White mildew spots on outdoor furniture cushions are a common problem caused by moisture and lack of airflow. To effectively remove them, start by taking the cushions outside on a sunny day. Brush off any loose spores with a stiff brush. Create a cleaning solution by mixing equal parts white vinegar and water in a spray bottle. Alternatively, you can use a mixture of 1 tablespoon of dish soap with 1 quart of warm water. For tougher mildew, a solution of 1 cup of bleach mixed with 1 gallon of water can be used, but test it on a small, hidden area first to check for colorfastness.
Spray the chosen solution generously onto the mildewed areas. Let it sit for 10-15 minutes to penetrate and kill the mold. Scrub the surface thoroughly with a bristle brush, paying extra attention to the spotted areas. Rinse the cushions completely with a garden hose to remove all the cleaning solution and loosened mildew. It is crucial to let the cushions dry completely in direct sunlight. The sun's UV rays help to kill any remaining mold spores.
To prevent mildew from returning, store cushions in a dry, well-ventilated area when not in use, especially during rainy or humid weather. Using waterproof covers or storing them indoors can significantly help. Regularly cleaning your cushions and ensuring they are completely dry before storage are the best practices for long-term maintenance.