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Monday - January 21, 2008

From: Austin, TX
Region: Southwest
Topic: Privacy Screening
Title: Trees to replace Ligustrums, and evergreen vines for privacy screen
Answered by: Nan Hampton

QUESTION:

We had 3 ligustrum trees growing along a creek bank in our back yard and under the City of Austin power lines. Our backyard is on a terrace about 7 feet above the creek's flood plain. The Ligustrums were down below at the creek level. Following the advice of my arborist we cut down the ligustrums and planted some replacement trees provided by the city. Now we totally regret cutting down the ligustrums. The new trees are very small (3 5-gallon Yaupon Holly and 3 1-gallon evergreen sumacs and there really isn't enough space to plant trees with larger root balls. The area is also subject to flooding and erosion during severe storms. The new trees are planted 7 feet below the back yard. The main problem is our deck, which used to be nicely shaded and screened by the Ligustrums. Now it has little potential shade other than a young northward facing Cedar Elm. The sumacs will eventually grow up to about the level of our deck railing but I'm not expecting much higher, and even though I like Yaupon Hollies very much, they grow so slowly! I am thinking of planting a tree on the upper terrace that can eventually provide a shade canopy for the deck. Unfortunately, even the upper terrace is close to the power lines. So far my choice is a Mexican Plum. Will it provide much shade? For other privacy I am looking for some evergreen vines to grow on trellis panels. My arborist tells me I did the best thing getting rid of the invasive non-native Ligustrums and putting trees for the future, but right now we feel totally exposed (and I think my neighbor across the creek hates me!).

ANSWER:

Mr. Smarty Plants stands solidly with your arborist and applauds you enthusiastically for getting rid of those nasty, invasive Ligustrums (Ligustrum japonicum, L. lucidum, L. quihoui, L. sinense and/or L. vulgare). This particular Mr. SP (yes, there's more than one of us) understands well your problem, however, having last year cut down a stand of Ligustrum left by the previous property owner. They do provide shade and privacy but at the expense of beautiful native trees that can do the job as well or better. You will need a little patience until your natives grow and fill in the spaces to provide your privacy. Believe me, you'll be glad those Ligustrums are gone!

There is an online resource, Texas Tree Planting Guide, from the Texas Forest Service and Texas A&M University that can help you choose the right tree for your space. In this database you can select the characteristics you are looking for in a native tree that will grow in Travis County, Texas. Prunus mexicana (Mexican plum) is certainly one of their choices for a small tree native to Texas. It is an excellent choice for several reasons—it would provide a good widespreading shade, it has beautiful flowers in the spring and fruit for you and your urban wildlife in the fall. Its growth rate is moderate. Here are other suggested choices from the Texas Tree Planting Guide, with a few added comments:

Fast-growing:

Cercis canadensis var. texensis (Texas redbud) has beautiful flowers in the spring and yellow fall foliage.

Chilopsis linearis (desert willow) also has beautiful flowers.

Moderate growth rate:

Pistacia mexicana (American pistachio) is semi-evergreen and can be pruned to create a shrub or a tree.

Slow-growing:

Cotinus obovatus (American smoketree) has beautiful fall colors. With ample watering it will grow faster but care must be taken not to overdo the watering since the rapid growth can make the wood weak.

Condalia hookeri (Brazilian bluewood) is evergreen and has thorns.

Viburnum rufidulum (rusty blackhaw) has showy flowers and colorful fall foliage.

Sophora secundiflora (Texas mountain-laurel) is evergreen and has beautiful, fragrant spring flowers.

Diospyros texana (Texas persimmon) with pruning will form a single- or multi-trunked tree.

There are lots of beautiful vines that are native to our area, but unfortunately not many are evergreen. Here is a list of evergreen, or almost evergreen vines:

Gelsemium sempervirens (evening trumpetflower). This is the only true evergreen vine that is native to Texas.

The following three are listed as semi-evergreen: Bignonia capreolata (crossvine), Cocculus carolinus (Carolina coralbead), and Lonicera sempervirens (trumpet honeysuckle).