The first step is to sweep or brush off loose dirt, leaves, etc.
Make DIY composite deck cleaner by adding 1 cup of white vinegar to a gallon of warm water. Dump in 1/4 cup of baking soda. Make sure you are using a large enough bucket because your vinegar and baking soda will fizz.
Spray the surface of the deck with a garden hose first.
Dip soft bristle brush in homemade deck cleaner and sweep on. We were shocked how it naturally broke down the mildew.
Work in small sections and spray off each area as you finish.
Enjoy your beautiful and clean deck.
Video
Notes
Work in small sections.
Make sure to fully rinse your decking before and after.
Always test cleaning solutions in a small area first to make sure it is safe for your specific deck.