Wood decks need a wash and a fresh coat of stain or sealer every two to four years depending on sun exposure. Composite and PVC decks are never stained, but they still need regular cleaning to prevent mold and mildew buildup, which is a different job entirely.
Stain and sealer are not the same product doing the same job. Stain adds color and penetrates the wood grain. A sealer sheds water and slows the cracking, cupping and graying that comes from sun and Ohio freeze and thaw cycles. Most finish products combine both jobs in one coat, but the two functions are worth knowing apart when you are comparing products.
A deck in full sun needs restaining more often than a shaded one, typically every two to four years rather than on a fixed calendar. A new deck should not be stained immediately: fresh treated lumber needs time to dry out first, or the finish will not take properly.
Painting is a different approach entirely: a solid color that fully covers the wood grain instead of penetrating it. It hides the wood rather than protecting its look. We focus on staining and sealing, which preserves the grain, not painting.
A wash is the first step before any finish goes on, and the finish only holds as long as the surface underneath is clean. Dirt, mildew and old finish residue all keep a new coat from bonding properly, so skipping this step is the most common reason a fresh stain job fails early.
Composite and PVC decks get washed too, even though they are never stained. Regular cleaning is what actually keeps them looking new, not a one-time treatment.
Composite and PVC boards do not get stained or sealed. That does not mean they need no attention. Mold and mildew build up on any decking surface, composite included, and left alone it stains the surface in a way that a wash after the fact does not fully reverse. Regular washing on a schedule prevents the buildup instead of trying to remove it later.
Manufacturer pages for composite and PVC products tend to undersell how much care actually helps, since low maintenance is part of how those materials are marketed. Low maintenance is not no maintenance.
General maintenance guidance drawn from how wood, composite and PVC decking products actually perform outdoors in Ohio's freeze and thaw climate, not manufacturer marketing copy. Sources: Ohio Administrative Code, Chapter 4101:8-5.