Zinc-Sulfate for Moss Control on a Tile Roof

Moss Growth

• Shade and moisture give moss the opportunity to grow. The spores travel through the air until they find a suitable home. A nearby tree that blocks the sun from warming and drying the tile is an ideal condition for moss growth, giving it the opportunity to gain a foothold and rapidly expand. Killing it with zinc sulphate is inexpensive, quick, highly effective and long-lasting.

Dangers

• Zinc sulphate is available at most hardware stores and is safe to use when directions are followed. It's toxic to animals or plants and is classified by the Environmental Protection Agency as a pesticide. Zinc should be stored safely away from young hands and used only when there is no wind to cause drifting onto plants or areas with water features.

Application

• A normal application of zinc sulphate would be 3 lbs. for a 600-square-foot roof. It comes in powder form and is sprinkled directly onto the moss and other roof areas. It can also be mixed with water and sprayed onto the roof. A water spray is as effective short-term as the powder, but since it is not as long-lasting, it might have to be reapplied annually. Cover surrounding plants and shrubbery with tarps when spraying zinc sulphate.

Quick Action

• Within three weeks, most moss on a roof treated with zinc sulphate will turn dark brown or black and be dying. It then can be brushed off the roof. Zinc kills moss down to the roots and might keep it away for up to five years with one treatment. It does not stain most materials and is not slippery after application. The zinc may look white after the application, but the color will quickly go away after a light rain.