Here are some special vinyl siding cleaner products you can buy at most home improvement box stores like Lowe's, Home Depot and Walmart.
Expert Chemical House Wash Home Depot $18
Mold Armor House cleaner and mildew killer. Application method, hook to hose and spray. 56 oz.
Simple Green House and Siding Cleaner
TSP or Trisodium Phosphate. Home Depot
Soft Bristled Brushes
Telescoping aluminum poles. Comes in several different lengths.This is a good tool to buy and keep around the house. You can attach many different attachments to it like paint rollers and window squeegees.