Mr. Smarty Plants can't help you with the retaining wall part, but he can suggest some plants that you can use to help stabilize the slope. We usually recommend grasses for this because their fibrous root system helps to hold the soil particle and prevent erosion. When you hear "grasses" you may think about the turf grasses that require mowing to appear attractive. The grasses we are suggesting are sometimes called ornamental grasses or bunch grasses that require no mowing. Planting a combination of grasses , sedges, and small flowering plants may provide the stabilization that your slope needs. You may want to consult a structural engineer or a landscape architect to deal with the issues concerning the retaining wall.
Lets start by going to our Native Plant Database and scrolling down to the Combination Search box and make these selections; select North Carolina under State, Grass/grass-like under Habit, Perennial under Duration, Sun under Light Requirement, and Moist under Soli Moisture. Click the "Submit Combination Search" button and you will get a list of 45 native plants in North Carolina that match these characteristics. Clicking on the name of each plant will bring up its NPIN page that contains a description of the plant, its habitat and growing conditions along with images.
For the flowering plants we'll try another approach. Let's go to the RECOMMENDED SPECIES page and select North Carolina on the map. This will give you a list of 135 commercially available native plant species suitable for planned landscapes in North Carolina. Go to the Narrow Your Search box on the right side of the page and follow the procedure as before; selecting Herb under Habit instead of Grass/grass-like. Clicking the Narrow your Search button will trim your list to 18. You can alter either list by going back and changing your choices in the categories.
Here is a short list of grasses and sedges, as well as flowering herbs that you might consider for your hillside.
Our Suppliers Directory can help you locate nurseries close to you that sell the plants that you select.
Grasses and sedges