Nandina domestica, commonly known as Heavenly Bamboo, is a popular ornamental shrub prized for its colorful foliage and bright red berries. Gardeners frequently choose it for its reputation as a low-maintenance plant naturally avoided by foraging wildlife. Horticultural experts agree that Nandina domestica is highly deer-resistant, meaning deer select it only as a last resort. However, no plant is entirely deer-proof, and under certain environmental conditions, even this shrub can be sampled or damaged.
The Direct Answer and Why Deer Avoid Nandina
The reason deer generally leave Nandina domestica alone lies in its defensive chemistry, which makes the plant unpalatable and mildly toxic. All parts of the shrub, including the leaves, stems, and especially the red berries, contain cyanogenic glycosides. These compounds are converted into hydrogen cyanide upon ingestion, acting as a potent natural defense mechanism against herbivores. When a deer attempts to browse the foliage, this chemical makeup results in a bitter taste and a strong, unpleasant odor. This inherent toxicity acts as an immediate deterrent, signaling to the deer that safer food sources are available elsewhere. Consequently, Nandina domestica is classified as a low-priority food item, ensuring it remains mostly untouched.
Factors That Can Overcome Deer Resistance
The deer-resistant classification of Nandina can be overridden by environmental and situational factors. The most common cause for browsing is extreme hunger, particularly during periods of food scarcity like harsh winter months or prolonged droughts. When preferred food sources are exhausted, deer become desperate and may sample plants they would normally avoid. High deer population density also increases browsing pressure, forcing animals to consume less desirable vegetation. Furthermore, the age of the plant material influences browsing. New, tender growth emerging in spring may be sampled because it is softer and temporarily lacks the full concentration of bitter compounds found in mature foliage.
Protecting Nandina from Browsing
If deer begin to browse your Nandina, gardeners must implement active deterrent strategies. Physical barriers are highly effective and provide immediate protection, especially for younger plants. Temporary wire cylinders or netting placed around newly planted shrubs can prevent deer from reaching the vulnerable foliage while the plant establishes its root system.
A multi-layered defense involves utilizing taste and scent-based deer repellents, which must be applied consistently. Repellents containing ingredients like eggs, garlic, or hot pepper extract work by creating an offensive odor and flavor on the leaves. It is advisable to rotate between at least two different commercial repellent variants to prevent deer from becoming habituated. Repellents should be reapplied regularly, often every two to four weeks, and immediately after significant rainfall or overhead watering. Strategic placement of the shrubs can also help, as deer are less likely to venture close to a house or heavily trafficked area. Gardeners should also avoid over-fertilizing Nandina, since the resulting flush of new growth is particularly attractive to deer.