How to Remove Green Algae & Black Mold From Your Siding
That green film and those dark streaks creeping across your siding aren't just dirt — they're living organisms. And if you've tried scrubbing or spraying bleach, you've probably noticed they come right back. Here's why, and what actually works in the humid Lowcountry.
What's actually growing on your siding
The green coating is algae; the darker grey and black patches are mildew and mold. All of them feed on moisture, pollen and organic debris — exactly what Hilton Head, Bluffton and Okatie homes get plenty of thanks to humidity, shade and salt air. Left alone, they spread, stain permanently and hold dampness against your siding.
Why bleach and scrubbing don't work
- Bleach only masks it. Household bleach can lighten the stain for a few weeks but doesn't kill the root, so it returns — and it can harm your plants and discolor surfaces.
- Scrubbing spreads spores. Hand-scrubbing is exhausting, uneven, and pushes spores into new areas.
- DIY pressure washing damages siding. High pressure forces water behind panels and can crack older vinyl — without killing the organism. (Here's why soft washing is safer than pressure washing.)
The professional solution: soft washing
Soft washing applies a biodegradable cleaning solution at low pressure that kills algae, mold and mildew at the root. Once the organism is dead, a gentle rinse leaves your siding clean — and because the spores are eliminated rather than just knocked loose, the results last months longer than any DIY method. Your landscaping is protected throughout with pre-wetting and thorough rinsing.
Lasting results, not a quick rinse. The difference between soft washing and a cheap power wash is the difference between killing mold and simply hiding it. That's why a proper soft wash keeps your home cleaner far longer.
How to keep it from coming back
Once your siding is clean, an annual maintenance wash keeps mold and algae from re-establishing. Homes in heavy shade or near the marsh may need it more often — see our guide on how often to soft wash your house.
Frequently asked questions
What is the green stuff growing on my siding?
It's algae; darker patches are mildew or mold. All thrive in humid, shaded conditions and keep spreading until killed.
Does bleach remove mold from siding?
Only temporarily — it lightens the stain but doesn't kill the root and can harm plants. Soft washing kills it for good.
Can I remove mold from siding myself?
You can spot-treat small areas, but DIY pressure washing risks damage and rarely kills the organism. A professional soft wash is safer and lasts longer.
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Safe, lasting mold and algae removal for Hilton Head, Bluffton & Okatie homes.
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