Pour 2 to 3 cups of undiluted distilled white vinegar into a large bowl or bucket.
Dip the bristles of the hard-bristled brush into the white vinegar. The bristles should be completely soaked.
Scrub the area of lawn furniture covered with mildew.
Allow the white vinegar to sit on the lawn furniture for roughly 15 to 30 minutes.
Rinse the lawn furniture with water.
Dry the lawn furniture with a clean, dry towel or let the lawn furniture air dry. Make sure the lawn furniture is completely dry before you put the piece away.
Repeat the process if you believe any mildew remains on the lawn furniture.