Wet & Forget Outdoor Moss, Mold, Mildew, and Algae Stain Remover Concentrate, 128 oz

I've used this in the past and it does a great job. You just spray it on and wait until it rains. The rain washes the siding or wood and most if not all of the dirt will be gone after one to two rains. It is so much easier to use than pressure washing everything. I used it on my wooden fence and it did a wonderful job. Also have used it on siding and again it is much easier than having to pressure wash. I highly recommend this product.

Have used this since 2016 on my sidewalks and driveway. Just once a year and it stays looking like new. If it is really bad you may want to powerwash first time, then spray it for faster results. After that I just spray it once a year and it stays new looking. Graveyards are the best for letting it work over time and don't have to scrub anything - just spray and go. The attached pictures show what just two sprays can do to a grave.