Coreopsis, commonly known as Tickseed, is a popular garden perennial celebrated for its cheerful, daisy-like flowers and long bloom season. Concerns often arise about their vulnerability to deer browsing, especially for homeowners gardening in areas with high deer populations. This article examines the specific resistance of Coreopsis to deer and offers practical solutions for protecting your landscape.
Coreopsis and Deer: The Resistance Verdict
Coreopsis is widely classified as a deer-resistant plant, meaning it is rarely a preferred food source for these animals. While no plant is entirely “deer-proof,” Coreopsis is left alone due to characteristics that make it unappealing to browsing animals. This resistance holds true across many common varieties, including the fine-textured Coreopsis verticillata and the broader-leaved Coreopsis grandiflora.
Deer only target these plants when their preferred, more palatable food sources are scarce. Situations such as severe drought or extremely high deer population density can increase browsing pressure on resistant plants. However, under normal conditions, Coreopsis minimizes the risk of significant deer damage.
Factors That Influence Plant Palatability to Deer
The primary reasons deer avoid certain plants relate to their sensory experience and the nutritional return of the foliage. Plants with a tough or unpleasant texture are often passed over by deer seeking softer, more succulent leaves. This includes foliage that is fuzzy, prickly, or possesses a thin, fine texture, which is less satisfying than broad, tender leaves.
Deer also rely heavily on their sense of smell, frequently avoiding plants that produce strong, pungent aromas. These strong scents are caused by aromatic oils and chemical compounds that signal bitterness or mild toxicity, making the plant unappetizing.
Coreopsis species often possess a fine or tough texture and may contain bitter compounds, contributing to their low palatability. Additionally, plants that offer a low concentration of protein and carbohydrates, requiring deer to consume large volumes for minimal nutrition, are often ignored.
Adjusting Your Garden When Resistance Fails
If deer pressure in your area is unusually high, or if young, tender growth is being browsed, several mitigation strategies can be employed.
Physical barriers offer the most reliable protection. Fencing must be at least seven to eight feet tall to prevent deer from jumping it. For smaller areas, a micro-exclosure—a small, solid fenced compound—can deter deer psychologically since they avoid confined spaces.
Repellents are a second line of defense, working by using a scent or taste offensive to deer, such as hot pepper, garlic, or a rotten egg mixture. To maintain effectiveness, rotate the type of repellent used, as deer quickly become accustomed to a single scent or taste.
Strategic planting also helps, such as interspersing highly resistant, aromatic plants like lavender or sage among less-resistant species to mask the scent of their preferred food.