I am located in central PA. I have steep banks on each side of my driveway that have a lot of bare spots. The tallest is about 20 feet high. The driveway itself faces south so both banks get a good dose of direct sun throughout the day. I am looking for recommendations for what I can get to "spread" on the bank surface that will take hold and provide cover for the big bare spots. Crawling up on the bank and "planting" anything is out of the question as the soil is rather loose and easily eroded. I need something that will take hold just from being tossed or spread on the surface of the bank. I would also prefer something that is pretty much self maintaining that won't require cutting or trimming and that is friendly and won't eventually expand and encapsulate the house. :-)
Below are two photos to give you some idea of the slope and existing growth.