Deer browsing in gardens often leads gardeners to seek natural deterrents, and the pungent bulb of garlic is frequently suggested. Deer have a highly developed sense of smell, which makes them sensitive to strong odors. Garlic is a member of the allium family, known for intense aromas and flavors that are generally unappealing to grazing animals. The question is whether this natural aversion provides reliable protection for vulnerable plants.
The Direct Answer: Why Deer Avoid Garlic
Garlic is widely considered deer-resistant because deer consistently avoid eating it. This avoidance stems from the plant’s chemical defense system, which creates a strong, spicy aroma and unpalatable taste. When the garlic plant is crushed, enzymes convert sulfur-containing compounds into allicin and other thiosulfinates.
Allicin is the compound primarily responsible for garlic’s pungent smell and flavor. This strong sulfurous odor acts as a deterrent for deer, whose sense of smell is acute. This natural mechanism is why growing garlic is typically left untouched by browsing deer. Deer are adept at remembering spots with poor-tasting forage, helping them avoid the plant after an initial sample.
Using Garlic as a Protective Companion Plant
The powerful odor emitted by garlic can be strategically used to protect nearby, desirable plants through companion planting. Garlic’s strong scent acts as a masking agent, confusing the deer’s sensitive olfactory system. By overwhelming the air with its pungent aroma, garlic can effectively hide the appealing scent of vulnerable plants like hostas, tulips, or vegetables.
Planting garlic cloves around the perimeter of a garden bed creates a dense, aromatic barrier. This consistent release of sulfurous compounds provides an area-based repellent effect. The deer perceive the entire zone as an undesirable feeding location and graze elsewhere.
Practical Methods for Applying Garlic-Based Repellents
Gardeners can utilize garlic’s repellent qualities by applying a simple, homemade spray mixture directly onto vulnerable foliage. A basic recipe involves blending crushed garlic cloves with water and incorporating liquid dish soap to help the solution adhere to the leaves. For example, one bulb of crushed garlic mixed with a gallon of water and dish soap creates an effective contact repellent. Allowing the mixture to sit for 24 hours before straining can increase its potency.
The soap acts as a surfactant, ensuring the garlic mixture sticks to the waxy surfaces of the leaves. The goal is to saturate the leaves and stems of favored plants, making them taste and smell unpleasant. Gardeners can also strategically plant whole garlic cloves or bulbs around the edges of a garden to create a physical barrier that slowly releases scent.
Sprays must be reapplied frequently to maintain effectiveness, especially after significant rainfall washes the repellent compounds away. Reapplication is recommended every one to two weeks, or immediately following a heavy rain event. Focusing the application on new growth is important, as deer prefer the tender, untreated shoots that emerge after spraying.
Factors That Can Reduce Garlic’s Effectiveness
While garlic is a strong deterrent, its effectiveness is not absolute and can be reduced by several factors. The primary limitation is a deer’s level of hunger. A starving deer, particularly during harsh winter conditions or drought, may overcome its natural aversion to garlic’s taste and odor. In these high-pressure situations, the need for calories can override the repellent effect.
Heavy or prolonged rain will significantly reduce the potency of topical garlic sprays by washing the active sulfur compounds off the plant surfaces. The need for reapplication after rain is a practical drawback of all contact-based repellents. Finally, young garlic shoots may occasionally be sampled by deer before the concentration of allicin fully develops, as the early growth can be more tender and less intensely flavored than the mature bulb.