Diana, Please don't go grinding up lichens to include in your spray...they are sometimes VERY slow growing. The old saw about buttermilk is usually meant to encourage the growth of moss. In most places it probably works just as well to leave things alone. If conditions are right to favor moss production, there's plenty of it floating around... Carlo Carlo A. Balistrieri (carlob@ridgewoodpower.com) The Gardens at Turtle Point 79 Turtle Point Road Tuxedo Park, NY 10987 Zone 6 (845.351.2049)