Spray the vinyl deck with a garden hose to wash away dirt and loose debris.
Add liquid dishwashing soap to a bucket of warm water.
Apply the soap solution to the deck.
Scrub the vinyl with a scrub brush working the soap into any dirt or residue. The soap will break up residue, making it much easier to remove and wash away.
Reapply the soap solution to the deck, working in small sections, until the entire deck is covered. Scrub away remaining stains.
Rinse the deck with the garden hose to remove soap and dirt.