Tomatillo plants, cousins to tomatoes and peppers in the nightshade family (Solanaceae), are generally resistant to deer browsing. They are not a preferred food source, so initial concerns about deer eating them are often unwarranted. Deer typically avoid tomatillos due to protective chemical compounds and unique physical structures. Understanding why deer avoid these plants, and the specific circumstances that change this behavior, can help protect your harvest.
Tomatillos: A Low-Priority Food Source for Deer
The primary reason deer bypass tomatillo plants is the presence of natural chemical defenses. Like other members of the nightshade family, tomatillos contain toxic compounds known as glycoalkaloids, such as solanine, concentrated in the leaves, stems, and unripened fruit. These compounds are naturally bitter and can cause stomach distress or illness in large mammals, making the plant unpalatable and a deterrent to foraging deer.
Deer have a strong sense of smell and taste, allowing them to detect the bitter flavor and chemical signature of these toxic substances. This signals that the plant should be avoided. The alkaloids serve as the plant’s internal defense system against most herbivores.
Beyond the chemical deterrents, the fruit possesses a notable physical defense: the papery husk, or calyx. This structure completely encases the developing fruit, acting as a physical barrier that must be breached before the fruit can be accessed.
The fruit is further protected by a sticky coating that adheres to the skin once the husk is removed. This waxy layer contributes to the fruit’s unappealing nature for browsing animals. The combination of bitter foliage and protective layers means deer rarely browse the plant heavily, instead choosing more palatable food sources.
Factors That Increase Tomatillo Vulnerability
Tomatillos are not immune to deer damage under certain environmental pressures, even though they are generally avoided. Deer are opportunistic foragers and will ignore their natural aversion when faced with extreme hunger or a lack of preferred forage. Periods of prolonged drought or late winter scarcity can force deer to consume plants they would normally leave alone.
A high population density of deer can lead to overgrazing, depleting their usual food supply. In these conditions, deer will consume less palatable plants like tomatillos simply for survival. Young plants are especially vulnerable, as they may not have fully developed the high concentration of defensive alkaloids found in mature foliage.
The most vulnerable stage is when the plants are small and tender, such as seedlings or new growth, which are easier to consume. The fruit’s high water content can also make it attractive to deer during dry periods when water sources are scarce. If a deer samples a plant and finds it tolerable, it may return to browse more extensively.
Effective Methods for Deterring Deer
For gardeners whose tomatillos are under threat, a layered approach using both physical and chemical methods offers the best protection. The most reliable solution is a physical barrier, such as an enclosure built with simple netting or wire mesh. Since deer are hesitant to enter small, confined areas, a fence as low as four feet can be an effective deterrent for small patches.
Individual plants can be protected by installing sturdy tomato cages or stakes wrapped with fine mesh, preventing deer from accessing the foliage and fruit. For chemical deterrence, commercial repellents using putrescent egg solids, essential oils, or strong scents can be applied directly to the foliage. These products work by creating an unpleasant smell or taste.
A strong-scented bar of soap can be hung from stakes around the perimeter to mask the plant’s scent in small gardens. However, deer can become accustomed to a consistent smell, so switching between scent-based and taste-based repellents every few weeks is necessary to maintain effectiveness. Planting pungent herbs like rosemary or garlic near the tomatillos can also help naturally mask their scent and discourage browsing.