How to Remove Green Algae From Vinyl Siding

Green algae on vinyl siding
As part of routine home care, it's important to inspect your siding for signs of wear or damage and to keep it clean in order to maintain the appearance and longevity of this durable material. As with any type of exterior finish, vinyl siding can become dirty over time due to an accumulation of dirt and grime, most of which can be removed with a simple spray of the hose—but if you notice the appearance of green stains during your inspection you'll need to take a different approach. Read on for some valuable tips for how to remove green algae from vinyl siding, from the knowledgeable professionals at Five Star Painting®.

What Causes Vinyl Siding to Turn Green?

Since it was first introduced in the late 1950's vinyl siding has gained popularity due to its versatility, strength, and ability to weather the elements. However, while the polymer material may be able to withstand high winds and harsh UV rays it is still susceptible to staining, including a green discoloration caused by one of the following:


Mold growth can occur when there is an ongoing issue with water leakage or improper drainage, from sources such as a drainpipe or gutters. Once the necessary repairs or adjustments have been made the mold removal can begin, but because mold can be difficult to remove and might require the use of harsh chemicals you may want to consult a professional for assistance.


Algae growth typically occurs in areas where dirt and dust have collected, as the organic material is used as a source of food. The algae may appear brown or green in color and remain damp, diminishing the appearance of your home and spreading out over time. Unlike mold, this type of growth is mainly cosmetic and can be removed using minimal force and a few basic materials.

How to Remove Algae From Siding

1. Gather your materials.

You will need:

  • Duct tape
  • Plastic sheeting
  • Large bucket
  • Garden hose with a spray attachment or power washer
  • Oxygen bleach
  • Long-handled scrub brush
  • Water resistant footwear and gloves

2. Safeguard the exterior.

Protect vulnerable entry points on your home's exterior such as electrical outlets, exhaust vents, and more by covering them or taping them closed with duct tape. Use plastic sheeting over top of plants and landscaping that are in close proximity to the home, and ensure all doors and windows are closed.

3. Mix your cleaning solution.

Fill a bucket with warm water and mix in the oxygen bleach powder according to the package directions.

4. Test a small area.

Dip the scrub brush into the solution and test it to see if it is effective at removing the staining. If not, the green discoloration may be mold.

5. Apply some elbow grease.

Begin at the top of the house and work your way down, dipping the scrub brush into the mixture and applying force with a side to side motion. Divide the project into manageable, 20-foot sections, rinsing each one well from the top down once completed.

Keep your home looking its best all year round with high-quality painting services from the team at Five Star Painting. Contact us today to schedule your free estimate or call (888) 261-3633 and let us know how we can help.