Ask Mr. Smarty Plants

Grasses are ideal for erosion control because of their extensive fibrous root system that tend to hold the soil in place.   Here are some suggestions for grasses:

Height—about 3 feet or less

Bouteloua curtipendula (Sideoats grama)

Bothriochloa laguroides ssp. torreyana (Silver beard grass)

Koeleria macrantha (Prairie junegrass)

Muhlenbergia capillaris (Gulf muhly)

Pascopyrum smithii (Western wheatgrass)

Schizachyrium scoparium (Little bluestem)

Height—3 to 8 feet

Panicum virgatum (Switchgrass)

 Andropogon gerardii (Big bluestem)

Sorghastrum nutans (Indiangrass)

All of the above grasses will grow from seeds and, although earlier in the year would have been a better time to plant, you should be able to get them to sprout and grow now—providing, of course, that you give them plenty of water.  Native American Seeds has an article, Planting Tips for Native Grasses, that has useful information for getting your grasses established. You don't say how steep the slope is that you are trying to stabilize, but if it is very steep you might want to consider using some sort of erosion control mat or blanket called rolled erosion control products (RECPs).  They help stabilize the area until the grass can take over that function.   You sow the seeds under the blanket and they grow up through it.   Sowing the seeds under the blanket also keeps them from washing away in the rain or during the irrigation of the area.  Many of them are made of biodegradable material that eventually decomposes.  Many nurseries carry some form of these.

Here are some other plants to intersperse in the grasses that can help stabilize the slope:

Conoclinium coelestinum (Blue mistflower)

Monarda citriodora (Lemon beebalm)

Oenothera speciosa (Pink evening primrose)

Phlox pilosa (Downy phlox)

Artemisia ludoviciana (Louisiana artemisia)

You can search in our National Suppliers Directory for seed companies that specialize in native plants in your area.