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Sunday - May 09, 2010

From: Dripping Springs, TX
Region: Southwest
Topic: Compost and Mulch, Seeds and Seeding, Erosion Control, Grasses or Grass-like
Title: Severely cutback sloping soil in Dripping Springs TX
Answered by: Barbara Medford

QUESTION:

We have 5.5 acres off Henly Loop just north of Hwy 290 about 10 miles west of Dripping Springs, TX. The former property owners carved out soil from a sloping area to get soil for the driveway. Doing so formed a large hole with 3 steeply sloping sides on all three sides next to the driveway. The soil appears to be a caliche mix (calcareous?). Oak trees, juniper and grasses surround the area along the hillside. However, nothing is growing on the sides to stop the erosion and part of one side area has started to cave in a little. What native plants or vines could we plant that could take hold and stop the erosion and restore some beauty to this scarred area? I have photos to attach but this box doesn't allow me to do so.

ANSWER:

If nothing, that is, not even weeds, which are usually native grasses, is growing from that slope, no plants suggest themselves to us that would solve the problem. If it is as serious as we understand from your description, we are surprised that it passed building inspectors, either when it was built or when it was sold to you.

We do urge you to get professional help from someone who understands the composition of your soils, and the degree of slope involved. We are gardeners, not civil engineers, so we can't determine if some grading to level out the degree of slope, and moving some excess soil away, or construction of retaining walls to hold those cut-away sides would be the most efficient. Once that problem has been resolved, and you have a manageable grade, we can go on to recommend plants for the area. If you would really like to send photos of your problem area, you can go to the Plant Identification section of Ask Mr. Smarty Plants, follow the instructions and submit the photo. It will not come to this particular member of the Mr. Smarty Plants team, and we will have already answered your question, but if you wish to do this, reference question No. 5557.

Extracted from a previous answer:

 

We recommend grasses for controlling erosion because of their extensive fibrous root systems that serve to hold the soil in place.  However, seeding grass is not the whole process.  The seeds need moisture to germinate.  If the moisture comes in the form of rain, it is likely to wash the seeds down the bank  before they have a chance to germinate and take root.  There are two possible solutions—an erosion control blanket or pneumatic compost/seed application.  The erosion-control fabric works by slowing the runoff water and allowing sediments to fall out rather than be washed away. Seeds are sown under the erosion-control material and grow up through the matting when they germinate. You can also insert plants into the soil by cutting through the matting. The roots of the plants that are growing through the erosion-control material anchor the soil to stop the erosion. If you use erosion-control blankets made of biodegrable material, they will eventually disappear leaving the plants to control the problem.  Many nurseries carry this erosion control fabric. 

The compost/seed application may be a bit more complicated and expensive than you had in mind since it does require a pneumatic blower, or some mechanical means, to spread the compost/seed mix. The US Composting Council offers information about suppliers of compost and compost technology, but I don't really know if this could be a do-it-yourself project.  You might check with a landscaping or environmental consulting company in your area who might have the machinery to do this to learn about the feasability and expense of applying the compost/seed mixture this way. You can find the names of Landscape Professionals and Environmental Consultants in your area that specialize in native plants by searching in our National Suppliers Directory.

We will go to our Native Plant Database and find grasses native to Central Texas that should help with your erosion. These are not lawn-type mowable grasses, but more decorative prairie grasses that, being native to this area, will be able to cope with soil and climatic conditions. Follow each plant link to the page on the individual plant for information on expected size and sun requirements. If your area has full sun (6 hours or more of sun a day), see this How-To Article Native Lawns: Multi-Species. We have listed 5 grasses that need sun, 6 hours or more of sun a day, 1 that grows in part shade, 2 to 6 hours of sun, and the others in sun, part shade or shade, less than 2 hours of sun a day. Follow each plant link to read more about the grasses to see which ones might work for you, once you get the slope in a condition to hold the seeds long enough to sprout roots.

While you could probably plant some vines at the top or the bottom of the slope, they will not help to hold the slope. Perhaps once the slope is stabilized, some vines could be used for decoration, but they are generally not a very good ground cover. 

Grasses and grass-like native plants for Central Texas suitable for erosion control:

Bouteloua dactyloides (buffalograss) - full sun

Bouteloua gracilis (blue grama) - full sun

Dasylirion texanum (Texas sotol) - full sun

Hilaria belangeri var. belangeri (curly-mesquite) - full sun

Muhlenbergia lindheimeri (Lindheimer's muhly) - full sun

Nolina texana (Texas sacahuista) - part shade

Schizachyrium scoparium (little bluestem) - sun or part shade

Sorghastrum nutans (Indiangrass) - sun, part shade or shade

From our Native Plant Image Gallery:

 


Bouteloua dactyloides

Bouteloua gracilis

Dasylirion texanum

Hilaria belangeri var. belangeri

Muhlenbergia lindheimeri

Nolina texana

Schizachyrium scoparium

Sorghastrum nutans

 

 

 

 

 

 

 

 

 

 

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