Keeping Pests From Raised Beds

One of the advantages of raised-bed gardens is that they make it easier to protect your flowers and vegetables from pests, including those that come from above, below or within. It's best to include pest-proofing when you build your beds, but you can add it later, if necessary. Doing so eliminates the need to resort to lethal control practices, such as trapping and poisoning, that can have unwanted consequences.

The frame of a raised bed prevents gophers, moles and voles from wandering into your garden from the surface, especially if it has an overhanging top rail. To prevent them from burrowing in, cover the bottom with galvanized gopher wire. Openings that are 1/2 by 1 inch or 3/4 inches square are recommended. Gophers can still attack roots that extend through the mesh, however, so it pays to exclude them from the yard completely by surrounding the planting area with a mesh barrier made of the same material. This barrier should extend 24 inches into the ground and should have a 6-inch section that extends horizontally away from the garden to prevent animals from burrowing under it.

Because they eat insects that can damage your plants, birds can be beneficial, but when you're planting or ready to harvest, they can cause frustration by pilfering seeds or your ready-to-harvest strawberries. Crows present a particularly pernicious problem. They are smart and persistent. Strategies for deterring birds -- including crows -- include:

Constructing a frame around each bed and covering it with netting. Bending PVC pipe into arches and attaching them to the insides of the frame with pipe straps is an easy way to make the frame, and you can connect the netting to the pipes with twist ties so you can move it when you need to work. 

Stretching thin black wire between the posts of the bed frame. The wires confuse birds, and they'll stay away from them -- and your garden.

Protecting individual plants with crates, disposable cups or other appropriate barriers until they have grown large enough to no longer be vulnerable to birds. 

Scaring birds with shiny objects or wavy ribbons that blow in the breeze. If crows are around, it's best to move the objects around every few days, because the birds quickly lose their fear of anything that stays in the same place.

Rats and mice that can climb over the sides of your beds are likely to be undeterred by any bird-exclusion strategies; they may be able to chew through the netting or slip underneath it. They are often in search of water, and placing a bowl of water near each bed may prevent them from chewing stalks in search of moisture. When that doesn't work, set live traps throughout the garden and bait them with peanut butter or cheese. Check the traps frequently and take the animals you catch at least a mile away -- if you release them any closer, they'll probably find their way back.

Insects are a fact of life, but those that don't get eaten by birds can do extensive damage to your garden, especially their larvae. To avoid the need for toxic insecticides, include flowers that repel insects, worms and larvae in your planting. Examples include:

Borage or Starflower (Ipheion uniflorum), hardy in USDA zones 5 through 11. This plant repels hornworms and cabbage worms.

Mexican Marigold (Tagetes lucida), hardy in zones 8 through 11. Mexican marigolds have a pungent aroma that repels many types of insects. Contrary to folk wisdom, they don't repel rabbits. 

Nasturtium (Tropaeolum majus), hardy in zones 1 through 10. Nasturtiums can repel aphids, squash beetles, whiteflies and cucumber beetles.

Petunia (Petunia), hardy in zones 9 through 11. Petunias also repel aphids, as well as asparagus beetles, tomato hornworms and leafhoppers.