Petunias (Petunia spp. and Petunia x hybrida) are simple-to-grow, colorful additions to a flowerbed. They're also favorites on the menu of several kinds of animals, with rabbits and deer topping the list of unwanted diners. One insect in particular is infamous for its attraction to petunias. Petunia plants are tender perennials, with hybrid varieties hardy in U.S. Department of Agriculture plant hardiness zones 9 through 10.
If your new petunias disappear overnight, the first among the usual suspects should be the rabbit. Rabbits apparently think of petunias as a salad ingredient. You have six options of varying degrees of effectiveness to keep rabbits from your petunias:
most effective method is to block rabbits from petunias by using a chicken wire fence with 1-inch-diameter or smaller holes. The fence
should be least 2 feet high and buried at least 3 inches deep.
patches of weeds, piles of brush and stones or other debris that rabbits might
use to hide. This is especially effective in cities and suburban areas.
- Pour a thin
line of blood meal in a perimeter around your petunias.
- Use a kitchen flower sifter to
sprinkle chili powder, cayenne pepper, ground black pepper, raw ground
limestone, talcum powder or wood ashes on your petunias when they are wet.
- Get a yard dog or cat.
- Plant your petunias in tall planters, window boxes or hanging baskets to
put them out of rabbits' reach.
Whether they're white-tailed deer in the U.S. East or mule deer in the West, deer browse on flowers, including petunia blooms.
You can string a barrier of black polynetting around your petunias. It may be less visually less distracting than a wire fence.
For a simple repellent that La Planta County, Colorado, calls "Not Tonite, Deer," blend one raw egg in 2 quarts of water. Spray the mixture on the leaves of your petunias. With time, the petunias will have the odor of rotten eggs to deer, which will leave the plants alone. Humans detect the odor for only several minutes after the spray is applied. Repeat the application every several days or after it rains.
A more complicated but more potent variation requires blending one egg, 1 tablespoon of lemon-scented dish-washing soap, 1 tablespoon of cooking oil and two dashes of hot sauce with 1/2 cup of whole milk. Combine those ingredients with 1 gallon of water, and spray the mixture on petunia leaves once every 10 to 12 days.
An insect called the tobacco budworm can be devastating to petunias. Studies conducted by entomologists at the University of California found that Bacillus thuringiensis, or Bt, a biological control agent, is effective in controlling tobacco budworm. That creature's attraction to petunias has made the plants less popular than they previously were for home gardeners.
The caterpillar, or larva, of the tobacco budworm moth, found mainly in the U.S. Southwest and East, bores into buds and blossoms, hence its name. It also eats and leaves and stems.
Yellow or greenish-yellow with a lateral brownish stripe on both sides of its body, a tobacco budworm caterpillar grows up to 2 inches long and has a toothlike projection on its jaws. The caterpillar emerges and begins eating plants in spring, maturing into into a brownish moth tinged with green. The moth's front wings are crossed with three dark bands that have cream-colored or white edges.
Bt is derived from a naturally occurring bacterium found in soil and in the guts of moths and butterflies. It is approved for organic gardening.
Ready-to-use Bt sprays are sold in aerosol cans at many garden-supply centers and plant nurseries. Tobacco budworm caterpillars have to eat Bt for it to work. Spray the caterpillars, not the moths, with Bt. Spray Bt when you first see them on your petunias. Shake a can of the spray before using it, and then spray both the tops and bottoms of infested leaves. Repeat the application once every five to seven days until they're gone.
Foraging chickens have many benefits in a flower garden. They eat insects. Their manure enriches the soil. They also peck at petunias.
There is a reason for the term "chicken wire." Chicken wire fences are used to keep foxes out of and chickens in the fenced areas. If you have free-range chickens, then blocking them out with chicken wire is about all you can do to protect your petunias. You can encircle your petunias with chicken wire or build a chicken wire fence.
A fence that is 24 inches high may block rabbits, but not chickens. Chickens have wings, and the fence needs to be at least 40 inches high.
Mice and Squirrels
Although they are not on the top of the list of usual petunia-eating suspects, mice and squirrels may find petunias attractive.
Mice and squirrels hate castor oil. To deter them, mix 1 tablespoon of liquid soap and 1 tablespoon of caster with 1 gallon of water, and pour the solution over the soil around your petunias. Rain may wash the solution away, forcing you to reapply it.