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Saturday - July 18, 2009

From: Houston, TX
Region: Southwest
Topic: Septic Systems
Title: Will a 10-ft. yaupon damage my septic lines in Texas Hill Country?
Answered by: Barbara Medford


A 10 foot yaupon is growing in my Texas hill country septic field. The field pipe is 5 feet below the surface. Should I be concerned about the roots invading the pipes? What would be the best way to remove this tree?


We have had a number of questions about what to plant and what not to plant over a septic field. Woody plants, such as your Ilex vomitoria (yaupon), are definitely on the "what not" list. Here is an excerpt from one of our previous answers that addresses your question:

"You don't want any woody plants close to your lateral lines, as in trees and shrubs. They are the ones that send roots out far beyond their driplines, sneaking up on you. But you don't want to leave that area completely bare, because you know it wouldn't stay bare, it would get weedy and unless it was mowed, some of those "weeds" would grow up to be woody plants. We don't know how your lateral lines are situated, but you do need to be aware of them if you plant a tree in that area. If the area is too near the lateral lines, you may have to reconsider what you plant there." 

The best way to remove the tree is to dig it up, roots and all. With a tree that size, that probably is not practical. Second choice, get some wide-spectrum herbicide and some disposable sponge paintbrushes. Cut the tree trunk(s) off near the ground surface and, within five minutes, paint the cut surface with the herbicide. This must be done quickly so the herbicide can get down into the root system before the tree heals that cut surface over to protect itself. Then, keep after it-that tree is going to be struggling to survive, and the root system will probably put up some suckers, which represent small "branches" trying to grow leaves to produce food through photosynthesis to keep the roots alive. And it wouldn't do any harm to continue trying to get the roots out of the ground. Even if you don't get them all out, the more that are gotten out, the fewer there will be to continue to try to get into all that nice moisture in your septic field. 

The best replacement in the area over a septic field is native grasses. They have fibrous roots that will hold the soil, and help to crowd out woody plants, although you need to keep any eye out for those, too, and pull them out when you see them. We are going to suggest some grasses native to the Texas Hill Country that will be attractive, cover the bare soil, and hold that soil, protecting from erosion.

We don't know if you are dealing with an urban property or out in the country; whether you need lawn-type grass or just ground cover. You might read our How-To Article Native Lawns to get an idea of what the possibilities are.  Our favorite native lawn grass is Native Sun Turf, from Native American Seed, which is 34% Bouteloua gracilis (blue grama) and 66% Bouteloua dactyloides (buffalograss). However, the key word here is "sun," which you may not have, or not full sun, which we consider 6 or more hours of sun a day. We will go to Recommended Species in our database, click on Central Texas on the map and select "Grass" and "Part Shade." You can use the database in the same way, finding choices that suit you better.

Grasses for Septic Line Area in Central Texas

Andropogon gerardii (big bluestem) - perennial warm season grass, 4 to 8 ft. tall, sun or part shade

Bouteloua curtipendula (sideoats grama) - perennial warm season grass, sun or part shade

Schizachyrium scoparium (little bluestem) - 18 to 24 inches, sun or part shade

Chasmanthium latifolium (Inland sea oats) - 2 to 4 ft perennial, deciduous, part shade or shade

Ilex vomitoria

Bouteloua gracilis

Bouteloua dactyloides

Andropogon gerardii

Bouteloua curtipendula

Schizachyrium scoparium

Chasmanthium latifolium



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