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Express-News Weekly Column Saturday, November 4, 2000 Submitted by Calvin Finch, Ph.D.,
Director of Conservation, SAWS, and Horticulturist

Fall color is not one of our claims to fame in the San Antonio area. We can visit Lost Maples State Park (located 5 miles north of Vanderpool, TX, on Ranch Road 187 or visit the web site at http://www.tpwd.state.tx.us/park/lostmap/lostmap.htm and see good fall color from the big tooth maples most years, but the show at the park is an exception.

If you select well, however, you can have a landscape that offers some decent autumn color. Texas red oak (up to 70 feet tall, usually 45 to 50 feet) is one of the best shade trees for South Texas and it can also offer red leaf color before the leaves fall. Now through early spring is the best time to plant shade trees. The acorns that are planted for the red oaks in the nursery are selected from mother trees with good color, but there is considerable variation. If you see a Texas red oak in the nursery that shows good color this autumn, pick that one.

Red oaks do have some susceptibility to oak wilt, so you may want to select another species if your neighborhood is dominated by live and red oaks. Even in the worst case scenarios, however, only 5 percent of the red oaks get the disease. Paint all fresh wounds in the neighborhood and the oaks should be safe.

Texas red oak is a good xeriscape tree; it can tolerate recurring periods of drought. Like most drought tolerant plants, however, it is sensitive to over-watering when it is newly planted. To avoid having the roots drowned the first growing season, dig the planting hole only as deep as the tree in the container and 2 or 3 times as wide. Do not add organic material or sand to the soil that is put back in the hole. Fill the planting hole with the native soil so that water enters the hole at nearly the same level that it can drain out. The rule is that organic material is wonderful when spread and incorporated over a large planting area, but can be deadly in a planting hole in our poorly drained clay soils.

Apply 3 to 4 inches of mulch over the roots of your newly planted trees and water when the soil dries to 1 inch under the mulch. If you allow the lawn grass to grow right up to the trunk of the newly planted tree, the growth rate can be reduced by 40 percent.

Texas red oak is a high-quality, fast-growing shade tree that provides good fall color. Chinese tallow is usually short-lived and has some characteristics that merit its description as a weed tree, but it can provide some spectacular autumn leaf color. Chinese tallow is less red and more purple-bronze than red oak. The white seeds are also attractive and provide food for birds in late winter and early spring. The tree can reach 40 or 50 feet on good soils, but on typical South Texas soils reach only 30 to 35 feet before cold weather, wind, borers, and other ailments end its life.

Most nurseries do not carry tallow to sell; but, if you have the species in your neighborhood, you can easily find a seedling to transplant. They grow very fast, so pick a small seedling or just bury some seed in a container or corner of the yard.

Sometimes we forget that some selections of crepe myrtle also have good fall color. Natchez (white flowers) at 20 to 30 feet, Tuscarora (pink flowers) at 20 to 25 feet, and Basham's Party Pink at over 25 feet, have among the best fall color. All crepe myrtles have good summer bloom when planted in full sun and may also have attractive colorful bark that is showy in the winter landscape.

Crepe myrtles are good xeriscape plants for maximum bloom. They do require one deep watering per month during the summer.

Big tooth maple, the star of the Lost Maples State Park autumn leaf color show, unfortunately, is not easy to grow in the flatlands and rarely makes a good color show. Our poorly drained soils and high night temperatures seem to reduce its enthusiasm for growth and color in the San Antonio area.

For a shrub, check the standard nandinas. When grown in the sun, the drought resistant shrub can have spectacular leaf color all winter.