Green algae on siding is super common — especially on the shaded, damp side of a house. The “zero-effort” trick most neighbors swear by is usually one of these two methods:
🧼 The 10-Minute Spray Method (No Scrubbing)
What you need:
- Outdoor bleach (or regular household bleach)
- Water
- Pump garden sprayer
- Optional: a little dish soap
How it works:
- Mix 1 part bleach to 3 parts water in a pump sprayer.
- Add a small squirt of dish soap (helps it cling).
- Lightly spray the green areas — don’t soak excessively.
- Let it sit for 10–15 minutes.
- Rinse gently with a garden hose.
The algae usually fades and disappears within a day. No scrubbing needed.
🌿 The “Even Easier” Option: Wet & Forget
Some people use products like Wet & Forget.
You spray it on and literally walk away — rain gradually washes the dead algae off over a few weeks.
⚠️ Important Tips
- Never mix bleach with other cleaners.
- Protect plants by wetting them with water before and after spraying.
- Avoid pressure washers on vinyl siding — they can force water behind panels.
- Test a small area first.
Why algae grows there
- North-facing walls
- Heavy shade
- Humid climates
- Poor airflow
If you tell me what type of siding you have (vinyl, wood, brick, stucco), I can tailor the safest version of the trick so you don’t accidentally damage it.
