- Wet the black spots on your cedar deck with a garden hose, or spray the entire deck to remove dust and dirt.
- Mix 1 tsp. liquid dish soap into a gallon of water and mix it well. Dip a stiff-bristle brush into the cleaning solution and scrub the black marks with the soapy brush.
- Mix 1 part chlorine bleach with 4 parts water in a clean bucket. Wet a sponge with the solution and apply it to the remaining black marks on your cedar deck. Let the bleach sit on the mold for 10 minutes to kill it.
- Rinse the bleach solution from the cedar deck with a garden hose and inspect the black marks. Reapply the bleach solution to any marks that remain. Leave it on for 15 minutes before rinsing it off completely.
- Sweep all standing water from the deck after rinsing it, which will help the deck to dry faster.
Things You Will Need
- Garden hose
- Liquid dish soap
- 2 buckets
- Stiff-bristle brush
- Remove wet leaves and other debris from cedar decks as soon as possible to reduce black mold marks.