Morning glories (Ipomoea) are fast-growing, annual vines prized for their beautiful, trumpet-shaped flowers and rapid coverage on trellises and fences. Homeowners in areas with high deer populations often worry about potential browsing damage to the lush foliage. The common question is whether these popular climbers will survive the appetites of white-tailed deer. Understanding the biological compounds within the plant provides the clearest answer.
Deer Palatability and Morning Glory Toxicity
Deer generally classify morning glories as a low-preference food source, often left alone when more palatable vegetation is available. This avoidance stems from the plant’s natural defense mechanisms involving indole alkaloids, such as lysergic acid amide (LSA or ergine). These compounds are concentrated heavily in the seeds, but are also present in the leaves and stems of the vine.
The alkaloids impart an unpleasant, bitter taste to the foliage, which deer detect during initial browsing. Ingesting these compounds can also cause mild digestive distress, conditioning the deer to avoid the plant in the future. Due to this chemical deterrent, many ornamental varieties of Ipomoea are categorized by agricultural extensions as “rarely damaged” by deer.
Factors That Increase Deer Foraging
While morning glories possess chemical defenses, deer are opportunistic feeders, and avoidance is not guaranteed. When preferred food sources become scarce, such as during drought or harsh winter months, deer will shift their diet to “marginal” foods they typically ignore. In these situations of nutritional stress, the need for calories outweighs the aversion to the bitter alkaloids.
Tender, new growth is also more susceptible to browsing, as young leaves have a lower concentration of defensive chemicals than mature foliage. Deer are attracted to the soft texture and high protein content of new sprouts, which are important for their growth, especially for pregnant does in the spring. Regional differences in deer population density and local dietary habits can also influence whether a specific patch is targeted.
Practical Methods for Plant Protection
Gardeners who experience persistent deer browsing can employ physical and chemical strategies to protect their vines. Physical barriers offer the most reliable protection, especially for young, vulnerable plants. A temporary cage constructed of wire mesh or netting can be placed around the base until the plant grows taller than the deer can easily reach. For more permanent protection, a strategic double-fence line can be highly effective, as deer are less likely to attempt a jump if they cannot clearly see a landing space between two fences.
Repellents are another option, working by taste or odor to make the plant unappealing. Commercial sprays often use ingredients like putrescent egg solids or capsaicin to deter feeding. The effectiveness of any repellent relies on consistent reapplication, particularly after rain or new growth emerges. A combination of scent-based deterrents and physical barriers often provides the best defense against determined deer.
Similar Climbing Plants Deer Avoid
For gardeners seeking the aesthetic appeal of a climbing vine with a higher degree of deer resistance, several alternatives offer beautiful foliage and flowers. Clematis vines, with their woody stems and large, showy blooms, are generally avoided due to their somewhat bitter foliage. While deer may occasionally sample a tender shoot, they rarely cause severe damage to the entire plant.
Wisteria is another excellent choice, providing a robust, woody structure and highly fragrant, drooping flower clusters that deer consistently pass over. American bittersweet is also highly resistant, primarily because its fruit is toxic to many mammals, although its vines are non-toxic to birds.