Homemade cleaner for outdoor algae moss mold & mildew

Updated February 21, 2017

Commercial cleaning products cost an arm and a leg and are often full of toxic chemicals that can be harmful in the home, or nature. Spring brings tulips and cherry blossoms, sun and warmer temperatures and a host of green ickies blooming on our wood, furniture and siding. The wet, warm season is an incubator for all that is slick and slimy, and cleaning these off is part of returning to the outdoors. There are a host of commercial products that claim to clean the unwanted growths, but your own home holds the key to less toxic and cheaper alternatives.

Sweep off any dirt and debris on the surface you will be cleaning. This solution works best if you can apply it on a dry day and on a dry surface. If you are cleaning a deck, remove pots, furniture and other items that are on the wood.

Don eye protection and gloves. Mix 1 gallon of warm water, 1 1/2 cups trisodium phosphate and 8 cups of bleach in a 5-gallon bucket. Stir the mixture until the trisodium phosphate dissolves.

Dip the long-handled scrub brush into your cleaning solution and scrub the dirty area. Scrub wood surfaces a bit more gently than cement or they may splinter. The cleaner will penetrate into porous surfaces and remove the mould, mildew, algae and moss.

Rinse the deck completely and use the nozzle end to loosen any moss that remains. The stains and plant growth will be gone, but if you want to lighten up the surface more, let the area dry and reapply.

Prepare the surface that needs to be cleaned by sweeping or spraying it off with water. Loosen any large chunks with a broom or long handled brush. Sweep them up in a dustpan.

Pour 3 tbsp of dish detergent, 2 cups of bleach and 1 cup of alcohol into the 5-gallon bucket and add 1 gallon of water. Stir the mixture until everything is incorporated.

Dip the long-handled brush into the cleaning solution and scrub it onto your surface. Scrub in the direction of the grain on wood surfaces. Try not to splatter the mixture onto plants as the bleach will burn the leaves. Rinse the area completely and allow it to air dry.


For an environmentally safer cleaner, use an oxygen bleach. The cleaning power is not as strong as regular liquid bleach so you will have to apply at least twice to get the results you want.

Things You'll Need

  • Broom
  • Dust pan
  • Long handled scrub brush
  • Eye protection
  • Gloves
  • 5-gallon bucket
  • 1 gallon warm water
  • 1 1/2 cups trisodium phosphate
  • 8 cups bleach
  • Paint stirrer
  • Hose with spray nozzle
  • 3 tbsp dish detergent
  • 2 cups bleach
  • 1 cup rubbing alcohol
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About the Author

Bonnie Grant began writing professionally in 1990. She has been published on various websites, specializing in garden-related instructional articles. Grant recently earned a Bachelor of Arts in business management with a hospitality focus from South Seattle Community College.