We just did this process; used vinyl siding cleaner boosted with bleach and a soft brush on a 12' pole. We have EXTREMELY high places on our house, and at a few stages were hanging out the upstairs bathroom window with the pole/brush - it must have been hysterical to see. We have found the bleach is key. The siding cleaner alone doesn't cut it. Everything below (gardens, deck, etc.) was covered with tarps, we brushed it all with the solution, then hit with a power washer (we were also hanging out the window with that!). It was a whole afternoon for the one north facing side of the house, but it's worth it!