30 Seconds Spray & Walk Away Hose End Concentrate is intended for use on paths, roofs, brickwork, and other large hard surfaces, as well as walkways, walls, wood, paving, cloths, plastics, and concrete to target and kill moss, algae, lichen, and mold.  This product is safe around gardens and planting areas, but is not meant for direct application to plants.  Typically lichen grows because of the inability of the affected areas to dry out, usually trimming back and thinning to get more sunlight will help reduce lichen growth on plants. For product support and further clarification, the manufacturer can be reached directly at (503) 669-1953, or via their website's contact page here.