Ask Mr. Smarty Plants

To quote from our webpage on Quercus stellata (post oak):

"Post oak is the most common oak throughout Texas. The typical places to see it are sites with sandy or gravelly soils. Its acorns are an important food source for deer, squirrels, wild turkeys and other wildlife. Larval host for several butterfly species. This plant is common in the central and southern forest regions, where it is a medium-sized tree. This is the ultimate drought resistant tree, but also grows in soggy, flatwoods soils. In dry portions of the western part of its range it is smaller. Its roots are extremely sensitive to disturbance. Susceptible to oak wilt. Not often used in landscape situations. Slow-growing and long-lived."

This oak is not often used in landscape situations because it is very hard to transplant, and therefore seldom available in commercial plant nurseries. The oaks you have probably grew where the acorns dropped, rather than having been selected for the site. If you had been selecting trees, you might have avoided this one because of its susceptibility to oak wilt and also because of its sensitivity to root disturbance. As you can see from this Botanical Research Institute of Texas Vegetation Map of Texas, Travis County is right on the edge of the southern end of the Post Oak Savannah, so it belongs here, and can get by on the typical Austin soil. 

Grasses to go beneath the Post Oaks are going to be a little more problematical. We assume you are not asking for a turf-type grass, as most of them require sun, and won't like those fibrous roots right under them. Furthermore, most of the popular lawn grasses are non-native to North America, and would not be recommended by the Lady Bird Johnson Wildflower Center. Nor will the tree like much disturbance in planting grasses.  We're going to suggest several somewhat ornamental grasses, all native to this area. Because they are native they are going to require less water, fertilizer and maintenance. Taking care to disturb the tree roots as little as possible, they can be planted as clumps, in the Fall or Spring, and allowed to spread naturally and co-exist with the oaks. The grasses we have selected are all somewhat shade tolerant, and will hold their place and be attractive year-round.

When you have made some selections, you can go to our Native Plant Suppliers section, type your town and state into the "Enter Search Location" box, and you will get a list of suppliers of native plants and seeds, and names of landscape consultants experienced in working with native plants. 

Bouteloua curtipendula (sideoats grama)

Carex texensis (Texas sedge)

Chasmanthium latifolium (Inland sea oats)

Eragrostis intermedia (plains lovegrass)

Nassella tenuissima (finestem needlegrass)

Nolina texana (Texas sacahuista)

Quercus stellata

Quercus stellata

Bouteloua curtipendula

Carex texensis

Chasmanthium latifolium

Eragrostis intermedia

Nassella tenuissima

Nolina texana