Put on goggles and rubber gloves. Scrub the fabric on the furniture, using a brush, to remove the loose mildew and mold along with surface dirt and pollen.
Pour 1 gallon of clean water into a bucket. Mix in 1/2 cup of chlorine bleach, if the furniture fabric is white. Mix in 1/2 cup of color-safe, nonchlorine bleach, if the furniture fabric is colored.
Dip a cloth into the bleach/water mixture, and wipe the mildew stains on the furniture with the cloth. Allow the mixture to soak into the fabric for about 10 minutes.
Rinse the stain fully with water from a garden hose. Allow the furniture to dry in the sun.