Purchase a spray canister at a hardware store. Look for the same type of sprayer marketed for use with insecticides.
Mix in the spray canister three quarts of water, one quart of bleach and one-quarter cup of liquid dishwasher detergent that is ammonia free. The bleach will kill the mildew and the detergent will help to remove any dirt and mildew remnants.
Spray the cedar thoroughly. Let the solution sit for10 to 15 minutes to allow time for the bleach to kill all the mildew.
Rinse with a hose or pressure washer. Repeat the treatment if necessary to ensure that all the mildew is removed. Allow the wood to dry completely for one or two days.
Treat the cedar with a water-repellent stain or preservative that contains a mildew-repelling agent, if you are able to. You can use this type of product on cedar decking and siding.
Things You Will Need
- Spray canister
- 3 quarts water
- 1 quart bleach
- ¼ cup liquid dishwasher detergent
- Hose or power washer
- Wood stain or preservative (optional)
- Apply a sealant or wood stain only after you've rid the cedar of mildew completely. If any mildew is still present, it will grow through the stain and continue to spread.