The green film on your siding is algae, usually mixed with mildew, and in Central Kentucky humidity it shows up first on north facing walls and the shaded sides of your house.
Lexington sits in the right mix of humidity, mature tree canopy, and warm summers for algae to love your siding. Shaded walls never fully dry out, so the growth gets a head start there. You will see it worst in older tree lined neighborhoods like Chevy Chase, Kenwick, and Ashland Park.
Household cleaners and a scrub brush will not fix it. Those products are not strong enough for exterior growth and used wrong they can set stains permanently. A garden hose just feeds it more water.
A soft wash kills the algae and mildew at the root and rinses it away without harming the siding, your plants, or your paint. Most homes stay clean for one to two years afterward. Shaded walls may need attention on the shorter end of that range.
Answer last updated August 12, 2026.
More detail, photos, and what's included: House Washing in Central Kentucky.
