Ah, that's an excellent question and one every wooden bench owner should ask! The honest answer is: it depends. There's no universal timeline, but a good rule of thumb is to inspect and likely reapply a fresh coat of stain or sealer every 1 to 3 years. Think of it less as a strict calendar event and more as an ongoing relationship with your bench.
Several key factors will dictate your specific schedule. First, consider your local climate. Benches in harsh, sunny, or rainy climates face more wear and need more frequent care—perhaps every year. In milder, sheltered spots, you might stretch to every 2-3 years. Second, the wood type matters. Dense, oily woods like teak or cedar are more resilient, while porous woods like pine require more vigilant protection.
The product you use is crucial. Clear sealants and transparent stains offer less UV protection and may need annual renewal. Heavier, pigment-rich semi-transparent or solid-color stains provide more defense and can last longer. Always follow the manufacturer's recommendations on the can.
The best approach is the "water test." Once a year, sprinkle water on the bench's surface. If it beads up, your protection is still working. If the water soaks in darkening the wood, it's time for a new coat. Proper preparation—cleaning, sanding, and ensuring the wood is bone-dry before application—is just as important as the frequency itself. Consistent, mindful maintenance will keep your bench beautiful and functional for decades.