Remove cushions or pillows from the redwood furniture. Wet the furniture with water from a garden hose, drenching it completely.
Mix 1/4 cup ammonia into a quart of warm water in a bucket. Add 2 tbsp. white vinegar to the mixture and stir.
Dip a soft-bristle brush into the cleaning mixture, wetting the entire scrubbing tool. Scrub the redwood furniture with the brush, using medium force. Clean the wood between the slats in the furniture. Turn the furniture over and wash the bottom area also.
Rinse the cleaning solution thoroughly from the redwood furniture with the garden hose. Flip the furniture over and rinse the top side.
Place the redwood furniture in the sun to dry. Place back onto the patio, deck or porch after drying.