From a botanical perspective, lupines (Lupinus spp.) are generally considered deer-resistant, though not entirely deer-proof. This resistance is primarily attributed to their unique chemical composition. Lupines produce a variety of alkaloids, such as lupinine and sparteine, which are concentrated in the foliage, stems, and seeds. These compounds are bitter-tasting and can be toxic to many mammals, including deer. When a deer samples a lupine plant, the unpleasant taste and potential for digestive discomfort act as a powerful deterrent, encouraging the animal to seek out more palatable vegetation elsewhere in its environment.
The physical structure of the lupine plant also contributes to its deer resistance. The leaves are palmately compound, meaning multiple leaflets radiate out from a single point, creating a texture that is not as appealing to deer as the broad, soft leaves of hostas or daylilies. Furthermore, some species have slightly hairy or rough leaf surfaces, which are less desirable from a grazing perspective. The vertical flower spike, while attractive to pollinators, does not present the easily accessible, bulk foliage that deer typically prefer to browse on.
A plant's resistance to herbivory is not an absolute trait but is highly dependent on external conditions. During periods of extreme drought or in late winter when preferred food sources are exceptionally scarce and deer populations are high, a hungry deer may resort to eating plants it would normally avoid, including lupines. The concentration of deterrent alkaloids can also vary between species and even individual plants based on soil chemistry, sunlight, and overall plant health. A stressed lupine might produce fewer defensive chemicals, potentially making it marginally more vulnerable.
In the hierarchy of deer preference, lupines rank low. They are significantly less palatable than many common garden plants like roses, tulips, or hydrangeas. A deer will almost always choose these tender, sweet options over a bitter lupine. Therefore, in a garden setting, planting lupines can be an effective strategy for reducing deer damage. They serve as a reliable, defensive perimeter or can be interplanted with more vulnerable species, though this is not a guaranteed protection method. It is important to note that while the foliage is unappealing, deer have been known to occasionally nibble on the flower spikes, though they rarely consume the entire plant.
For a gardener in deer-prone areas, understanding lupines from this plant-centric viewpoint is crucial. While they are a excellent choice for a "deer-resistant" garden, they should be part of a broader strategy that includes other unpalatable plants. It is also vital to be aware that all parts of the lupine plant, particularly the seeds, are highly toxic to humans and pets if ingested. Their defensive chemicals, which successfully deter deer, are potent and must be respected. Establishing young lupine plants may require protection, such as a temporary spray deterrent or physical barrier, until they are established and their alkaloid production is at full capacity.
