Remove any surface dirt from the fabric furniture with a dry scrub brush.
Mask the non-fabric parts of the furniture with painter's tape if the fabric cushions aren't removable. Lay down a dropcloth and place the furniture or cushions on top. Spray a small amount of UV fabric protector spray on a small hidden patch of the fabric to test colorfastness. Dab the area with a white paper towel. If no color wipes off, the spray is safe to use on the fabric.
Spray a thin layer of UV fabric protector spray over the surface, holding the can 12 inches away from the fabric. Allow the coat to dry for a half hour. Repeat 2 to 3 times, until the dried treated fabric repels a drop of water.
Place cloth furniture in a shaded area for further protection. Store removable cushions out of the sun when they are not in use.