There are a variety of options to limit damage caused by deer. Many are effective to a degree, when used properly.
The reality is, while some plants are less desirable to deer, no plant is deer-proof. Lists of “Deer Resistant” plants are readily available, unfortunately dietary preferences of deer frequently change and what once was undesirable can soon become their favorite. As a general rule, deer don’t like plants with coarse, bristly, fuzzy, thorny, or spiny textures, and they also dislike plants with strong aromas.
Surrounding an entire garden or crop is the most effective and expensive means of preventing damage by deer. Fencing should be made of wire to discourage deer from eating the mesh and should be at least 8 feet (2.2 meter) tall as deer are excellent jumpers. An alternative is to use a solid fencing material that deer are unable to see through as they will not attempt to jump over a fence when they cannot see what is on the other side.
Individual plants can be protected by wire baskets and structures made of wire. Mesh must be small enough to discourage deer from pulling foliage through with their tongues. Deer can be very determined so wire must be securely anchored to the ground.
Electric fencing can be used as either a stand-alone deterrent or in conjunction with other deer repellent strategies. The electrified wire encircles the entire property to be protected and acts as a negative stimulus deterrent. A bait or attractant is often attached to the fence. When deer attempt to eat the bait they receive a painful, though non-lethal shock. It is thought that deer will begin to associate pain with the specific area being protected, causing them to alter their eating habits. Electrified wires should be spaced 18 inches (.5 meter) at the most, with a total height of 7 feet (2.2 meter).
Deer repellent sprays have a foul stench that repels deer (and humans). Most commercially available and homemade sprays are derived from rotten eggs, putrefied meats or chilli powders and must be reapplied periodically, and after each rain. Deer repellent sprays should not be used on plants that are to be eaten and the noxious smell may make them unsuitable around homes or people.
When deer come in range the motion sensor triggers the sprinkler which startles deer into leaving the immediate area. Deer soon realize the water is no threat and have been seen intentionally triggering the device in order to get a drink or cool off. The devices must be connected to a garden hose that is always turned on, making them impractical for remote locations or areas subject to freezing.