From a botanical perspective, "deer resistant" is not synonymous with "deer proof." It is a term that describes plants possessing certain physical or chemical characteristics that make them less palatable to browsing deer. Deer are opportunistic feeders, and their dietary choices are influenced by availability, season, and local population pressure. Resistance is conferred by traits such as toxic compounds, bitter tastes, strong scents, fuzzy or prickly textures, and sap that may be irritating. Plants like the Columbine (genus Aquilegia) have evolved some of these defenses primarily against insects but which also serve as a deterrent to larger herbivores like deer.
Columbine plants employ a multi-faceted defense strategy. Their foliage contains mildly toxic compounds, including cyanogenic glycosides. When the plant cells are damaged (e.g., by chewing), these compounds can release small amounts of hydrogen cyanide, which is unpalatable and can cause discomfort to the animal. While not potent enough to be seriously harmful, it is a significant deterrent that encourages deer to seek out more agreeable forage. Furthermore, the leaves have a slightly bitter taste, another characteristic that ranks them lower on a deer's preference list compared to tender hostas, daylilies, or roses.
The effectiveness of these defenses is highly dependent on environmental context. In areas with a high deer population and limited natural food sources, deer will browse on plants they would normally avoid, including Columbines. This is especially true in early spring when new, tender growth emerges and other food is scarce. The young, succulent leaves of the Columbine may be sampled during this period before the plant's chemical defenses have fully developed or before more preferred vegetation becomes available. Therefore, while the mature plant is generally resistant, it is not immune to browsing under extreme conditions of hunger.
When considering a garden's vulnerability to deer, it is helpful to view plants on a spectrum. Columbines are consistently ranked by horticultural institutions and extension services as "seldom severely damaged" or "occasionally severely damaged." This places them in a much more resistant category than true deer favorites like tulips or arborvitae. Their resilience is a direct result of their evolved chemical makeup. However, it is crucial to remember that the flower buds and blooms, while also containing deterrents, might be nibbled on out of curiosity, though they are rarely consumed in large quantities.
A plant's resistance can also vary by region and even by local deer herd habits. Deer in different geographic locations develop distinct feeding preferences based on what is native and available. A plant that is consistently avoided in one region might be occasionally tasted in another. The best indicator is often observation of established gardens in your immediate area. If local gardeners report that their Columbines are left untouched while other plants are ravaged, it is a strong confirmation of the plant's resistant status in that specific micro-environment.
