There are various products like Iron Out and Rust Out, but whether they will bring your vinyl (?) siding back to the original color is another matter.

I would re-direct the the sprinklers and look for some matching siding pieces and replace them. Another cheap fix is to paint the affected area.

Hi Brian!

I know I have mentioned this product years ago. It is called whink. I did spell it right as I am looking at it. You should be able to find it in your laundry section at you local food store. It is a brown, 6 oz. bottle. You may need several if this is a large area. You can always use them for your launrdy if you purchase too much. Just soak an old face cloth and give it a wipe and see what happens. This stuff works like Tarnex on silver, the reaction is instant! I had a friend use this years ago on her blue siding. The directions tell you that this should be used on white sinks only, etc. It worked for her and all she needed was to replace the rubber gasket in her garden hose. Don't hose this off but use a bucket of water with Dawn and wash it 2 or 3 times and your plantings should be fine. Just don't let it run into the soil. Use WV to rinse it followed with clean water. Let us know your out come.

Graywings did give you 2 great suggestions but the Rust Out does not work any longer. The EPA poked their nose in and they had to change the formulation. Let's save the world! I don't clean Green and don't care! Rust Out used to work when it contained Hydrofluoric Acid. I have an old, empty bottle and 6 new ones and it does not work as the EPA poked their noses in to clean up the world. whink still contains it so it works.

Good luck and let us know!

So that's the problem with Rust Out! With our bad well water I buy rust stain removers by the gallon.

I have been using RustAid liquid for the outside in a spray bottle and Iron Out powder on the inside (add to toilets and sinks).