Ask Mr. Smarty Plants

Depending on how steep your slope is, you might benefit from using some sort of erosion control blanket. The erosion-control fabric works by slowing the runoff water and allowing sediments to fall out rather than be washed away. Seeds sown under the erosion-control material 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.  Most nurseries carry these erosion control blankets.

For plant recommendations, let's start with grasses since the extensive fibrous roots of grasses are very effective in holding soil in place. Since I don't know anything about your site's available moisture and soil composition, you will need to read the "Growing Conditions" area of each species to be sure they are compatible with your site.  I  have chosen plants native to Iowa that will grow in shade (less than 2 hours of sun per day).

Grasses and grass-like sedges:

Carex blanda (eastern woodland sedge)

Chasmanthium latifolium (Inland sea oats)

Muhlenbergia schreberi (nimblewill)

Digitaria cognata (fall witchgrass)

Carex pensylvanica (Pennsylvania sedge)

Herbaceous flowering plants:

Asarum canadense (Canadian wildginger)

Aquilegia canadensis (red columbine)

Hydrophyllum virginianum (eastern waterleaf)

Rudbeckia hirta (blackeyed Susan)

Maianthemum racemosum ssp. racemosum (feathery false lily of the valley)

Ferns:

Athyrium filix-femina (common ladyfern)

Dryopteris cristata (crested woodfern)

Polystichum acrostichoides (Christmas fern)

You can search for more plants that meet your criteria by visiting our Iowa Recommended page.  You can use the NARROW YOUR SEARCH option on the sidebar to make choices, e.g., select 'Shade..." under LIGHT REQUIREMENT.