Spirea, a genus of flowering deciduous shrubs (Spiraea), is a widely popular ornamental plant used in diverse landscape settings. Gardeners in areas with high deer populations often seek plants that can withstand browsing pressure, and Spirea is frequently suggested as a suitable choice. Horticultural experts and wildlife management organizations agree that this shrub exhibits a high degree of natural resistance to deer damage. This characteristic makes it a common recommendation for landscapes where other shrubs might be routinely consumed.
Spirea’s Classification as Deer Resistant
Spirea is categorized by agricultural extension services and university resources as a plant “rarely damaged” by deer. This classification means that deer generally avoid the plant, even when more desirable food sources are limited. The plant’s natural defense mechanisms are primarily responsible for this low palatability, making it a reliable choice for foundation plantings.
Deer often base their feeding decisions on the texture and chemical composition of the available foliage. Spirea leaves possess characteristics that make them less appealing, such as a slightly coarse texture or a subtle, bitter flavor. This bitterness is attributed to low concentrations of secondary metabolites, which signal to the animal that the plant is not a preferred food source. Under normal circumstances, a browsing deer will select a softer, more palatable plant nearby before resorting to Spirea.
Why Deer Palatability Varies
Despite the plant’s inherent defenses, Spirea’s resistance is not absolute and can be overridden by external conditions. The most significant variable is the level of localized deer pressure, often driven by environmental scarcity or population density. If winter conditions are severe or a prolonged drought occurs, deer will consume almost any available vegetation to meet their caloric needs.
Under high-pressure scenarios, the slight bitterness or coarse texture of Spirea is less of a deterrent than the necessity of finding food. The maturity of the plant also significantly influences its appeal. Younger Spirea plants or new spring growth are notably more susceptible to browsing damage because this tender foliage contains higher water content and is softer.
New growth is often browsed first because it represents an easier, more digestible meal than the tougher, older parts of the shrub. Different cultivars within the Spiraea genus may also exhibit minor variations in palatability.
Strategies for Protecting Spirea
When environmental factors force deer to browse Spirea, gardeners must employ proactive protection strategies. Repellent sprays are a common method, working by coating the foliage with a distasteful or foul-smelling substance. Effective repellents often contain active ingredients like putrescent egg solids, which deter by smell, or capsaicin, which creates an unpleasant taste.
To maintain long-term effectiveness, it is beneficial to rotate the type of repellent used, switching between odor-based and taste-based products. Deer can become habituated to a single deterrent over time, making rotation necessary for sustained management. For newly planted or small shrubs, temporary physical barriers, such as mesh cages or netting, offer the most reliable immediate protection. Strategically placing Spirea near plants that deer strongly avoid, such as highly fragrant herbs or toxic perennials, can also reduce browsing likelihood.