Asters are popular perennial flowers known for their abundant, daisy-like blooms that provide late-season color in gardens across North America. As preferred food sources diminish toward the end of the growing season, gardeners often worry whether these plants will be targeted by deer. Deer browsing pressure dictates plant selection, making resistance a major factor in garden planning. Understanding the feeding behaviors of deer is the first step toward successfully cultivating these vibrant fall staples.
The Definitive Answer: Palatability of Asters
Deer do not typically prefer asters, but they are susceptible to browsing damage, particularly when other food sources are scarce. Asters are generally classified as “seldom severely damaged,” meaning only minor nibbling is expected under normal circumstances. This places them on the lower end of the palatability scale compared to highly favored plants like hostas or tulips.
The risk of damage increases significantly during periods of environmental stress, such as drought or deep winter snow, when deer must rely on a wider variety of plants. Palatability also varies among specific aster species and cultivars. For instance, New England Aster (Symphyotrichum novae-angliae) is known to be tougher and more consistently avoided than the White Wood Aster (Eurybia divaricata), which may be more susceptible to browsing.
Why Deer Choose or Reject Plants
A deer’s decision to consume or reject a plant is based on the interplay of physical texture and chemical composition. Plants, including asters, have evolved specific mechanisms to deter herbivores. These defenses make the foliage less appealing or mildly toxic, prompting deer to seek softer, more palatable options.
Asters possess physical defenses, notably the hairy or fuzzy texture of their stems and leaves, known as pubescence. This dense covering makes the plant physically difficult to chew and unpleasant to the touch. Many species, particularly the New England Aster, also develop tough, fibrous stems that offer little nutritional reward for the effort required to process them.
Beyond texture, asters employ specialized secondary metabolites that function as internal chemical deterrents. These compounds include terpenoids, saponins, and phenolic compounds, often concentrated in the leaves. Sesquiterpene lactones, a type of terpenoid, impart a bitter taste to the foliage. Phenolic compounds like tannins can also bind to proteins, reducing the nutritional value and making the plant difficult for the deer to digest.
Protecting Asters and Other Landscape Plants
For gardeners in areas with high deer populations, relying solely on a plant’s natural resistance is often not enough to prevent damage. The most effective strategy involves establishing physical barriers.
Physical Barriers
A permanent fence should stand at least 6.5 to 8 feet high, as deer are capable of jumping lower obstacles when motivated by hunger. For protecting smaller, individual plantings of asters, temporary netting or small cages can be used during the vulnerable late-season months.
Repellents and Maintenance
Using commercial repellents is another viable option. These products, which often contain offensive ingredients like capsaicin, putrefied eggs, or predator urine, require consistent maintenance. To prevent deer from becoming accustomed to a single scent or taste, repellents should be reapplied regularly and rotated with different formulations throughout the season.
Strategic Placement
Strategic placement in the garden can also help reduce the likelihood of browsing. Deer are typically wary of human activity, so planting asters close to a house, deck, or frequently used pathway may deter them. Companion planting with highly fragrant, deer-avoided plants, such as lavender, Russian sage, or yarrow, can also create a natural buffer.