Outdoor sofa cushions can develop an unpleasant musty smell due to moisture, mold, or mildew. To keep them fresh, follow these tips:

1. Store Properly: When not in use, store cushions in a dry, ventilated area. Use breathable storage bags to prevent trapped moisture.

2. Clean Regularly: Wash cushion covers with mild soap and water, and let them dry completely before reassembling. For mildew, use a vinegar-water solution.

3. Use Waterproof Covers: Invest in waterproof or UV-resistant cushion covers to protect against rain and humidity.

4. Elevate Cushions: Place cushions on raised surfaces or use slatted furniture to improve airflow and reduce moisture buildup.

5. Apply Baking Soda: Sprinkle baking soda on cushions to absorb odors, then vacuum it off after a few hours.

By following these steps, you can extend the life of your outdoor cushions and keep them smelling fresh all season long.