Everyone knows a hungry deer will eat anything (or at least try to). Still, a selection of deer resistant plants worked into your landscape remains a part of an overall deer proofing strategy. Retailers and local gardening groups are really good at sharing lists of local deer resistant plants, but for many folks, it still remains a mystery as to why some plants are deer resistant and why others aren’t. Deer resistance is generally about two things: texture and volatile oil content.
Just like my nine-year-old who won’t eat anything mushy, deer have textures they prefer and textures they avoid. Deer love young, tender, herbaceous plants with a mostly smooth texture. They tend to avoid leaves with spiny tips (aristae) like you find on hollies and agarita. Leaves that are very fuzzy, such as on many sages, are also not appealing to deer as are leaves that are heavily ruffled, such as on your mints or on a split leaf philodendron. Spiny leaves, such as needles on conifers and those on an asparagus fern are also not a deer favorite. Deer also avoid plants with leaves that have a heavy cuticle layer, which give it that glossy, waxy appearance. Those types of plants tend to have thicker leaves, and many times they also have aristae on their tips.
Volatile Oil Content
Volatile oils are the components in plants that tend to give them their fragrance and flavor. Many herbs are high in volatile oils. Plants such as mint, sage, thyme, rosemary, and lavender all have high volatile oil content that make them both very fragrant and very tasty to humans — and equally nasty to deer. Their ornamental counterparts also contain those volatile oils, such as your salvias like Autumn Sage. Often, those same volatile oils can irritate folks with sensitive skin. Often native lantana and junipers cause skin irritation, in addition to being highly fragrant. As a result, deer tend to avoid making contact them.
Its important to note that the deer resistant varieties tend to be the original native species that naturally evolved, and not the variants bred by growers. Often, to achieve certain qualities desirable by homeowners (e.g. different flower colors), the volatile oils and other deer resistant qualities of a plant are bred out and replaced with a more docile, albeit very pretty offspring. So, it’s best to look for the native, or “original” variety, for any plant species that is offered up as a deer resistant option.
Another key consideration to remember is that deer resistant plants do not become deer resistant until they are established and have matured. Often, they don’t achieve their tell-tale leaf structures, thorns and aristae, and high oil content until they have fully developed. This also means that young, fresh growth on established deer resistant varieties can be susceptible to nibbling by deer.
Of course, there are always exceptions. One common deer resistant plant in my area is the Texas Columbine. With small, tender leaves and dainty flowers, it looks as if it would be deer candy, but it is generally pretty good at holding its own in the landscape. And, as always, in drought conditions and areas where new development is encroaching into deer territory, nothing is safe, not even the plants deer hate the most. Which is why a sound approach to deer proofing your garden employs multiple strategies, not just plants, and, like anything in gardening, a healthy dose of patience and a lot of experimentation.