That's an excellent and very practical question! The answer, like many things in life, is: it depends. Whether you can leave your outdoor bench outside all winter hinges primarily on two key factors: the material it's made from and the severity of your local winter climate.
Let's break it down by material. Modern all-weather materials like powder-coated aluminum, stainless steel, and high-quality synthetic resins (e.g., polywood) are champions of winter endurance. They are designed to resist rust, cracking, and moisture damage. For these, you can typically leave them outside with minimal fuss. However, a quick clean and perhaps a protective cover can keep them looking pristine.
Traditional materials require more attention. Solid teak and other dense hardwoods fare well due to natural oils, but they will gracefully weather to a silvery-gray patina. If you wish to maintain their original color, storing them is best. For benches made of untreated wood, iron, or wicker, winter storage is highly recommended. Moisture from snow and rain, combined with freeze-thaw cycles, can cause untreated wood to rot, iron to rust, and wicker to become brittle and break.
If you decide to leave a sturdy bench outside, proper preparation is key. Give it a thorough cleaning to remove dirt and debris. Apply a fresh coat of sealant or protective oil suitable for its material. Using a high-quality, breathable waterproof cover is highly advisable. Ensure the cover is secured to prevent wind from whipping it around and causing abrasion. If possible, move the bench to a more sheltered spot, like under a deep eaves or against a protected wall.
For storage, choose a dry, cool place like a garage, shed, or basement. Avoid plastic wraps directly on the furniture in damp spaces, as this can trap moisture and promote mold. Instead, use a cotton sheet for dust protection.
In summary, assess your bench's build and your winter's wrath. High-end all-weather materials can brave the storm with some simple protective steps. For more vulnerable materials, the safe bet is a cozy spot indoors. A little effort this fall ensures your favorite bench is ready and welcoming for many springs to come.