Jacob’s Ladder (Polemonium) is a woodland perennial popular in shade gardens for its delicate, fern-like foliage and clusters of blue or white spring flowers. Its common name comes from the ladder-like arrangement of its leaflets. When considering its place in a landscape frequently visited by wildlife, the question of its palatability often arises. Horticulturalists generally agree that Jacob’s Ladder possesses a good degree of natural protection from browsing deer, classifying it as resistant, though not entirely immune, to damage.
The Deer Resistance Rating for Jacob’s Ladder
The resistance of Jacob’s Ladder stems from a combination of chemical and physical characteristics that make it an unappealing food source. Garden plants are often assigned a resistance rating on a scale, and Polemonium species commonly fall into category ‘B,’ meaning they are “seldom severely damaged” by deer. This places the plant well outside the preferred browse of a typical deer diet.
The natural defense mechanism is partly chemical, resulting in a flavor profile that deer find bitter or otherwise disagreeable. While the plant is not toxic to deer, it contains compounds that discourage sustained feeding, causing the animal to move on to more palatable options. Jacob’s Ladder does not offer the rich nutritional rewards that would override the animal’s natural food preferences.
The plant’s physical structure also contributes to its low appeal. The delicate, pinnately compound leaves offer a texture less desirable than the broad, soft leaves of other perennials. Deer largely avoid Jacob’s Ladder because they prefer plants that are easier to digest and have a more agreeable texture.
Environmental Factors that Increase Grazing Risk
The term “deer resistant” should always be understood as a relative measure, not an absolute guarantee against browsing. Even highly resistant plants like Jacob’s Ladder can become targets under specific environmental pressures that compromise a deer’s normal foraging behavior. When natural food sources are severely limited, a deer will temporarily override its natural aversions and consume plants it would normally ignore.
This shift in diet is most commonly observed during harsh conditions, such as prolonged winter snow cover or severe drought, when preferred vegetation is unavailable. A high local deer population density also increases the overall pressure on the available food supply. In areas where competition for resources is fierce, the animals are more likely to sample and consume less palatable plants.
Another factor that can increase vulnerability is the plant’s maturity and location. Newly transplanted Jacob’s Ladder, still establishing its root system, may be more susceptible to browsing than a mature, established clump. A deer’s food preference can also vary regionally due to local herd habits and learned behaviors.
Implementing Protective Measures
For gardeners in high-pressure areas, combining natural resistance with active protection is the most effective strategy. This involves both physical barriers and chemical deterrents to create multiple layers of defense.
Physical barriers offer the most reliable protection, especially for young, vulnerable plants. Temporary, small-gauge wire cages or netting can be placed over individual Jacob’s Ladder plants for the first growing season to allow them to establish without damage. For protecting a larger area, a full-perimeter fence is the most dependable solution, though it needs to be at least seven to eight feet tall to effectively deter a determined deer.
Repellents work by either taste or scent, and both types require consistent reapplication. Scent-based repellents often contain putrescent egg solids or meat proteins that mimic a predator’s odor, causing the deer to avoid the area entirely. Taste-based products use bittering agents and must be applied directly to the foliage, requiring the deer to take a bite to be effective. It is advisable to rotate the type of repellent used to prevent the deer from becoming habituated to a single deterrent.