Gardeners often wonder if the commonly planted flowers known as geraniums will become a meal for local deer. While the plants are often described as deer-resistant, the likelihood of browsing depends heavily on the specific plant species and the environmental conditions surrounding the deer population.
The Geranium vs. Pelargonium Distinction
The plant most people purchase as an annual “geranium,” often used in window boxes and containers, is botanically classified under the genus Pelargonium. These species, including the popular zonal geraniums, are generally highly avoided by deer. They are considered tender plants, typically grown for only one season in colder climates.
In contrast, the “true geraniums” belong to the genus Geranium and are commonly known as cranesbills. These are hardy perennials that return year after year. Most species within the Geranium genus, such as Geranium macrorrhizum, exhibit strong resistance to browsing. However, some varieties, like Geranium endressii, have been observed to be more frequently grazed.
Both the annual Pelargonium and the perennial Geranium are low on the menu for deer. This general avoidance makes them popular choices for gardeners seeking colorful options in areas with high browsing pressure.
Natural Defenses Against Deer Browsing
Deer tend to avoid both Pelargonium and Geranium species due to their inherent physical and chemical properties. The foliage of many of these plants emits a strong, pungent scent, particularly when the leaves are crushed. This powerful aroma acts as a natural deterrent, as deer rely heavily on their sense of smell to identify palatable food sources.
The leaves of many varieties also possess a bitter taste due to specific chemical compounds, including certain terpenes. This makes the plants unappetizing to grazing animals. The combination of an off-putting odor and an unpleasant flavor discourages deer from consuming the foliage beyond an initial exploratory nibble.
Furthermore, many Pelargonium and Geranium plants have a fuzzy or coarse texture to their leaves. Deer generally prefer plants with smooth, tender leaves that are easy to digest. This rougher texture provides another layer of physical defense that makes the plants less appealing.
When Deer Ignore the Resistance
The designation of “deer-resistant” does not equate to “deer-proof.” The main variable that overrides a deer’s natural aversion is the level of hunger. During periods of extreme food scarcity, such as severe drought or harsh winter months, preferred forage may become unavailable.
When deer are stressed by a lack of food, they become opportunistic feeders and will sample plants they normally avoid. This browsing can lead to damage on even the most strongly scented or bitter-tasting varieties. Different deer populations can also exhibit varied feeding behaviors.
New, tender growth on any plant is more vulnerable to browsing. Young shoots and fresh leaves have not yet fully developed the concentrated bitter compounds or the coarse texture of mature foliage.
Protecting Your Landscape
For gardeners experiencing persistent browsing despite planting resistant species, mitigation strategies can help safeguard the landscape.
Physical Barriers
One effective solution involves implementing physical barriers, which can range from tall fencing to temporary netting around vulnerable plants. Fences need to be at least eight feet high to reliably prevent deer from jumping over them.
Chemical Deterrents
Another common approach is the use of chemical deterrents, which work by creating an unpleasant taste or smell on the plants. These repellents often use ingredients like rotten eggs or putrescent animal proteins to mimic the scent of predators. To maintain effectiveness, it is necessary to rotate between different repellent products so deer do not become acclimated to a single scent or taste.
Companion Planting
Placing geraniums near other highly aromatic plants, a practice known as companion planting, can also amplify the deterrence effect. Plants with strong scents, like lavender, catmint, or certain herbs, can help mask the scent of more palatable plants nearby. This layered defense helps reinforce the existing natural resistance of the foliage.