Leaving cushions on outdoor furniture permanently is generally not recommended. While convenient, constant exposure to the elements significantly shortens their lifespan. Sunlight causes fabrics to fade and become brittle, while rain and humidity lead to mold, mildew, and internal foam damage. Wind can blow cushions away or cause undue stress.
For optimal care, it's best to bring cushions indoors or into a dry storage area after use. If daily storage isn't practical, invest in high-quality, weather-resistant cushions designed for all-season use and employ protective measures. Using durable, solution-dyed acrylic fabrics and quick-dry foam inserts is crucial. Always utilize a waterproof storage bench or deck box for convenient nearby storage. For furniture left outside, a high-quality, waterproof furniture cover that breathes is essential to minimize moisture buildup.
In summary, while you *can* leave them out with the right products and covers, bringing cushions in when not in use, especially for extended periods or in harsh weather, is the surest way to protect your investment and keep your outdoor space looking its best.