Rodent-proofing a raised bed

An open bottomed raised bed drains well because it sits directly on soil, but that same open bottom gives burrowing animals, including voles, gophers, and similar rodents, a way into the bed from underneath. A hardware cloth liner across the bottom blocks that route without blocking drainage, and it is one of the build variants included with every plan in the Raised Bed Build Pack.

Do you actually need one

Not every location has a burrowing rodent problem, and adding a liner is extra material and labor for a build. If you have seen tunneling, mounds, or damaged roots in nearby garden beds or lawn areas, a liner is a reasonable precaution to add from the start, since retrofitting one under an already filled bed means emptying it first. If there is no evidence of the problem in the area, it is a reasonable step to skip on a first bed and add later if needed.

Choosing the mesh

Half inch or quarter inch galvanized hardware cloth is the standard choice for this purpose. Chicken wire, despite sometimes being suggested for the same job, has openings too large to reliably stop most digging rodents and is not a substitute. Galvanized coating resists rust in the damp, soil contact environment under a bed far longer than uncoated wire mesh would.

Installing it during the build

The liner goes in before the bed is filled, not after. Cut a piece of hardware cloth a few inches larger than the bed's footprint on each side, lay it across the bottom of the assembled frame, and fold the extra few inches up the inside of the walls. Staple the folded edge to the inside face of the bottom board course, so the first layer of soil holds the mesh flat against the ground rather than letting it sag in the middle.

Overlapping seams on larger beds

For a bed too wide for a single roll of hardware cloth to span, overlap two pieces by at least 2 inches along the seam rather than butting them edge to edge, since a rodent will exploit any gap it can find along a seam that does not overlap.

Does it affect drainage

No. Hardware cloth is an open mesh, not a solid barrier, so water passes through it the same way it would through open soil. The mesh only stops something large enough to be blocked by a half inch or quarter inch opening, which is exactly the size range of the rodents it is meant to exclude.

What it does not stop

A bottom liner addresses rodents burrowing up from underneath; it does nothing against animals that can climb or jump into an open topped bed, such as rabbits or deer, which need a different solution such as fencing or a cover. It also is not aimed at insects or smaller pests, which pass through the mesh easily.

Combining with other variants

A hardware cloth bottom is commonly paired with a landscape fabric liner along the interior walls, which serves a different purpose, slowing direct wood and soil contact rather than excluding animals; the two variants do not interfere with each other and can be installed together in the same build. Both are covered as build variants for each of the six plans in the Raised Bed Build Pack, alongside hoop support installation for a season extending cover.

Hardware Cloth Bottom Liner Specs

Use this quick reference when adding a rodent-blocking mesh bottom to an open raised bed.

Detail	Use	Number
Standard mesh	Hardware cloth	1/2 in
Finer mesh	Hardware cloth	1/4 in
Chicken wire	Skip it	Too large
Edge turn-up	Inside walls	Few inches
Seam overlap	Minimum	2 in
Install time	Before soil	Before fill
Fasten point	Bottom board	Inside face

Cut the mesh larger than the bed footprint, fold it up the inside walls, and overlap any seams by at least 2 inches.