The Knock Out rose (Rosa "Radrazz") took garden centers and nurseries by storm when it was introduced in 2000. This hardy, compact shrub rose, which grows in U.S. Department of Agriculture plant hardiness zones 5 through 11, promised disease resistance rarely seen in commercially produced roses, making it an instant favorite with home gardeners dismayed by continuously applying fungicides to their prized rose gardens. Although this shrub rose and the other members of the Knock Out family show good disease resistance, several critters and insect pests still favor the tender flowers, canes and rosebuds.
A few species of deer, particularly the whitetail deer, thoroughly enjoy grazing rose gardens. While deer can and may eat a whole bush -- thorns and all, big, fat rose buds really get their mouths watering.
Gophers, which live most of their lives underground, devastate rose gardens and shrubs by eating the tender roots and digging tunnels that disturb the root system.
Tender shoots and buds may also fall victim to other mammals, such as squirrels.
Keeping pests out is the only surefire way to keep your roses safe, but it's not always the most feasible or affordable option. An 8-foot fence around your rose garden will keep agile deer out, but may block the beauty of your Knock Out rose bushes from the outside world. Placing a fence around your entire property may help the aesthetics of your rose garden but, again, is a costly endeavor.
Gopher cages help keep gophers from eating the tender roots of your prized Knock Out roses, but are meant to go in the ground at planting time. These wire cages, available in several sizes, are constructed of strong, gopher-proof wire. For a large rose garden, an underground fence or barrier around the perimeter may do the trick.
You'll need 36-inch-tall galvanized hardware cloth with a maximum of 1/2-inch openings or mesh that is long enough to go around your garden. Dig a trench 2-feet deep and 6-inches wide around your rose garden. Bend the bottom 6 inches of the fencing out to a 90-degree angle and place this part in the bottom of the trench; gophers can dig deeper than 24 inches, but the 6-inch shelf will help keep them at bay. Refill the trench with soil and pack it tightly. Another option is filling a 10-inch wide by 24-inch deep trench with large gravel.
Above-ground pests, such as deer and squirrels, may start to leave your roses alone after experiencing a bad taste. Several commercial repellents line the shelves of hardware and garden stores, and many use natural ingredients such as egg solids, capsaicin and garlic. Some of these might be temporarily effective. You can make your own hot sauce spray, which uses the power of capsaicin. Other homemade options include hanging bars of strong-smelling soap, which may or may not work.
Homemade Spray Recipes
James E. Armstrong of the American Rose Society recommends mixing 1 teaspoon of hot pepper oil and a raw egg in 1 quart of water and spraying it on the roses.
Another recipe calls for adding one chopped yellow onion, one chopped jalapeno and 1 tablespoon of cayenne pepper to 2 quarts of water. Boil this mix for 20 minutes, let it cool and then strain it through cheesecloth before putting in a spray bottle.
You'll have to spray your roses about twice per week until the critters get the message, and every time after it rains or you have a foggy, humid day. Capsaicin burns the mouth and skin -- it's the chemical in hot peppers that give them their heat -- so a few tastes of this mixture should leave a bad taste in pests' mouths.