If flowers and plants start falling over in the back yard, it may not be because of bad gardening habits. A vole could be on the loose.
Voles are a major threat to vegetable and ornamental gardens, says Adria Bordas, horticulture extension agent in Fairfax County.
"They feed at the roots and the material at the soil line," Ms. Bordas says. "They will basically eat all the roots, and you will have your plants fall over one day in your yard."
Critters of all shapes and sizes can destroy a garden with little effort. A fuzzy-tailed animal easily could eat a flower garden for lunch, while other animals like to dig holes in the terrain.
For gardeners who are having difficulties with destructive animals, 90 percent of their problems can be solved by installing a fence, says Jim Parkhurst, associate professor in the department of fisheries and wildlife science at Virginia Polytechnic Institute and State University in Blacksburg. He holds a doctorate in wildlife science.
Apart from not installing a fence, the main mistake people make is installing it improperly, he says. The fence needs to be buried 8 to 10 inches into the ground and L-shaped prongs should extend under the ground away from the garden another 6 to 8 inches.
"If you have something like rabbits or groundhogs, that are digging animals, if you put a fence just to the ground surface, they will easily dig under it," Mr. Parkhurst says. "Burying it with a return will allow them to encounter a fence in front of them and below them. If they try a few inches over and have the same problems, they will very often give up."
Appropriate material needs to be used for the fence, he says. Generally, a 1-inch mesh fence is best; baby rabbits and other smaller critters can go through the larger fences.
To drive away climbing animals such as groundhogs, the posts should be on the inside so they aren't used to climb, he says. The fence should wiggle a bit if an animal tries to climb it; the wobbly feeling may deter the critter.
"In the most complex situation, we have to encourage people to put an extension on the top of it, to prevent the most persistent climber," Mr. Parkhurst says. "You can bend the fence outward at the top at a 45 degree angle, that usually will stop just about everything."
With deer, the average fence is not going to do it, he says. To stop deer, the fence has to be about 8 feet tall.
"People will have to make some decisions if they want to go to that extent or if a garden is really important for them," Mr. Parkhurst says. "Even with an 8-foot fence, the deer can get over it with a good running start."
Research shows that repellents are not always effective, he says. When the food supply is restricted, if the animals have to eat they will, even if it smells bad.
"With habituated animals, don't look to repellents to be the end-all," Mr. Parkhurst says. "A fence is a more effective strategy."
The most successful defense usually incorporates many strategies, says David Yost, plant specialist at Merrifield Garden Center in Fairfax. Fencing, traps, poisons and repellents are the four major options to deter wildlife.
Lately, rabbits seem to be a big problem in the area, he says. Bobbex-R rabbit repellent usually lasts six to eight weeks, but can't be sprayed on fruits or vegetables.
"It's made of a concoction of hot pepper, garlic and rotten eggs," Mr. Yost says. "It is nothing poisonous or harmful, but if you spray it on your vegetable garden, your garden will taste horrible."
Of all the critters, voles are usually the most destructive animal, he says. The main way Mr. Yost has found to deter them is through poison. Otherwise, customers might try VoleBloc, a stone material that is placed beneath areas where bulbs are planted to prevent voles from eating them.
"Poison kills voles, but I'm always very cautious with using any poison," Mr. Yost says. "I require people to come in and talk to me about building bait stations, to prevent other wildlife from getting into them."
Unlike voles, in the overall scheme of things, moles are beneficial because they feed on insects and bugs in the soil, he says. Although they cultivate the soil by digging through it, the tunnels they create are unsightly and can cause people to stumble. Good repellents for moles usually are made of castor oil in liquid or granule form.
Squirrels, raccoons and skunks usually are more of a nuisance than a destructive force, he says. For instance, squirrels will make a pest of themselves by eating all the seed in the bird feeder. They will uproot the garden. Repellents such as Repels-ALL and using dried blood as an organic fertilizer tend to deter them.
"They go digging into flower pots and containers," Mr. Yost says. "They turn everything over. They throw the plants and soil out. They don't feed off the plants, like deer and rabbits. They just make a mess of it."
To deter herons, using a plastic heron as a decoy might cause them to be distracted because they are territorial, he says. Raccoons may eat the fish in an ornamental fish pond. Putting a net over the pond is an option. As far as skunks go, there really isn't a suitable solution, so far, he says.
Sometimes, fertilizer and repellent products come together, says Eric Roozen, owner of Roozen Nursery and Garden Center in Fort Washington.
"We use Alaska Fish Fertilizer," Mr. Roozen says. "It feeds the plants and the side effect is that the deer and rabbits stay away. You can use it on the vegetables, flowers and bushes because it's an organic fertilizer."
When someone chooses to spray repellent, it should be done immediately upon planting. Otherwise, nothing will keep the animals away. The plants should be sprayed every week for three weeks and then once a month, interchanging repellents, so the animals don't get used to them, he says.
Another suggestion Mr. Roozen offers: plant daffodils instead of tulips, whenever possible.
"In the springtime, when the tulips come up, the deer will eat them all up," Mr. Roozen says. "It's better to plant daffodils. As soon as the tulips come up, they become a snack. Animals don't bother daffodils. The deer also love pansies."
"With habituated animals, don't look to repellents to be the end-all." — —Jim Parkhurst, associate professor, Virginia Polytechnic Institute and State University department of fisheries and wildlife science