Gladiolus, often called "glads" or sword lilies, are herbaceous perennial plants belonging to the Iridaceae family. They are characterized by their tall flower spikes, which can range from two to six feet, and their long, sword-shaped (gladiatorial) leaves. From a botanical perspective, the plant's survival strategy revolves around its corm—a swollen, underground plant stem that stores nutrients to fuel the growth of the spectacular flower spike each season. This reproductive strategy is energy-intensive, and the plant has developed certain characteristics to protect this investment.
In the plant kingdom, "deer resistance" is not an absolute guarantee but a spectrum of defensive adaptations. Plants deploy various physical and chemical strategies to deter herbivores. Physical defenses include thorns, spines, tough or fuzzy leaves, and unpleasant textures. Chemical defenses involve producing secondary metabolites like alkaloids, tannins, or essential oils that make the plant taste bitter, cause digestive upset, or are outright toxic. A plant is considered "deer resistant" if it possesses one or more of these traits that make it less palatable than other, more appealing garden varieties.
Unfortunately for gardeners, Gladiolus are not considered a reliably deer-resistant plant. They lack many of the key defensive traits that deer find off-putting. Their leaves are smooth, tender, and not fibrous, making them easy for deer to chew and digest. More importantly, the flower spikes themselves are a significant attractant. The large, brightly colored, and nutrient-rich blooms are a high-value food source. Deer are particularly drawn to the flower buds and open flowers, which they will readily consume, often severing the entire spike from the plant and leaving the gardener with a headless stalk.
Examining the gladiolus reveals its vulnerabilities. Physically, it has no thorns, prickles, or tough, leathery foliage to make eating difficult. Its texture is consistently soft and appealing to a deer's palate. Chemically, while the corms of some Gladiolus species can be toxic to certain animals if ingested in large quantities, the above-ground vegetative and floral parts do not produce significant concentrations of repellent chemicals. They do not possess the strong aromatic oils found in truly resistant plants like lavender or sage. Consequently, to a deer, a gladiolus represents a tall, easy-to-access, and nutritious snack, not a protected or unpleasant one.
Given their low resistance, protecting gladiolus requires strategic human intervention. The most effective method is physical exclusion through tall, sturdy fencing. Alternatively, interplanting gladiolus among plants that are truly deer-resistant can sometimes help mask their presence. Good companion plants are those with strong scents deer dislike, such as lavender, catmint, or Russian sage, or those with fuzzy or tough leaves like lamb's ear or peonies. However, this method is not foolproof, as a hungry deer will still seek out the prized gladiolus blooms despite the surrounding less-palatable foliage.
