Lupines (Lupinus spp.) are generally considered to be deer-resistant plants, though this term is better understood as "deer-tolerant." No plant is entirely deer-proof if pressure is high and food sources are scarce. However, lupines possess several inherent physical and chemical traits that make them unpalatable and undesirable to deer. They are rarely the first choice for a browsing deer and will typically be left alone in favor of more tender, succulent plants like hostas, daylilies, or roses. This resistance makes them an excellent candidate for American landscapes in areas with moderate to heavy deer pressure.
The primary reason for the deer resistance of lupines lies in their chemical composition. Many lupine species, particularly the native North American varieties, produce a variety of bitter-tasting alkaloids. These compounds, such as lupinine and sparteine, are toxic if ingested in large quantities. While deer may sample a plant once, the unpleasant taste and potential for mild toxicity act as a powerful deterrent, training the deer to avoid the plant in the future. It is important to note that alkaloid content can vary between species and even within cultivars. Some modern horticultural hybrids may have been bred to reduce alkaloid levels, which could potentially make them slightly more palatable, though they largely retain their resistant status.
Beyond their chemical defenses, the physical structure of the lupine plant is also unappealing to deer. The leaves are palmately compound, meaning multiple leaflets radiate from a central point. These leaflets are often tough and have a slightly hairy or fuzzy texture. Deer prefer plants with smooth, soft, and fleshy foliage that is easy to digest. The coarse, textured leaves of the lupine are simply not as attractive or easy to eat as other garden plants. Furthermore, the flower spikes, while beautiful to humans, do not offer the soft, nutrient-rich browse that deer seek out.
While lupines are a reliably deer-resistant choice, their performance can be influenced by local conditions. In times of extreme drought or in late winter when preferred food sources are exceptionally scarce, a hungry deer may browse on plants they would normally avoid, including lupines. This is more likely to happen with young, newly emerging shoots that might be slightly more tender. Additionally, the specific species planted can matter. The native Sundial Lupine (Lupinus perennis) is renowned for its strong resistance. When selecting plants, opting for species known for higher alkaloid content will provide the best defense against deer browsing.
