Dr. Leonard Perry, Extension Professor
University of Vermont
Deterrents are easy and inexpensive, and so are usually the first line of defense of gardeners against unwanted deer in their gardens. Of the various methods that surprise or offend their senses from smells, tastes, hearing, or touch, odor repellents are quite popular.
Odor repellents can be placed into two groups. Those that interfere with a deerís sensitive sense of smell, which it uses to sense danger, include the popular aromatic soap bars. Those that send an alert to danger include predator scents.
Some products that are sprayed on may need frequent reapplication, especially after rains. Humid weather, however, may actually enhance the scents. Since deer feed from ground level to about six feet high (thatís six feet above the snow line in winter), this is the area where such repellents should be applied.
In the category of offensive scents is one of the easiest controls -- hanging bars of smelly soap in the garden, the stronger the scent the better. I actually buy them in bulk at the grocer, then cut them in half and hang in burlap or cheesecloth stapled to stakes in the garden in early spring. I find they are still scented going into the winter. If using soap bars, just donít hang them directly on shrubs. The soap will drip down the stems, attracting rodents which eat the soap and the bark too. I have found some soaps may even attract small mammals such as raccoons, only to be dragged off and nibbled!
Studies actually have been done on soaps to repel deer, finding that those containing coconut oils may attract deer. The repellent factor seems to be tallow, that part derived from animal fatty acids. Studies have also found deer can feed to within three feet of soap in the garden. This means a 100-foot border may need over 30 bars of soap! I tend to use less, one about every ten feet or near special plants, and hope for the best. But then I donít have high deer pressure either.
In the category of alert scents is another popular remedy Ė hanging human hair in bags of nylon or cheesecloth. It is easy to find at local hair salons, but losing its scent in a few weeks needs replacement at least monthly. Deer in urban areas, used to humans, may not respond to this repellent.
Repellent plants are those that are highly aromatic, in the offensive scent category for deer. These are often perennial herbs such as artemisia, tansy, and yarrow. Culinary herbs such as mint, thyme, tarragon, oregano, dill, and chives can also be interplanted throughout the garden.
There are many spray-on odor repellents, both commercial products and home remedies. Especially for the latter, you may need to add a surfactant product to help them last and not be easily washed off in rain. Keep in mind many of these products may be offensive to humans as well! Examples include garlic and rotten eggs (ingredients of some commercial products too), ammonia, processed sewage, blood-derived or fish products. One product Iíve heard is effective is derived from slaughterhouse wastes, perhaps not only offending deer but signaling potential danger.
You should beware of acquiring and using raw slaughterhouse wastes (often called tankage) yourself, as it may attract predators, attract yellow jackets in summer, and may be loaded with harmful bacteria. Mothballs also are commonly used in gardens for deer and other unwanted wildlife. Beware that these are flammable, evaporate quickly, and may be toxic to pets, birds, and children.
The most effective of the danger scents are the predator urines. These can be purchased commercially, or perhaps obtained from zoos. Contrary to what you might think, deer are afraid of not only predators they may encounter such as wolves and coyotes, but exotic animals such as lions and tigers. Soak some cotton or cloth with the product, and place in plastic containers in the garden with holes drilled in the sides. Replenish as the scent dissipates.
Not all repellents have to smell offensive to humans as well. Some pleasant scents used in products that also interfere with deer noses include mint oils (often combined with pepper and garlic), cloves and cinnamon, or citrus.
More tips on these and other methods of deer control can be found in the revised book by Rhonda Massingham Hart, Deerproofing Your Yard and Garden. Before using repellents, especially home remedies, you may want to try them on a small part of a plant to make sure they donít harm the plant. Make sure too that they wont harm people, pets, or wildlife including the deer. You want to repel them, not harm or poison them.
Beware of the many repellents on the market, some expensive or requiring repeated applications, which may or may not work. None really work for all deer in all locations, depending on so many factors such as deer preferences and population pressure (too little food for too many deer, for instance).
For best control, remember some facts about deer. They are afraid of anything new, yet learn quickly and adapt to your strategies, so try several repellents and rotate them. If you donít have a problem yet with deer in your garden, or at least a serious one, then is the best time to use deterrents. Train deer to stay away before they find your delicious garden offerings.
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