The Cardinal Flower, Lobelia cardinalis, is a striking perennial known for its towering spikes of vibrant, scarlet-red blossoms. Native to damp areas across the Americas, this plant is a favorite among gardeners seeking to attract hummingbirds and butterflies to their landscape. Its intense color and relatively low maintenance make it a desirable addition to rain gardens and moist borders. The presence of deer, however, often prompts questions about the safety of new plantings.
Toxicity and Deer Avoidance
The Cardinal Flower is generally regarded as highly resistant to deer browsing, a characteristic stemming from its natural chemical defenses. All parts of the plant are toxic if ingested, containing a complex mixture of pyridine alkaloids, such as lobelamine and lobeline.
These alkaloids serve as a powerful deterrent because they impart a bitter taste and can cause unpleasant symptoms in mammals, including nausea, vomiting, and weakness. Deer are selective browsers; they typically sample the plant and quickly learn to avoid it due to the unpalatable flavor and potential gastric distress. This chemical protection is the primary reason why Lobelia cardinalis is not a preferred food source and is widely classified as deer-resistant.
Situational Factors Affecting Browsing
While the Cardinal Flower possesses strong natural defenses, its resistance is not absolute, and damage reports occur in certain environmental conditions. Deer may resort to desperation browsing when under extreme pressure, such as during periods of food scarcity like severe drought or deep winter snow.
Browsing damage is also closely linked to local deer population density. High deer numbers force animals to consume plants they would normally ignore due to competition for food. Younger plants or new growth may also be softer and contain fewer defensive alkaloids than mature foliage, making tender seedlings slightly more vulnerable to an initial sample.
Practical Protection Measures
Gardeners facing persistent deer pressure can implement several strategies to safeguard Cardinal Flowers, especially newly planted specimens. Physical exclusion is the most reliable method, involving temporary cages or netting around new plantings until they become established. For larger areas, a tall fence can be effective, though this is often impractical for small garden beds.
Chemical and scent-based deterrents offer another layer of protection. Commercial deer repellents, which utilize foul-smelling or bitter-tasting ingredients, can be sprayed directly onto the foliage. Granular repellents can also be sprinkled around the base of the plants for a longer-lasting effect. Motion-activated sprinklers, which use a sudden burst of water, are also successful in startling deer away from the area.