What do you put on the bottom of a raised garden bed?

Line the bottom of a raised garden bed with cardboard or hardware cloth — cardboard suppresses weeds and breaks down into organic matter, while hardware cloth blocks burrowing pests like gophers and voles.

The right bottom liner depends on your specific ground conditions. On grass or weed-heavy soil, a single layer of overlapping cardboard (at least 4 sheets thick at seams) smothers existing vegetation without chemicals and decomposes within one season. On sandy or loose soil where drainage is already good, cardboard alone is sufficient. In areas with active rodent pressure — common in Midwest and Western gardens — a layer of 1/4-inch galvanized hardware cloth stapled or bent up the sides adds meaningful protection that cardboard cannot provide.

• Cardboard liner thickness: minimum 4 overlapping sheets at seams to block light and suppress weeds reliably.
• Hardware cloth gauge for pest exclusion: 1/4-inch galvanized mesh — larger openings allow small rodents through.
• Cardboard decomposition timeline: fully broken down within one growing season, improving soil structure.
• Specraft raised garden beds use an open-base drainage design, so bottom liners rest on native ground without impeding water flow.
• Recommended soil depth for most vegetables including tomatoes and root crops: minimum 12–15 inches above the liner.