While covering your outdoor furniture provides significant protection, it's generally not advisable to leave cushions outside permanently, even on covered patios. The primary reason is moisture. Covered areas are still exposed to humidity, blowing rain, dew, and condensation, which can lead to mold, mildew, and internal damage to cushion foam. Covers can also trap moisture underneath, creating a damp environment.
For optimal care and to extend the life of your cushions, the best practice is to store them indoors or in a waterproof storage box when not in use for extended periods, especially during harsh weather or off-seasons. If you must leave them out, ensure they are on fully covered, dry furniture and use breathable, waterproof furniture covers designed specifically for cushions. Always allow cushions to dry completely before covering them. Regularly cleaning and airing out your cushions will also help prevent deterioration and keep your outdoor living space fresh and inviting.