Ask Mr. Smarty Plants

I will suggest some plants that could help, but you may need to use additional measures to keep your streambank from eroding.  There are various biotechnical methods to stabilize streambanks and you can read about them in this excellent article from the USDA National Agroforestry Center, Biotechnical Streambank Protection: The use of plants to stabilize streambanks (Agroforestry Note #23, March 2002).  The article describes various streambank erosion problems and suggested solutions.  For slopes that are normally above the creek level grasses are very effective.  They have fibrous roots systems that are very good at holding the soil in place.  If you are experiencing a significant amount of runoff down the slope, you might want to consider laying down erosion control blankets (available at most plant nurseries) before spreading grass seeds.  Nearer to stream level you will want to have plants such as willows that can tolerate growing in very wet soils or even immerged in the water for periods of time. 

Here are some suggestions for grasses that do well in moist areas that you could plant on the slope above the stream.  Some of these will also grow near the stream edge.  There are suggestions for woody plants that will grow well closer to the creek edge.  Since I don't know the situation at your site for available sunlight and type of soil, you will need to check carefully the GROWING CONDITIONS on each of the species pages to be certain that they are compatible with your site.

Andropogon glomeratus (Bushy bluestem) grows well in wet areas and prefers full sun.

Andropogon virginicus (Broomsedge bluestem) is recommended for erosion control and grows in part shade.

Carex blanda (Eastern woodland sedge) grows in moist soils in sun, part shade or shade.

Carex cherokeensis (Cherokee sedge) grows in moist soils in part shade.

Chasmanthium latifolium (Inland sea oats) prefers shade or part shade and moist soils.

Cladium mariscus ssp. jamaicense (Jamaica swamp sawgrass) grows at the edges of streams in sun and part shade.

Panicum virgatum (Switchgrass) grows along streambanks in sun or part shade.

Tripsacum dactyloides (Eastern gamagrass) likes part shade and grows in moist areas or along streambanks.

Cephalanthus occidentalis (Common buttonbush) grows in moist areas and will grow in standing water in shade or part shade.

Salix humilis (Prairie willow) grows in sun along streambanks.

Salix nigra (Black willow) grows in sun, part shade and shade along streambanks.

Sambucus nigra ssp. canadensis (Common elderberry) grows in part shade and is good for erosion control in moist areas.

Forestiera acuminata (Eastern swamp-privet) will grow in moist soil or standing water in part shade.

Alnus serrulata (Hazel alder) grows in sun, part shade and shade on stream banks and other wet areas.

Here are photos from our Image Gallery:

Andropogon glomeratus

Andropogon virginicus

Carex blanda

Carex cherokeensis

Chasmanthium latifolium

Cladium mariscus ssp. jamaicense

Panicum virgatum

Tripsacum dactyloides

Cephalanthus occidentalis

Salix humilis

Salix nigra

Sambucus nigra ssp. canadensis

Forestiera acuminata

Alnus serrulata