I have been filling in a long driveway with trees and shrubs but am stuck on the edge. What perennials and subshrubs look fine without being cut back? Im looking for deer resistant, hardy in zone 6 suggestions. Among plant material i have avsilable to divide are siberian iris, caryopteris, russian sage, nepeta, lambs ears, dianthus, but open to any ideas. If there is no such thing as maintenance free perennials, i will just continue with groundcovers like pachysandra, geranium, and ferns.