If your patio is shaded and moist, you may soon begin to notice a green carpet-like plant spreading across its surface. This is moss. Though not inherently harmful, moss can stain your patio surface and is also slippery, creating hazardous conditions on your walking surfaces. Clean your patio immediately to kill and remove moss and restore the beauty and safety of your patio.
Knock off as much of the moss as possible with a stiff-bristled brush or broom. Use brisk, short scraping movements. Pile the moss into a container or bag and discard to prevent moss spores from spreading.
Spray the entire patio -- not just the moss, as invisible moss spores may be on other areas of the patio -- with any moss control and cleaning solution formulated with potassium salts of fatty acids, which both kills the moss and also lifts the moss from the patio due to the acids' soap-like consistency. Apply according to the product label's guidelines, as chemical concentrations vary by product.
Allow the solution to sit on your patio for the time listed on the product's label, typically ranging from 15 to 30 minutes. This gives the potassium salts of fatty acids time to penetrate the growths.
Rinse down the patio. Use a standard water hose or, for faster cleaning, a pressure washer. Spray down the entire patio to rinse away the potassium salts of fatty acids and the dead pieces of moss.