To clean your home's siding, use a pressure washer, or scrub the siding with a soft-bristled brush using a mixture of 1 gallon of water, 1/3 cup of powdered laundry detergent and 2/3 teaspoon of trisodium phosphate cleaner. Work from the bottom to the top, rinsing the siding as you go.
When using a pressure washer, hold the nozzle straight instead of at an angle. If you spray at an angle, the water can get under the siding and cause damage. Choose the setting carefully so you don't use so much pressure that it causes damage. Be careful near windows and doors.
Use a soft-bristled brush if you clean the siding by hand to avoid damage to the surface. A long handle on the brush allows you to reach more of the siding without moving your ladder. Avoid using harsh cleaners or abrasive cleaning tools such as steel wool, as they could cause scratches or discoloration.
For tough stains or mold on the siding, mix 1 cup of oxygen bleach with 1 gallon of water. Oxygen bleach is safer for landscaping plants near the house than regular bleach or harsh cleaners. Wetting nearby plants or covering them with plastic also helps protect them from bleach and cleaners used on the siding. Rinse any cleaners thoroughly so they don't leave behind streaks.