Plant Problem Diagnostic
Should You Line the Bottom of a Raised Bed?
The short answer
Whether to line a raised bed depends entirely on the goal, and the material determines whether it helps or hurts. Solid plastic sheeting at the bottom is generally a no: it blocks drainage, traps water around the roots, and prevents roots from reaching the soil below, all of which can drown or stunt plants. If you want to line for any reason, it should never be with an impermeable material at the base.
Landscape fabric is a maybe, useful under the bed to slow weeds and grass creeping up from below, though it can eventually clog or restrict deep roots. The strongest case for a liner is animal protection: a bottom layer of galvanized hardware cloth (metal mesh) is the reliable way to stop burrowing gophers, voles, and moles because it physically blocks them while letting water and roots pass freely. That is a regional call: line for gophers where you actually have gophers.
Plastic: don't
A solid plastic liner across the bottom of a raised bed defeats one of the main advantages of a raised bed, which is good drainage. Water that can't drain pools at the base and leads to root rot, and roots that can't grow downward stay shallow and stressed. Plastic and other impermeable fabrics restrict water flow, so they are the wrong choice for the base. If you want to protect wooden sides from soil moisture, line the interior walls only, never the bottom, and leave the base open to the ground.
Fabric: maybe, for weeds
Permeable landscape fabric or even a few layers of plain cardboard at the bottom can suppress grass and perennial weeds trying to grow up into a new bed from the soil beneath, which is a legitimate use, especially on a former lawn. The tradeoffs are that fabric can clog over time and may impede the deepest roots, and cardboard breaks down within a season (which is often fine, since the weeds are smothered by then). Fabric will not stop a determined burrowing rodent, so it solves weeds, not gophers.
Hardware cloth: yes, for burrowing pests
In gopher, vole, and mole country, a metal barrier is the durable fix. Line the bottom of the bed with galvanized hardware cloth before adding soil, running it a short way up the inside walls so animals can't tunnel in at the frame line. Half-inch mesh is a common recommendation for gophers and voles; because it's metal it lasts for years, and because it's an open mesh it lets water drain and roots grow through freely, unlike plastic or fabric. This is a regional decision: install it where burrowing pests are a known problem, and skip it where they aren't.
✔ Use galvanized (not plain steel) hardware cloth so it resists rust, and staple it securely to the frame so gophers can't push through gaps at the edges.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- University of California ANR / Master Gardeners - Vertebrate Pests: Pocket Gophers — Lining the bottom of raised beds and planting holes with galvanized wire mesh (hardware cloth) excludes burrowing pocket gophers while allowing roots and water to pass; mesh openings should be small enough to block the animals.
- Oregon State University Extension - Raised Bed Construction and Materials — Raised beds should drain freely; impermeable plastic liners on the bottom trap water and impede roots, whereas permeable materials or open bottoms preserve drainage.