Barriers of the Gopher to plants – fences, trenches
As we noted earlier, barriers are a possible strategy, but do not lend themselves to being very practical in a suburban home landscape. You can stop gophers at your borders by digging a trench 18 inches wide and 2 feet deep to intercept the tunneling animals. The sides of the trench should be steep. At suitable intervals, dig a hole in the bottom of the trench and insert a 5-gallon can into the hole to serve as a pit trap. Sooner or later a gopher will blunder into the open trench and fall into one of the cans. Somehow it seems fitting that the trench remedy was first written up in 1917--during World War One.
A barrier screen is effective, but it is not easy to install and it is not pretty. For a barrier to work you must surround the vulnerable plantings with a fence of galvanized wire mesh above and below the ground. Extend the barrier about 2 feet below ground and 10 to 12 inches above. In lighter soils, it is desirable to sink a barrier deeper than 24 inches.
This will provide a measure of protection against gophers. Line the inside of boxed raised beds with hardware cloth or aviary cloth, which has ¼ to ½ inch meshes. Bulb beds and individual shrubs or trees can be protected by ½ inch wire mesh if it is laid on the bottom and sides of the planting hole. In any event, make sure you place the wire deep enough to avoid restricting root growth.
Barriers on the plants preventing Gopher contact
Gophers occasionally feed on the bark of certain trees, particularly fruit and nut trees. Protect tree trunks with cylinders of 1/2 inch galvanized hardware cloth sunk 12 inches underground and rising 12 inches above the surface.
Tip: Try giant “plant collars” to protect plants that grow from clumps and crowns, such as many vegetables, strawberries, and such. For this variant on container gardening, take plastic 5-gallon cans, cut out the bottoms, punch out holes in the sides for extra drainage, and sink them to the rims in holes in your garden. Fill with soil and plant as you normally would. Water them individually or with a soaker hose system.