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.

Tools, quantities, and working dimensions

Measure the outside length and outside width of the assembled bed, then add 6 inches to each dimension so the mesh can turn up 3 inches on all four inside faces. For a 4 ft by 8 ft bed, that means cutting a piece about 4 ft 6 in by 8 ft 6 in if the roll width allows it. If the roll is narrower than the bed, plan the seam before cutting, so the overlap lands flat and is not forced into a corner.

Item	Practical figure to use	Why it matters
Side upturn	3 in minimum	Gives enough mesh to fasten to the lower board and keeps soil pressure from pulling the edge inward.
Seam overlap	2 in minimum, 4 in preferred where soil is loose	Prevents a straight gap from opening when the mesh is walked on or filled over.
Staple spacing	Every 3 to 4 in along edges	Holds the folded mesh tight until the bed is filled.
Cutting allowance	6 in added to length and width	Allows a 3 in fold on each side without stretching the mesh.
Extra time	20 to 45 minutes for one bed	Most of the time is spent trimming, folding, and fastening safely.

Use tin snips or aviation snips for cutting, heavy gloves for handling the cut wire, a tape measure, a marker, a straight board for creasing folds, and a hand stapler or pneumatic stapler suitable for outdoor framing work. Eye protection is useful because cut wire ends can spring back while trimming.

Step by step installation procedure

Set the empty frame on a flat surface close to its final position. Square the frame first, because the hardware cloth will hold the shape once it is fastened. Measure both diagonals of the bed, and adjust the frame until the two measurements are within about 1/2 in on a typical 4 ft by 8 ft bed.

Roll the hardware cloth out on the ground and weight the corners with boards or bricks so it stops curling while you measure.
Mark the cut size from the outside bed dimensions plus 6 inches in both directions.
Cut slowly along one wire line, keeping hands away from the fresh edge.
Place the mesh under or inside the empty frame, depending on your build sequence, and center it so the same amount reaches each side.
Press the mesh into the inside corners with a scrap board, then fold the surplus upward against the inner wall.
Fasten the fold every 3 to 4 inches, adding an extra staple within 1 inch of each corner.
At corners, make one vertical relief cut only as high as the fold, then overlap the two flaps rather than leaving an open V shaped gap.
Add 2 to 3 inches of coarse compost, soil, or native mineral soil first, and spread it by hand or with a rake before dumping heavier loads.

If two mesh pieces are used, place the overlap so the upper piece faces the direction from which soil will be pushed during filling. Tie the seam with short pieces of galvanized wire every 8 to 12 inches if the mesh lifts or curls. This is slower than stapling only the sides, but it keeps the seam flat while the first soil layer is added.

Common mistakes and recovery fixes

If the mesh was cut flush with the inside of the bed, do not rely on soil weight alone to hold it. Cut 4 inch wide strips of hardware cloth, overlap them 2 inches onto the flat bottom mesh, turn the remaining width up the wall, and staple the strips to create a continuous edge. Wire the strip to the bottom mesh every 8 inches where access allows.

If a seam was butted edge to edge, empty only the soil needed to expose a 6 to 8 inch band along the seam. Lay a new strip of hardware cloth centered over the joint, with at least 3 inches covering each side, then wire it down at close intervals. This is usually faster than removing the full liner.

If the mesh sags after filling begins, stop before more than 4 inches of soil is in the bed. Pull the soil back, lift the sag by hand, and add more staples along the folded sides. A sagging liner is not usually a drainage problem, but it can create a low pocket that is difficult to correct after the bed is full.

If sharp wire ends are exposed above the soil line, trim them below the top of the bottom board or bend them flat with pliers. Do not leave points where hands will reach during planting, weeding, or harvesting. For more general raised bed questions, see the FAQ.

Special cases to plan before cutting

On rocky or uneven ground, remove stones larger than about 2 inches directly under the bed footprint before placing the liner. A sharp stone under loaded soil can press a permanent high point into the mesh. A thin leveling layer of native soil, about 1 inch deep, is enough to protect the wire without changing drainage in a meaningful way.

For beds set on a slope, fasten the downhill side first, then pull the mesh tight toward the uphill side before stapling. Soil pressure will move downhill during filling, so the seam and folds should not be loose on that side. If the slope is strong enough that the bed needs terracing, solve the support problem before installing the liner.

For very long beds, work in sections of 6 to 8 feet. Fasten and check each section before moving to the next, instead of trying to align a long, springy sheet all at once. For tall beds, the liner still belongs at the bottom, not halfway up the soil depth, because the access route being blocked is from below.

For beds placed over tree roots, do not use the liner as a root barrier. Hardware cloth openings allow fine roots to pass, and larger roots can distort the mesh over time. If tree competition is the main problem, choose a different location or use a separate root control strategy rather than treating rodent mesh as a solid bottom.