No plant is immune from deer browsing, according to the University of Maryland Cooperative Extension. Aware that deer populations differ in their preferences and that weather also plays a part, Rutgers University has compiled a list, categorizing plants from "Rarely Damaged" to "Frequently Severely Damaged." Deer may avoid some perennials because of aroma or toxicity, according to Dave Jensen, owner of Deer Resistant Landscaping Nursery in Michigan, and growing such plants can be "a fun solution."
Ornamental catmint (Nepeta) is a hardy, sun-loving perennial with purple flower-spikes and a gray-green foliage with a strong fragrance. It is this fragrance that may keep the deer away. The foliage has a slightly rough texture as well. Shear the plant back slightly after the first flush of bloom and it will reflower. It likes well-drained soil and blooms from June-July in USDA Plant Hardiness zones 3 to 8. Rutgers University lists ornamental catmint as "Rarely Damaged" in its "Landscape Plants Rated for Deer Resistance."
Rutgers University lists threadleaf coreopsis as "Rarely Damaged." Moonbeam is a variety of this coreopsis and is used widely in gardens. It prefers sun and will bloom in June with another flush of flowers after it is sheared back to remove spent blossoms. It is hardy in USDA zones 3 to 9.
Russian sage (Perovskia) is one of Dave Jensen's "Favorite 21 Plants" for deterring deer. Its silver foliage is distinctively aromatic. It blooms on flower spikes of an almost iridescent purple from July through August, slowly fading in September. It prefers a sunny, dry location and looks great in groups. The USDA zones are 4 to 9.
Fountain grass (Pennisetum) is listed on Rutgers University's list as "Rarely Damaged." It is a sun-loving ornamental grass that gets soft bottle-brush blooms in August. It prefers more water than other types of ornamental grass. It is hardy in USDA zones 5 to 9.
Monkshood (Aconitum) is a shade-loving perennial with tall flower spikes consisting of individual "hoods," hence the name. It comes in white, yellowish or bicolor, but is traditionally thought of as blue or purple. All parts are very poisonous, which the deer must sense as they usually avoid the plant, according to Jensen. Some varieties are summer-blooming and others flower in the fall. It is hardy in USDA zones 3 to 6.
Foxglove (Digitalis) is another plant on ensen's "Favorite 21 Plants." It is also a toxic plant that deer usually avoid. It will tolerate some shade, but does like the sun. Although many foxgloves are short-lived, there are perennial varieties. The plant is hardy in USDA zones 3 to 8.