The term "deer resistant" is not synonymous with "deer proof." From a botanical perspective, it signifies that a plant possesses certain physical or chemical characteristics that make it less palatable and therefore less likely to be browsed by deer compared to other, more appealing vegetation. Deer are opportunistic feeders, and their choices are influenced by availability, season, and local population pressure. A plant considered resistant in one region may be sampled in another if preferred food sources are scarce.
Coreopsis, often called tickseed, exhibits several traits that contribute to its deer-resistant reputation. The primary deterrent lies in its foliage. The leaves can be somewhat hairy or have a slightly rough texture, which is unappealing to the sensitive mouths of deer. Furthermore, the plant's sap can be mildly bitter. Many Coreopsis varieties also produce compounds, including secondary metabolites like alkaloids or sesquiterpene lactones, which can impart an unpleasant taste. While not toxic in a dangerous way, these compounds are enough to encourage deer to move on to more succulent, sweeter-tasting plants like hostas, daylilies, or tender annuals if given the option.
It is important to note that resistance can vary across the many species and cultivars within the Coreopsis genus. The classic perennial types, such as Coreopsis grandiflora and Coreopsis lanceolata, with their narrower, sometimes hairy leaves, are typically cited as the most reliably resistant. Some of the newer hybrid cultivars, bred for showier flowers and sometimes different foliage textures, may not possess the same level of defensive traits as their species ancestors. However, the genus as a whole maintains a strong standing on most reputable deer-resistant planting lists used by gardeners and landscapers.
A plant's deer resistance is not an absolute guarantee but is heavily influenced by external conditions. During a harsh winter or a period of extended drought when natural forage is limited, deer will expand their browsing options out of necessity. A hungry deer is far less discerning and may sample plants they would normally avoid, including Coreopsis. In this scenario, the new, tender growth in spring may be at a slightly higher risk than the established, tougher foliage later in the season. The level of deer pressure in a specific geographic area is also a critical factor; gardens in regions with very high deer populations will experience more testing of so-called resistant plants.
Given its general resistance, Coreopsis is an excellent choice for gardeners seeking to create a deer-tolerant landscape. Its bright, daisy-like flowers provide long-lasting color from early summer into fall, attracting pollinators while typically deterring browsing mammals. For the highest likelihood of success, it should be planted alongside other well-known deer-resistant plants such as lavender, salvia, Russian sage, and ornamental grasses. This creates a garden palette that is consistently unappetizing, reducing the chance that deer will venture in to investigate. While not a foolproof solution, Coreopsis remains a reliable and beautiful perennial for gardens in deer country.
