Irises are popular garden perennials known for their striking blooms. Gardeners often wonder if these beautiful flowers will become a meal for local wildlife. Members of the Iris genus are widely considered to be deer-resistant, meaning they are rarely the first choice for browsing animals. While no plant is entirely deer-proof, irises are generally left alone due to their unappealing qualities.
Understanding Iris Deer Resistance
The classification of irises as deer-resistant stems from the availability of more palatable food sources and the inherent qualities of the plants themselves. Deer are selective grazers, and they prefer to consume plants high in moisture and nutritional value, such as hostas and daylilies. When preferred forage is abundant, irises are simply ignored.
The resistance level is consistently high across the genus, including popular varieties like the Bearded Iris (Iris germanica) and the Siberian Iris (Iris sibirica). Established plants are unappetizing because their mature foliage is often tough, stiff, or grass-like in texture. This physical characteristic acts as a deterrent, convincing the deer to move on to softer vegetation elsewhere.
Chemical Deterrents and Taste Aversion
The primary reason deer actively avoid irises lies in the plant’s natural chemical defenses, which create a strong taste and smell aversion. Irises contain compounds, such as iridin and irisine, concentrated in the rhizomes and foliage. These natural chemicals are mildly toxic and impart a distinctly bitter flavor to the plant tissue.
Deer possess an excellent sense of smell and taste, allowing them to detect these deterrents before taking a large bite. The bitter compounds signal that the plant is unpalatable or could cause digestive upset, leading them to quickly spit out any small sample they might try. This mechanism serves as a warning, ensuring irises are passed over in favor of non-toxic plants.
Protecting Iris from Hungry Deer
Although irises are generally resistant, deer will overcome their natural aversion and feed on the plants under extreme conditions, such as severe drought or heavy snow cover when usual food sources are completely unavailable. Deer may also target the tender new shoots that emerge in early spring, which have a higher moisture content and have not yet fully developed their defensive compounds.
Gardeners can take several proactive steps to protect plants during these vulnerable times, focusing on physical and sensory barriers. A temporary physical barrier, such as a short fence or netting draped over the plants, can effectively guard new plantings and spring growth until the foliage hardens. Another strategy involves the use of topical repellents, which utilize foul-tasting or foul-smelling ingredients like putrescent egg solids or garlic. These applications must be reapplied regularly, especially after rain, to maintain their effectiveness.