Cleaning/power washing the wall behind the house
 

The wall adjacent to our property has started to mildew/mold.
Looking for something to spray on that will clean it up.

My second choice is to have it power washed.

Looking for suggestions.

I do not know how long you have been in your home, but here in The Villages you will find that mold and mildew will be an issue on many outdoor items such as walls like yours, your house surface, gutters and downspouts, outdoor furniture, lawn rock walls etc. I personally have used a product called Krud Cutter House and Siding wash. You can use that with a Pump Spayer or Power Washer. It is a concentrate that you can buy in a 1 Gallon container.

I typically use a hand pump sprayer with a two-gallon tank. I spray on and use a long handle brush and then hose it off. I also have a small power washer that I can use. Some neighbors joke that I can hire someone to do it, but I find some joy in doing this type of task as long as I am capable.

Krud Kutter® House and Siding Pressure Washer Concentrate
Item #121210
$17.99 ea
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House and Siding Pressure Washer Concentrate contains a proprietary blend of ingredients to remove tough stains from mildew, mold, algae, fungus and moss, and leaves the surface completely clean.

Depending on how bad? you may be able to spray Clorox cleaner + bleach on it set it set for few minutes and wash it off with hose. I had to scrub few spots that was darker.

https://shop.clorox.com/products/clo...cleaner-bleach

Or you can just mix 10% bleach water (wearing gloves) and scrub it in and rinse off.

If you got long wall and years old mold build up bleach water and pressure washer probably only option?

Try "Wet and Forget Outdoor" instead of power washing.
 

I gave up on the big local power washing company because it was getting too expensive, quality was suffering and charged extra for every little thing.
Had them annually (sometimes twice per year) for years. Vinyl sided house.

Tried "Wet and Forget" 3 years ago for the whole house and am pleased. Spray it on with garden hose and leave it. I do it once per year.
It works slowly and house looks great.
Link below
https://www.wetandforget.com/wet-and...-hose-end.html