If you’ve lived in Florida for more than a year or two, you’ve probably noticed it.
One day your house looks bright and clean. A few months later, you start seeing faint green patches on the siding. Maybe they’re around the gutters. Maybe they’re on the north side of the house where the sun doesn’t hit as often.
One of the most common questions I hear after 22 years in the exterior cleaning business is: “Why is my house turning green?”
It’s Not Dirt, It’s Living Organisms
Most of the time the green stains are algae, mold, mildew, or a combination of all three. Florida’s warm temperatures, heavy humidity, frequent rain, and long growing season create the perfect environment for these organisms to thrive.
Why Does It Always Start on One Side of the House?
The north facing side of a home usually receives less direct sunlight, meaning it stays damp longer after rain. Homes surrounded by mature trees or exposed to sprinklers also develop buildup faster.
Is It Just Ugly, or Can It Cause Damage?
Organic growth traps moisture against your home’s exterior. Over time that can contribute to premature paint failure, wood deterioration, mold growth, surface staining, and a shorter life for exterior materials.
Why Pressure Isn’t Always the Answer
Most siding doesn’t need high pressure. Professional soft washing uses specialized cleaning solutions to kill algae, mold, and mildew before gently rinsing the surface clean. It’s safer and produces longer lasting results.
Can I Clean It Myself?
Sometimes. Small concrete areas are often reasonable DIY projects. House siding is different. Experience matters because knowing what not to do is just as important as knowing how to clean.
How Can You Prevent It?
Trim back trees, adjust sprinklers, clean gutters, schedule routine exterior cleaning, and monitor shaded areas after rainy seasons.
A Lesson I’ve Learned After 22 Years
Homeowners almost never call when algae first appears. They call months later. After we finish cleaning, many say, ‘I forgot my house was this color.’
The Bottom Line
If your house is turning green, don’t assume it’s just dirt. Addressing organic growth early is easier and helps protect your home’s exterior for years to come.
