Brunnera, commonly known as Siberian Bugloss, is a favored perennial for shaded garden spaces, prized for its striking foliage and delicate sprays of blue, forget-me-not-like flowers in the spring. The plant forms attractive clumps of large, heart-shaped leaves that provide texture and brightness where light is limited. Preventing damage from browsing deer is a common challenge for gardeners who cultivate ornamental plants. Understanding a plant’s natural defenses is important for garden planning, and this article examines the natural resistance of Siberian Bugloss to deer and the circumstances under which that resistance may fail.
Brunnera and Deer Resistance
Brunnera is widely classified by horticultural experts as a highly deer-resistant perennial. While no plant is truly “deer-proof,” Brunnera is seldom browsed unless deer are under extreme pressure. The plant’s inherent characteristics make it an unappealing food source, causing deer to bypass it in favor of smoother, more palatable foliage. Deer typically prefer plants that are easy to consume and digest, meaning Brunnera is usually one of the last plants chosen from a garden buffet. Brunnera is often placed in the same category of resistance as plants like daffodils and ferns.
The Characteristics That Deter Deer
The primary factor contributing to Brunnera’s high resistance is the physical texture of its foliage. The large, heart-shaped leaves of Brunnera macrophylla possess a distinctly rough and slightly hairy surface. These minute hairs, or trichomes, create a coarse texture that is unpleasant for deer to chew, as they generally favor smooth, tender vegetation. This coarse texture acts as a mechanical deterrent, making the plant less appealing than many alternatives. Unlike other resistant plants that rely on strong-smelling or bitter chemical compounds, the tactile experience is the dominant defense mechanism for Brunnera. Deer rely heavily on their sense of touch when selecting food, and the rough surface signals an undesirable meal.
When Deer Might Still Browse Brunnera
Despite its natural defenses, resistance does not equate to immunity, and deer browsing can still occur under specific environmental conditions. The most common reason for resistance failure is extreme food scarcity, such as during severe drought, prolonged deep snow cover, or periods of high deer population density. In these situations, a starving deer will consume almost any available vegetation to survive, overriding its typical food preferences. Newly planted specimens are also more vulnerable than established clumps. The fresh, tender growth that appears in spring often lacks the full coarseness of mature foliage, making it temporarily more palatable to a passing deer. Regional variations in deer diet and local availability of preferred food sources mean that deer behavior can differ, so what is safe in one area might be occasionally sampled in another.
Active Protection Methods
If a garden is situated in an area experiencing heavy deer pressure, relying solely on natural resistance may be insufficient. Short-term protection for new plantings can be achieved with temporary physical barriers, such as placing a wire cage or netting around the individual Brunnera plant until it establishes mature foliage. This provides a physical block during the plant’s most vulnerable phase. For long-term protection, gardeners can employ topical repellents that work by taste or smell. These commercial products, which often contain ingredients like putrescent egg solids or capsaicin, must be reapplied regularly, especially after heavy rain or as new leaves emerge. Rotating between different types of repellents prevents deer from becoming accustomed to a single deterrent, maintaining the protective effect.