Honestly, you'd think there's one magic number, but it really depends on where you live and how much weather that bench actually sees. If your cedar bench is sitting in full, blazing sun all day or getting blasted by rain and snow, you’ll be sealing it more often than one sitting pretty on a covered porch.
As a general rule of thumb, a clear penetrating sealant on a cedar park bench lasts about 1 to 2 years. I usually tell people to plan on doing it every spring, but not blindly. The wood will tell you when it’s thirsty. Drip some water on the surface—if it beads up, your sealant is still doing its job. If the water sinks in and darkens the wood within a couple of seconds, you’re overdue. No need to overthink it.
A lot of folks ask me if they need to strip and sand every time. Nope. If you’re using a good penetrating oil like a linseed or tung oil blend, or even a modern synthetic sealer, a clean surface is usually enough for a maintenance coat. Just give it a light wash with a wood cleaner, let it dry, and brush on the new sealant. The big deep clean and sanding only really needs to happen if you’ve let it go too long and the grain feels rough or you see gray, weathered patches.
One thing I learned the hard way: avoid heavy film-forming varnishes on a park bench unless you love peeling and scraping later. They crack, trap moisture, and turn a simple yearly task into a weekend project. Stick with a clear or lightly tinted penetrating sealant that lets the cedar breathe. It might feel like you’re applying it more often, but the whole job takes less than an hour, and your bench will never look sad and neglected.
So, real-world answer? Check it once a year, probably in spring after the last frost. If the water test fails, seal it. If it’s still beading, give yourself a pat on the back and enjoy a lemonade on that bench instead.