Gladiolus, often called "glads," are flowering plants prized for their tall, striking flower spikes and vibrant, sword-shaped leaves (from which they get their name, as 'gladius' is Latin for sword). From a botanical and ecological perspective, a plant's resistance to deer is largely determined by its physical and chemical defenses. Gladiolus are herbaceous perennials that grow from corms. They do not possess strong physical deterrents like thorns or a woody, tough texture. More importantly, their foliage and blooms are not known to contain significant levels of toxic or unpalatable chemical compounds, such as the alkaloids, iridoid glycosides, or milky sap found in truly deer-resistant plants like daffodils, foxgloves, or milkweed.
Deer are opportunistic browsers with a highly adaptable diet. Their food choices are influenced by availability, season, and the inherent tastiness (palatability) of the plant. In the context of your garden, deer tend to categorize plants into two groups: those they will eat and those they will avoid. Gladiolus, unfortunately, fall squarely into the first category. The tender, succulent foliage and the carbohydrate-rich corms underground are both highly attractive and nutritious food sources for deer, especially in suburban areas where their natural foraging grounds are limited. During times of scarcity, such as late fall or a harsh winter, deer are even more likely to browse on any available vegetation, making prized ornamentals like glads a prime target.
Based on their plant characteristics and observed deer behavior, Gladiolus are not classified as deer-resistant. In fact, they are often listed among a deer's favorite garden plants. The new, tender growth in the spring is particularly vulnerable to being nibbled down to the ground, which can prevent the plant from flowering altogether. Even if the foliage is left alone, the tall flower spikes, which are the main reason for growing glads, are a conspicuous and tempting treat. A deer can easily decapitate a spike full of blooms in a single bite. Therefore, if you live in an area with a moderate to high deer population, assuming they will leave your gladiolus untouched is a recipe for disappointment.
While the plant itself is not resistant, you can employ several strategies to protect your gladiolus investment. The most effective method is physical exclusion. Installing a sturdy fence at least 8 feet tall around your garden is the only guaranteed way to keep deer out. For a less imposing solution, individual protective measures can be highly effective. Planting gladiolus corms inside cylindrical wire cages buried in the planting hole can protect the corms from being dug up and eaten. Additionally, the use of chemical deterrents can offer some protection. These are sprays that make plants taste bad or smell unpleasant to deer. However, they must be applied frequently, especially after rain or watering, and their efficacy can vary as deer may become accustomed to them over time.
