The Leyland Cypress is a fast-growing evergreen popular for creating dense privacy screens. While generally considered deer-resistant, this classification often leads to misunderstanding, as the tree is not entirely deer-proof. Its resistance is nuanced, depending heavily on environmental factors and the available food supply.
The Level of Resistance
The term “deer-resistant” indicates low palatability compared to other vegetation, not a guarantee against browsing. Official classifications vary; some university data places Leyland Cypress in the “occasionally to frequently damaged” category. This suggests that while it is not a preferred food source, browsing damage is common, especially in areas with high deer populations.
A more accurate description is that the plant is “seldom severely damaged” under normal foraging conditions. Deer ignore it when preferred foods, such as hostas, arborvitae, or flowering shrubs, are abundant. However, damage increases significantly when preferred food sources become scarce. Planting Leyland Cypress does not eliminate the need for protective measures in landscapes frequented by deer.
Characteristics That Deter Deer
Deer behavior is largely influenced by a plant’s texture and chemical composition. The Leyland Cypress possesses features that contribute to its low appeal, primarily aromatic compounds known as terpenes contained within its scale-like leaves. These volatile organic compounds are responsible for the tree’s pleasant, pine-like scent when the foliage is crushed.
Terpenes serve as a natural defense mechanism in many plants, often imparting an unpalatable or bitter taste to herbivores. While the foliage is not prickly or rough, the internal chemistry provides a degree of protection. Deer often “sample” plants based on scent before committing to browsing, and the distinctive aroma can signal the presence of these deterrents, causing them to move on.
Specific Scenarios Where Browsing Occurs
Despite the mild deterrents, specific circumstances increase the Leyland Cypress’s vulnerability to deer browsing. The most significant factor is nutritional stress, which occurs during harsh winters, prolonged droughts, or periods of heavy snow cover. When a deer’s primary food sources are depleted or inaccessible, the animal will consume almost any available vegetation to survive, overriding its usual food preferences.
Younger trees and new growth are particularly susceptible to browsing damage because their foliage is softer and more tender than mature growth. Newly planted Leyland Cypress specimens, or those that have been heavily fertilized, can present lush, easily digestible material that is appealing to deer. Additionally, local deer populations can develop distinct feeding habits, meaning deer in one region might routinely browse a plant ignored by deer in another area.
Damage from Antler Rubbing
Damage sometimes attributed to feeding is actually caused by antler rubbing. Male deer, or bucks, rub their antlers on the bark of small trees in the fall to remove the velvet covering and mark their territory. This mechanical damage can strip the bark completely around the trunk, a process called girdling. Girdling severs the tree’s vascular system and can lead to the tree’s death, regardless of the foliage’s palatability.