How to Keep Groundhogs From Digging Under a Fence

Groundhogs do not test a fence by jumping it. They sit at the base and dig, and a fence buried straight down just tells them how deep to go. The shape that stops them is an L.

Why straight-down burial fails

A groundhog’s digging method is to work at the point of resistance. Put a barrier in its way and it follows the barrier down, because that is the direction the obstruction leads. Twelve inches of vertical mesh therefore produces a twelve-inch hole and then a groundhog on your side.

An L-footer breaks that logic. The animal digs at the fence, meets horizontal mesh underfoot, and has no cue telling it to back off a foot and start again.

The spec

The footer sits shallow deliberately — just under the grass line. It does not need depth; it needs width in the direction the animal approaches from.

Installing the footer

1. Cut a shallow trench along the fence line, 10–12 in deep and 12–18 in wide on the outside
2. Unroll the mesh so the lower portion lies flat along the bottom of the trench, pointing away from the garden
3. Stand the rest up against the posts and fix it
4. Peg the horizontal section with landscape staples every couple of feet
5. Backfill with the soil you removed, plus rubble where you expect pressure
6. Replace the turf over the top

Where digging a trench is impractical — tree roots, paving, an existing fence — an alternative is to lay the mesh flat on the surface outside the fence, peg it down hard, and let the grass grow through it. Less tidy, nearly as effective.

The climbing side

Groundhogs climb better than they look, and chain link gives them a ladder.

• Leave the top 12–18 inches of mesh unattached to the posts. It bends outward under their weight and they drop off
• Or fit an outward angled top section at about 45 degrees
• Avoid chain link as the only barrier where groundhogs are the problem
• Keep anything climbable — woodpiles, compost bins, wheelbarrows — away from the fence line

The electric option

A single hot wire, 4 to 6 inches above the ground and 4 to 6 inches outside the fence, catches the animal on the nose exactly where it starts investigating.

• Cheaper and faster than trenching a long perimeter
• Needs the strip beneath kept mown or sprayed — grass touching the wire grounds it out
• Check local rules and keep it clearly signed where people pass
• Works well as a retrofit to a fence that already failed

Dealing with the existing burrow

1. Confirm it is empty. Stuff the entrance loosely with crumpled newspaper and check for two or three days; if it is pushed out, something is living there
2. Avoid roughly April to July, when young may be in the chamber
3. Find the other entrances. A groundhog burrow usually has two to five, including well-hidden spares
4. Fill with rubble then soil, tamped, once it is confirmed clear
5. Install the L-footer over the top, or the same route gets re-excavated

Filling a hole without changing the fence is a task you will repeat.

What does not work

• Mothballs and naphthalene — a pesticide, illegal used this way in many places, toxic
• Ultrasonic devices — no reliable evidence
• Smoke or flooding a burrow — cruel, often illegal, and it can undermine the structures the tunnel runs beneath
• Repellents alone — a few days of effect, then rain
• Trapping as the whole plan — a good burrow site and a vegetable garden will attract the next groundhog within a season