My neighbor taught me this trick to clean green algae off siding with 0 effort. Here’s how it works
Green staining is often algae, but dark or fuzzy growth can sometimes be mildew, mold, moss, or another type of biological growth.
If staining keeps returning unusually quickly, covers a very large area, or appears to be associated with water entering the wall, investigate the moisture source rather than repeatedly cleaning the surface.
The Bottom Line
The easiest way to remove green algae from siding is often not aggressive scrubbing at all.
Apply a siding-safe cleaner, give it enough time to loosen the growth, gently brush only where necessary, and rinse thoroughly.
The real secret is contact time rather than force. Once the cleaner has done its work, much of the algae can often be removed with surprisingly little effort.
