I live in New England (zone 3-4) and have a very steep hill currently
planted in grass (a real pain to mow) that terminates in woodland. I
would like to get rid of the grass and plant either day lilies, or
else some kind of ground-cover that will prevent erosion but need
little maintenance as the hill is almost too steep to walk on. The
area is about 100 yards long by about 15' from the shoulder of the
hill to the woods. The drop is about 10 feet from the shoulder at the
steepest point. Any suggestions about how to do this and what to use
would be greatly appreciated.

Thanks