The Allium genus includes familiar culinary staples (onions, garlic, chives, leeks) and numerous ornamental varieties like Allium giganteum. Alliums are highly deer resistant, making them a reliable choice for landscapes where deer pressure is common. University extension guides frequently list this genus as “Rarely Damaged,” indicating deer choose almost any other food source first.
The Reason Alliums Are Unappetizing to Deer
The defense mechanism that deters deer is rooted in the plant’s unique biochemistry, specifically the presence of organosulfur compounds. These molecules are stored in a stable, non-pungent form called S-alk(en)yl-L-cysteine sulfoxides. When the plant tissue is damaged, such as when a deer bites the foliage or bulb, the sulfoxides mix with an enzyme called alliinase.
This enzymatic reaction instantly converts the stable compounds into unstable, volatile thiosulfinates, including allicin. These volatile sulfur compounds are responsible for the pungent, acrid smell and bitter taste associated with cutting an onion or crushing garlic. The compounds act as a strong irritant and repellent, signaling to the deer that the plant is unpalatable.
Deer rely heavily on their sense of smell to identify food sources, and this intense, sulfurous aroma is a significant deterrent. Even a single exploratory nibble is usually enough for a deer to learn to avoid the entire plant.
Common Allium Varieties and Their Reliability
Deer resistance extends across all types of alliums, including both edible and ornamental varieties. Edible alliums, such as garlic (Allium sativum) and chives (Allium schoenoprasum), tend to have the highest concentration of sulfur compounds. This results in a strong repellent scent and intense flavor profile, meaning these varieties are almost never touched by deer.
Ornamental alliums, grown for their striking, globe-shaped flowers, also resist browsing. Popular choices like ‘Purple Sensation’ and Allium giganteum reliably deter deer. Although some ornamental varieties may have a milder scent than culinary garlic, they still contain sufficient sulfur compounds to be unappealing.
No plant is completely immune to consumption by a severely stressed or starving deer. However, alliums are consistently placed at the bottom of a deer’s preference list. Any damage is typically limited to a small exploratory nibble rather than sustained grazing, leaving the bulb intact.
Strategic Placement in Deer-Prone Gardens
Gardeners can leverage alliums by using them strategically throughout the landscape. Interplanting alliums among more vulnerable plants creates a deterrent barrier. The strong scent released by the alliums helps mask the fragrance of nearby plants that deer find appealing, such as tulips and hostas.
Planting clumps of robust, strong-smelling alliums, like garlic or chives, along the perimeter of a flower bed creates a fragrant fence. This discourages deer from entering the area to browse. Mass plantings of ornamental alliums can also be used along property borders to establish a visual and olfactory deterrent.
Placing allium bulbs or plants near frequently browsed areas significantly reduces damage to favorite plantings. This method protects the rest of the garden without the need for fences or chemical sprays. The simple presence of the pungent plant is often enough to steer deer away.