Moss is a common problem in the Pacific Northwest. It grows thickly on roofs, in lawns, and on shady sidewalks. Beautiful where it is wanted, but it can damage roofs. There are no safe chemical measures to remove moss from a roof. Gentle physical removal is best. For lawns, gradually raising the pH of the soil will discourage it, but many people love the look of moss as a groundcover. It is certainly a low maintenance option....