Preserving Raised Bed Wood: Skip the Coatings, Use Thick Untreated Timber

What to Put on the Outside of a Raised Bed Frame?

You want to coat the exterior of your raised garden frame to prevent rot, but it must be safe for edibles.

Don’t Use Paint, Stain, or Sealers

Any coating can leach chemicals into the soil over time—especially with constant moisture contact. Even “non-toxic” labels don’t guarantee long-term safety for root uptake.

The Simple, Safe Solution

Build the frame from 4×4 or 6×6 untreated landscape timbers (or rough-cut cedar, locust, or oak if available). Thick, solid wood lasts 10–20 years without treatment. It’s cheap, structural, and completely inert.

If You Must Use Thinner Boards

• Line the inside with heavy-duty landscape fabric (stapled) to separate soil from wood.
• Use naturally rot-resistant species: cedar, redwood, black locust, cypress.
• Accept that they’ll need replacement sooner—but your food stays clean.

Thick untreated timber is the only truly worry-free choice for edible gardens.