How to Remove Algae From Your Exterior Wood

Now that it’s officially patio season, it might be time to take your spring cleaning one step further: deep cleaning. Why? Over the winter and spring months, a lot of unsightly things can happen in your treasured outdoor space. Worse than typical leaves, dirt, and mud — and harder to get rid of — is algae.

What is algae, exactly? Why does it grow on exterior wood surfaces? We’re breaking down what you need to know about algae and how you can safely remove them just in time for summer. 

What is algae?

You’ve probably seen it before: a green, slimy film that somehow finds its way onto virtually any exterior surface — your deck, wooden furniture, and even your siding. That’s called algae, and like moss and mold, they can be damaging to wood.

Biologically speaking, algae is not a single thing. They are a group of aquatic organisms that produce oxygen through photosynthesis. Although algae don’t have roots, leaves, or stems, they function similarly to plants. Despite producing oxygen and providing tons of other benefits for the environment, algae can be harmful to any home exterior surface it grows on. 

How does it grow on exterior wood?

Algae thrive in dark and wet conditions, which is why you’re likely to see them appear after darker and wetter seasons (like winter and spring). This is especially true for wood surfaces, which soak in moisture for days at a time, becoming the perfect home for algae to settle in.

However, algae aren’t limited to just exterior wood surfaces. They can also grow on virtually any surface that’s exposed to the right combination of elements — siding, patio furniture, windows, stone, and more. 


The reason algae are particularly harmful to exterior wood? Their moisture can seep deep into the wood, causing it to warp and splinter. Because of their slimy texture, algae can cause extremely slippery surfaces, increasing the chances of someone falling and hurting themselves.        

How do you remove algae from wood?

Thankfully, algae doesn’t have to be a persistent headache or damaging to your exterior wood surfaces. In fact, with the right products, you can do a deep cleaning to remove it — without the extra time and effort that deep cleaning often involves. We’ll call that a win.

Photo of wooden deck with outdoor table and seating area.

For your first ‘deep’ clean of the season, WOCA Exterior Cleaner is an incredibly effective and safe option for all of your exterior surfaces — not just wood. It can be used on:

  • Wooden decks
  • Patio furniture
  • Brick
  • Stone pavers
  • Siding
  • Outdoor tile
  • Concrete

What’s more, it not only removes algae (and other harmful growth like mold, moss, and stains), but it protects your surfaces from any regrowth. All it takes is a few steps, and your outdoor space will be closer to ready!

  1. Soak the surface with a hose.
  2. Dilute WOCA Exterior Deck Cleaner with 1 part solution to 2 parts water.
  3. Apply solution with a scrub brush or spray, then scrub lengthwise with the surface grain until it appears clean.
  4. Repeat if necessary.
  5. Rinse the surface with water immediately after cleaning.
  6. Leave the surface to dry for 24 hours. Before applying any protective treatment, like Woca Exterior Oil, or other products, the wood must be completely dry.  

Pro tip: If your surfaces need regular cleaning throughout the summer, our Exterior Deck Cleaner is safe to use around plants (when diluted)!

If your wooden patio or furniture needs an extra deep clean, you can also check out WOCA Deep Cleaner, which is best for getting rid of oil and dirt on wood surfaces only.

Remove Algae from Your Exterior Wood Surfaces with WOCA

Getting your patio summer-ready doesn’t have to require the effort of a deep clean, but you can still get the results of one. With WOCA’s safe and environmentally friendly products, you can keep your outdoor living space and exterior wood surfaces algae-free year-round. Explore our outdoor collection now, so you can have more time for relaxing later!

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