HG Algae & Mould Remover removes the familiar mould, algae or lichen from patios, paths, walls, roofs, fences and terra cotta pots, etc. After application the area will be clean within 36 hours. The cleaner goes deep into the surface, protecting it against re-growth for months at a time. 

HG algae and mould remover is of course not harmful to your grass and plants.