Home growers often seek plants that naturally resist browsing in areas with high deer populations. Deer are opportunistic herbivores, but they have distinct preferences, which often exclude certain plant families. The Allium genus, which encompasses common edibles like onions, garlic, and chives, along with various ornamental varieties, offers a reliable solution. Identifying plants deer actively avoid is key to creating a landscape that is less appealing to these animals.
Why Alliums Are Generally Avoided by Deer
Deer typically avoid plants belonging to the Allium family, which is why these species are consistently classified as deer-resistant. This avoidance is a behavioral response driven by immediate sensory cues, primarily smell and taste. Deer rely heavily on their sense of smell to determine the palatability and safety of a potential food source.
The strong, pungent aroma and flavor produced by alliums act as a natural deterrent, signaling to the deer that the plant is unpleasant to consume. The intense odor is recognizable even before the animal takes a bite, causing it to quickly seek alternative forage. Gardeners often use alliums, such as chives or ornamental onions, to create a perimeter that helps shield more vulnerable plants like tulips or hostas from browsing pressure.
The Chemical Basis of Deer Repulsion
The deer’s strong aversion to the Allium genus is rooted in the plant’s unique biochemistry. When the plant tissue is damaged, whether by chewing or crushing, it releases specialized sulfur-containing compounds. These volatile organic compounds are responsible for the characteristic sharp odor and taste associated with onions and garlic.
These compounds include various organosulfur molecules, such as allyl sulfides, which are held in the plant cells until the tissue structure is compromised. Upon damage, an enzymatic reaction rapidly converts odorless precursor molecules into highly pungent, sulfurous gases. For deer, the resulting aroma and taste are overwhelmingly unpalatable, triggering a distinct stop signal. This chemical defense mechanism evolved to discourage herbivores from consuming the plant.
Contexts Where Deer Might Still Browse Alliums
While alliums are widely considered deer-resistant, no plant is entirely deer-proof. The level of deer browsing pressure in a given area can override a plant’s natural defenses under certain conditions. Extreme food scarcity, particularly during harsh winters when other forage is unavailable, may compel a desperate deer to try plants it would normally ignore.
Deer may occasionally nibble on the soft, new growth of allium shoots that emerge in the early spring. These young tissues may not have fully developed the maximum concentration of defensive organosulfur compounds, making them slightly less potent. Furthermore, effectiveness varies between the hundreds of species within the Allium genus; while culinary garlic and onions are potent, some ornamental varieties may possess a less intense chemical profile.