Gopher- and Vole-Proofing an 8-by-10 Backyard Greenhouse Floor with 1/4-Inch Hardware Cloth, Landscape Fabric, and 6-Inch Landscape Staples

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Before the greenhouse base goes down, cover the whole leveled footprint with 1/4-inch, 23-gauge galvanized hardware cloth, run it 12 inches past the base on all sides, and pin it with 6-inch, 11-gauge landscape staples. Lay woven landscape fabric over the mesh, pin both layers together every 12 inches, and finish with 3 inches of pea gravel. The staples lock mesh and fabric into one flat floor, so no edge lifts and no gopher or vole comes up under the benches.

What keeps gophers and voles from tunneling up through a greenhouse floor?

A continuous floor of 1/4-inch, 23-gauge galvanized hardware cloth under the whole footprint, run 12 inches past the base as an apron and pinned with 6-inch landscape staples every 12 inches on seams and edges. Voles need the 1/4-inch opening; 1/2-inch mesh only stops gophers.

The Montana Department of Agriculture's pocket gopher control techniques says barriers that block gophers from sensitive areas are practical only for small plots or high-value crops. It specifies 1/4-inch wire mesh, notes that galvanized mesh holds up better to weathering, and says to protect vegetable gardens by placing 1/4-inch hardware cloth below the roots in the shape of a house foundation.

An 8 × 10 greenhouse full of seedlings is exactly that kind of small, high-value plot. A single gopher tunnel under the floor can empty a bench of transplants overnight.

Penn State Extension's vole fact sheet says 1/4-inch hardware cloth guards help prevent meadow vole damage and should be buried 4 to 6 inches to keep voles from burrowing under. 1/2-inch mesh is fine for gophers, but voles need the 1/4-inch opening, as the hardware cloth mesh size and gauge guide shows.

Floor Layer Stack

Layer (bottom to top) Spec Job
Native soil Leveled, tamped, 2 inches below finished floor Firm base so mesh lies flat
Hardware cloth 1/4-inch, 23-gauge galvanized, seams lapped 6 inches Gopher and vole barrier
Landscape staples 6-inch, 11-gauge, every 12 inches on seams, edges, and the apron Locks mesh and fabric to the soil
Landscape fabric Woven polypropylene, seams lapped 12 inches Weed barrier; keeps gravel out of the mesh
Pea gravel 3 inches, raked level Drainage and a clean floor
Base frame Pressure-treated 4x4 or kit base, set on the mesh Holds the greenhouse frame

Staple Plan for an 8 × 10 Floor

Area Size Spacing Approximate staples
Mesh field, including apron 10 × 12 ft 24-inch grid About 42
Mesh seams (two laps) 2 × 12 ft Every 12 inches About 26
Outside apron edge 44 ft around the base Every 12 inches About 44
Fabric over the apron 44 ft Every 12 inches, offset 6 inches from the mesh staples About 44
Door threshold 3 ft Every 6 inches About 7

Plan on about 165 staples for an 8 × 10, and buy extra for loose soil.

Materials and Tools

  • 6-inch, 11-gauge galvanized landscape staples, about 165 for an 8 × 10 floor
  • 1/4-inch, 23-gauge galvanized hardware cloth, three 48-inch × 12-ft pieces (covers 11 × 12 ft with two 6-inch seam laps)
  • Woven landscape fabric, 10 × 12 ft or two lapped pieces
  • About 1 cubic yard of pea gravel
  • Straight-cut aviation snips and lineman's pliers
  • 2-lb drilling hammer or rubber mallet
  • Flat spade, steel rake, hand tamper, and a 4-ft level
  • Leather gloves, safety glasses, and long sleeves

Installation Sequence

  1. Lay out the footprint. Mark the greenhouse base plus 12 inches on every side, so an 8 × 10 becomes a 10 × 12 ft work area.
  2. Strip and level. Remove sod and roots, dig the floor 2 inches below finished grade, then level and tamp the whole area.
  3. Roll out the mesh. Lay the first 48-inch strip along one long side, pin its outer edge every 12 inches, and pin a 24-inch grid across it.
  4. Lap the seams. Lay the second and third strips 6 inches over the one before and pin through both layers every 12 inches, then trim the excess to the 10 × 12 ft line. Staples replace the ties here, but the lap logic is the same as when overlapping hardware cloth seams above ground.
  5. Pin the apron. Pull the outer 12 inches of mesh flat beyond the base line and pin its edge every 12 inches, the same wing idea Montana uses to stop gophers digging under a barrier.
  6. Set the base. Set the greenhouse base frame on the mesh, level it, and anchor it per the kit; the mesh runs continuously under the timbers.
  7. Lay the fabric. Spread landscape fabric over the floor and apron, lap seams 12 inches, and pin it every 12 inches, offset from the mesh staples so each staple catches new wire.
  8. Seal the threshold. Add a staple every 6 inches across the door opening and set a 2x4 sill or paver strip over it.
  9. Gravel the floor. Spread 3 inches of pea gravel inside and at least 2 inches over the outside apron, then rake level.

For any in-ground bed inside the greenhouse, line it as a basket the way you would when you line raised garden beds with hardware cloth, and lap that liner 6 inches onto the floor mesh.

Keep the Outside Unattractive

Penn State says eliminating weeds, ground cover, and litter is an excellent long-term way to control voles, and mowing to keep ground cover at 3 to 6 inches reduces food and cover. It also lists a 3 to 4 inch layer of crushed stone or gravel as one way to make a vegetation-free zone.

The gravel-topped apron does that job around the greenhouse. Keep it weeded, and don't stack pots, flats, or bagged mix against the outside walls.

Common Greenhouse Floor Mistakes

  • Using 1/2-inch mesh where voles are the problem; the same rule drives the floor of a cold frame with hinged vent screens
  • Stopping the mesh at the inside face of the base, leaving a gap under the timbers
  • Skipping the outside apron
  • Pinning the fabric but not the mesh underneath
  • Butting mesh seams instead of lapping them 6 inches
  • Leaving the door threshold unpinned
  • Piling bags and flats against the outside walls

FAQ

Can I add mesh to a greenhouse that's already built?

Yes, but only on the inside floor and an outside apron. Pin a 12-inch apron outside and fasten the inside mesh to the base timbers with 1-inch fender washers and screws every 6 inches.

Do I need landscape fabric if I have hardware cloth?

The fabric is the weed barrier, and the hardware cloth is the rodent barrier. Fabric alone won't stop a gopher or a vole.

Will the staples rust out?

Galvanized staples last much longer than bare steel. Montana notes that galvanized mesh holds up better to weathering, so use galvanized for both.

How long should the mesh last under gravel?

Inspect the apron edge every spring. Replace any section where the wire has rusted through or a staple has heaved.

Quick Greenhouse Floor Checklist

  • Footprint plus 12 inches stripped, leveled, and tamped 2 inches below grade
  • 1/4-inch, 23-gauge galvanized hardware cloth, seams lapped 6 inches
  • 6-inch, 11-gauge staples on a 24-inch grid and every 12 inches on seams and apron edges
  • Mesh continuous under the base timbers, with a pinned 12-inch outside apron
  • Woven landscape fabric lapped 12 inches, pinned offset from the mesh staples
  • Door threshold stapled every 6 inches and sealed with a sill
  • 3 inches of pea gravel inside, 2 inches over the apron
  • Apron kept weeded and clear of stored materials

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