation of crusty soil, which improves the infiltration and movement of water in the soil. Mulch insulates the soil and helps prevent drastic fluctuations in soil temperature, thus keeping the roots cooler in summer and warmer in winter. It also adds organic matter to the soil and reduces soil erosion.

     Covering the bare soil with mulch reduces the germination of weeds that compete with the desired plants for moisture and nutrients. It also acts as a barrier between the plants and the soil, reducing the likelihood of soil-borne plant diseases. Mulched areas also act as a buffer zone between the turfgrass areas and ornamentals, which prevents damage to them from lawnmowers and other landscaping equipment.

      Fine texture organic mulches, such as pine straw, pine bark mini-nuggets, and shredded hardwood mulch, are preferable to the coarse-textured mulches like large pine bark nuggets. The fine-textured mulches do a better job of holding moisture in the soil. Avoid using lava rock, marble, or gravel as a mulch. These materials absorb the intense heat from the sun, which can be harmful to the plants.

     Apply at least three to four inches of fresh pine straw around your shrubs or roughly three inches of pine bark or shredded hardwood mulch. Around trees and shrubs, always pull back some of the mulch two to three inches away from the main trunk.  Excessive mulch may cause the roots to grow mostly in the shallow upper layers of the soil due to decreased ability to absorb oxygen and water, as well as increase the risks of root diseases.

    The plastic film should never be used as a mulching material. It can hold too much water leading to root rot. Landscape fabrics are preferred since they are porous and allow for the penetration of water and air. However, they are challenging to install, they will not prevent the germination of certain weeds like nutsedge, and they must be covered with organic mulch.  Removing the old mulch every year and replacing it with new mulch is not necessary since the organic mulch rots due to the activity of the microbes in the soil.  Fresh mulch can be applied directly to the top of the already-existing, partially rotted mulch until it is three to four inches high. For example, if the existing layer of mulch is two inches thick, then add only a thin layer of mulch, roughly one inch.

    In conclusion, applying the proper mulch to the home landscape creates a more pleasing appearance and also helps promote good plant health in a variety of ways.

Avoid using marble, lava rock or gravel as a mulch. It absorbs heat
and can cause the plants.to suffer heat stress and to dry out.
Photograph by Timothy Daly

Use Alternative Plants to the Troublesome Leyland Cypress

Japanese cryptomerias are an excellent alternative to Leyland cypress trees.
They have few issues with pests and will thrive with minimal
maintenance if planted in the proper site.  Photograph by Timothy Daly,
 UGA Extension Gwinnett

     Throughout our area, Leyland cypress trees are everywhere. Homeowners plant them to screen out unwanted views or for privacy. These trees have the advantage of being attractive and growing rather rapidly. They have the potential to grow up to 60 feet tall and have a 15 to 20-foot spread.  Extension office receives many calls from homeowners with issues about their Leyland cypress trees declining and dying.  Frequently, these trees are planted too close together which reduces the sunlight the plants receive, thus causing them to decline. Leyland cypress trees also tend to be vulnerable to premature death and pest problems such as fungal canker diseases and root rot. The only solution in most cases is to remove the tree. However, several alternative plants can be used that are less problematic. 

    If you desire a conifer plant that resembles the Leyland cypress, consider planting arborvitaes and Japanese cryptomerias. Several varieties of arborvitaes are available, but one of the hardiest is ‘Green Giant’. It can grow to 30 feet in height and has a width of 15 to 20 feet. The leaves are light green and needle-like with the younger ones being feathery and the older ones more scale-like. It requires moist, fertile and well-drained soil, and full sun. Japanese cryptomerias have a pyramidal shape and become more narrow shaped and oval as they mature. They can grow up to 50 feet high and over 20 wide, but their rate of growth is slow. The foliage turns bronze in the winter. They require full sun and loose soil that has proper drainage. And, while they can tolerate dry spells, they do need occasional watering during dry spells.

    Many broadleaf evergreens have similar qualities to the Leyland cypress. The Southern magnolia creates a dense screen. The ‘Little Gem’ variety has a short, compact, upright growth. The tree is excellent for sites that need a smaller screen. One drawback is that the tree continually sheds leaves throughout the season, so it should be planted at sites where the falling leaves will not be troublesome. For wet sites, the sweetbay magnolia is a good choice. It has dense, evergreen foliage. The upper part of the leaf is green, and the underside is a green to white color.

    Several species of hollies have many of the attributes of Leyland cypress trees. Foster hollies and Savannah hollies both have dense foliage, a pyramidal growth habit, and can reach a height of 20 feet or more. The ‘Nellie R. Stevens’ holly has a more compact growth habit but still has an excellent ability for screening.

    Some smaller growing plants can provide excellent screens as well. Wax myrtles, which are native to South Georgia, thrive in hot, dry conditions and poor soil, but they need full sun. The leaves and stems are fragrant. Other choices include cleyera, loropetalums, camellias, and several species of viburnums.

    Though Leyland cypress trees are popular and attractive in the landscape, using a different variety of plant with minimal difficulties will provide an alternative to the Leyland cypress. 

Several hollies, including the Nellie R. Stevens holly, in picture above, can functions as
screens and are better suited to the home landscape than Leyland Cypress. Photograph by
Timothy Daly, UGA Extension Gwinnett

Leyland Cypress Trees Require Sufficient Space

Leyland cypress trees suffer from fungal diseases and other maladies,
especially when planted too close together. Photograph by
Timothy Daly, UGA Extension Gwinnett.

  One of the most widely planted trees in landscapes across Georgia is the Leyland cypress. It has many appealing qualities, such as its pyramidal shape, attractive dark green foliage, and a rapid growth rate.   The tree can be used as a screen to block unwanted views and enhance privacy. Despite its virtues, the plant frequently performs poorly in the landscape as a result of improper planting practices.

    Leyland cypress trees can grow 50 to 70 feet high with a spread of 15 to 20 feet.  However, they are usually planted too close together.  The trees should be at least 10 feet apart, preferably 12 to 15 feet apart, and a minimum of 15 feet away from structures. Planting at this distance doesn’t make them a useful screen for some time. However, they can grow four feet per year in height and two to three feet in width. In three to five years, they will be effective screens. If waiting a few years is not right for you, the trees can always be planted closer together with the understanding that every other one will have to be removed in time.  You can also plant other evergreen plants such as arborvitaes, Japanese cryptomerias, wax myrtles, or certain types of hollies as an alternative to the Leyland cypress. They form effective and attractive screens also.     

    Leyland cypress trees need to be planted in locations that receive full sun. The shade will reduce their vigor and cause the leaves and branches to thin out. The trees require fertile, well-drained soil. One of the most critical factors in the growth of Leyland cypress is making sure they are adequately watered. Inadequate amounts and also excessive amounts of water will cause Leyland cypress trees to suffer and decline.

     Leyland cypress trees can become infected with a couple of stem canker diseases caused by a fungus. The primary symptom is the foliage on the top of the lateral branches turning yellow or brown.  The disease can potentially disfigure or kill the trees. Prolonged dry conditions and being planted too close to each other have contributed to the development of these diseases. Since there are no effective chemicals for control, the best way to treat an infected tree is to prune out the dead branches. Cut below where the canker has formed on the branch and sterilize the pruning tool in alcohol or bleach before making the next cut to prevent the spread of the disease. If trees that have been extensively damaged or if the trunk itself is infected, they should be cut down. Also, during dry spells, make sure the trees receive the proper amount of water, which will reduce the development of the disease.

        Leyland cypress trees can be a great addition to the landscape if properly planted and maintained. However, this tree is rapidly becoming one of the most troublesome trees in the landscape. Due to improper planting and overuse, Leyland cypress may go the way of plants such as the Red Tip Photinia. This small tree was planted extensively in the 1970s and 80s as a hedge, but eventually, a fungal leaf spot disease caused many of them to die out.