Deer browsing is a common challenge for gardeners, often causing significant damage to vegetable plots. Potato plants are generally considered resistant to deer, meaning they are not a preferred food source, but they are not entirely immune to browsing pressure. This natural defense offers protection, yet it does not eliminate the need for vigilance, especially in areas with high deer populations or during food scarcity.
How Potato Plants Deter Deer
The primary reason deer avoid potato plants is the presence of natural chemical compounds called glycoalkaloids, mainly alpha-solanine and alpha-chaconine, which act as the plant’s defense system. These compounds occur in the leaves, stems, flowers, and any green parts of the potato, including tubers exposed to light. They give the foliage a bitter taste and make it mildly toxic. The concentration of these glycoalkaloids is highest in the leaves and stems, the parts a foraging deer would typically consume.
Deer are sensitive to the unpleasant taste and the potential for gastrointestinal distress caused by ingesting these compounds, leading them to bypass potato plants in favor of more palatable vegetation. The plant increases its production of these compounds when under stress, such as from pests or herbivores, further intensifying the natural deterrent. However, this resistance is not absolute; deer may still browse on potato foliage if they are extremely hungry, if other food sources are scarce, or if they are young animals.
Protecting Potato Plants from Hungry Deer
Although potato plants possess a natural defense, relying solely on this can lead to crop damage, making human-implemented strategies necessary for complete protection. Physical barriers are consistently the most effective method to prevent deer access to a garden space. A deer-proof fence needs to be at least 8 feet tall, as deer are capable jumpers, and should be secured to the ground to prevent crawling underneath. For smaller plots, a shorter fence angled outward at a 45-degree angle can confuse the deer, making the jump seem more difficult.
Chemical deterrents offer another layer of protection, working primarily on the deer’s sense of smell or taste. Repellents containing putrescent egg solids or garlic are widely used, but they must be applied consistently and reapplied after rain to maintain effectiveness. Rotating different types of repellents is recommended, as deer can quickly become accustomed to a single scent or taste, reducing long-term efficacy.
Motion-activated sprinklers and noisemakers can serve as temporary deterrents by startling deer with a sudden burst of water or sound. These methods exploit the deer’s cautious nature, but they are generally less reliable than physical fencing over an entire growing season. Interplanting potatoes with highly aromatic, deer-resistant herbs like garlic or lavender can also be used as a minor deterrent.
Related Nightshade Plants and Deer
Potato plants belong to the Solanaceae family, commonly known as the nightshade family, which includes garden staples like tomatoes, peppers, and eggplant. Like potatoes, these related plants also produce glycoalkaloids and similar defensive compounds, contributing to their reputation as generally deer-resistant. The concentration and specific type of compound, however, vary among the different plants.
Tomato leaves and stems contain tomatine, a glycoalkaloid similar to solanine, which gives them a bitter taste and deters deer from browsing the foliage. The leaves and stems of pepper and eggplant plants also contain these defensive chemicals. While the foliage of these nightshades is typically avoided, deer have been known to eat the fruit of tomatoes and peppers, especially when other food is scarce. This browsing behavior suggests that deer distinguish between the plant’s toxic foliage and the less-protected, edible fruit.