The stock flower, Matthiola incana, is a popular choice for gardeners due to its dense, colorful blooms and characteristic sweet, clove-like fragrance. Its presence in landscapes shared with wildlife raises a common question about its vulnerability to browsing deer. While no plant is entirely immune to a hungry herbivore, the stock flower generally places low on a deer’s preferred menu. Understanding these natural defenses and the circumstances that override them is the first step in successful gardening.
The Palatability of Stock Flowers to Deer
Stock flowers possess natural defenses that make them unfavorable compared to softer, more succulent plants. They are broadly classified as deer-resistant, meaning they are seldom severely damaged by browsing. This resistance stems primarily from the plant’s texture and its distinct volatile organic compounds.
The leaves of Matthiola incana have a hairy or grayish-white appearance, often described as “hoary,” indicating a slightly rough texture. Deer are highly selective feeders that tend to avoid foliage with fuzzy or coarse textures that feel unpleasant to chew. The plant’s notable clove-like scent, while pleasant to humans, acts as a chemical deterrent to deer.
Deer rely heavily on their sense of smell to evaluate potential food sources; strong aromatics often signal bitter or unpalatable compounds. The Brassicaceae family, to which stock flowers belong, contains compounds that contribute to this avoidance. Consequently, where deer have access to varied forage, stock flowers are typically bypassed in favor of plants that are easier to digest and lack strong flavors or textures.
Environmental Factors That Increase Browsing Risk
Although stock flowers are generally avoided, no plant is truly deer-proof, and external conditions can drastically change a deer’s feeding habits. The primary factor overriding natural plant resistance is intense competition for food, particularly in areas with high deer population density. When preferred forage is exhausted, deer are forced to test less palatable options, including resistant ornamentals.
Seasonal hunger is another significant variable, especially during late winter and early spring when natural browse is scarce. During these periods, the new, tender growth of spring-planted stock flowers becomes more attractive. Young shoots contain higher levels of non-structural carbohydrates and are less fibrous than mature foliage.
Similarly, in summer drought conditions, the moisture content of an irrigated garden plant can make it a temporary target even if its taste is undesirable. If deer pressure is consistently high, the risk of browsing increases regardless of the plant’s inherent resistance. This sustained pressure forces deer to adjust their diet, leading them to consume plants they would normally ignore. This demonstrates that the plant’s resistance is relative, not absolute, and can be easily overcome by hunger.
Implementing Physical and Olfactory Deterrents
If deer begin to browse on stock flowers, gardeners should employ a rotation of specific deterrent methods focused on physical exclusion and sensory offense.
Physical Barriers
The most reliable physical barrier is a permanent fence, which typically needs to be seven to eight feet high to prevent deer from successfully jumping over it in a single leap. Where high fencing is impractical, a double-fence system can be installed, consisting of two four-foot-tall barriers spaced four to five feet apart. Deer are reluctant to jump into a confined space where they cannot safely land or judge a clear escape path, making this lower barrier highly effective. For individual plants or small beds, temporary netting or cloches can offer immediate protection during the vulnerable new growth phase.
Olfactory and Taste Deterrents
Olfactory and taste deterrents provide a separate line of defense and should be rotated to prevent the deer from becoming accustomed to a single product. Commercial repellents often contain active ingredients like putrescent egg solids, which emit a sulfurous odor signaling decay, or capsaicin, which provides a distasteful burning sensation. Rotating between an egg-based product and a capsaicin-based product, perhaps alternating with a garlic or mint oil spray, ensures the sensory cue is constantly changing, reinforcing the plant’s unpalatability.