What is that green stuff on my vinyl siding? Great question! That green stuff is Algae and Mold. Algae and mold love to grow in shady places. Often you will notice the siding start to get dingy and dirty looking. It appears mainly on the North side of your property and in any heavily shaded areas. The image posted is a Before & After from a vinyl siding softwash cleaning. We use a environmental friendly cleaner to kill and clean the algae and mold from your siding.