Short answer: most wooden outdoor benches do best with a fresh coat of sealer or oil about once a year. If your bench sits in full sun, rain, or snow, or it’s made from pine or another softwood, plan on every 6–12 months. If it’s a naturally oily hardwood like teak or ipe, or it lives under a covered porch, every 18–24 months can be enough.
The quickest way to tell is the water test. Sprinkle a few drops of water on the wood. If the water beads up, the finish is still protecting the surface. If it soaks in and darkens the wood within a few minutes, that’s your cue to treat it again.
The product you choose changes the schedule, too. Penetrating oils like teak oil, tung oil, or linseed oil wear faster and often need reapplication every 3–6 months in exposed spots. Film-forming sealers such as spar urethane or marine varnish usually last 1–2 years, but they can peel. A stain-and-sealer combo typically gives you 1–3 years and adds color while protecting the grain.
For a simple maintenance routine, clean the bench with mild soap and water or a dedicated wood cleaner, let it dry completely, lightly sand any rough areas, then apply a thin, even coat. If you’re using oil, wipe off the excess after 20–30 minutes so it doesn’t become sticky. Try to do this on a dry, mild day—spring or early autumn is perfect.
If you want less upkeep, choose cedar, teak, or white oak and treat them about once a year. Pine and similar softwoods need more frequent care unless you’re happy with a weathered gray look.