Yes, oleander (Nerium oleander) is considered highly deer resistant. The primary reason for this resistance lies in the plant's potent toxicity. Oleander contains a suite of cardiac glycosides, including oleandrin and nerioside, which are present in all parts of the plant: leaves, stems, flowers, and even the sap. These compounds are extremely bitter and cause severe irritation to the mucous membranes of mammals. When a deer samples an oleander, it experiences an almost immediate burning sensation in the mouth and throat. This powerful negative feedback effectively teaches the animal to avoid the plant entirely in the future. From a survival perspective, deer are opportunistic browsers that instinctively avoid known toxins to prevent illness, making oleander a reliable choice for landscapes with deer pressure.
Beyond its chemical defenses, the oleander's physical attributes further contribute to its deer resistance. The plant possesses tough, leathery leaves that are not palatable or easily digested. Deer generally prefer tender, soft foliage, and the texture of oleander leaves is unappealing to them. Furthermore, the sap is a milky, sticky latex that can be irritating, providing another layer of protection. While the flowers are fragrant to humans, their scent does not appear to be a major attractant for deer as a food source. These combined physical traits—tough foliage, irritating sap, and bitter taste—create a multi-faceted defense system that makes oleander an unpalatable and undesirable meal for deer.
For gardeners in deer-prone areas of the US, oleander serves as an excellent foundational or screening plant. It is a fast-growing, drought-tolerant evergreen shrub that thrives in warm climates (USDA zones 8-11), making it particularly popular in Southern and Southwestern landscapes. It can be used effectively as a hedge, windbreak, or a standalone specimen to create a deer-resistant barrier. However, its extreme toxicity requires careful consideration. It should not be planted in areas accessible to children or pets who might be tempted to chew on it. All pruning clippings must be disposed of immediately and safely, and one should always wear gloves when handling the plant to avoid skin irritation from the sap.
While oleander is reliably deer-resistant across its growing range, its performance can be influenced by extreme environmental factors. In times of severe drought or food scarcity, a desperate deer might nibble on plants it would normally avoid. However, such instances are rare for oleander due to the strength of its toxins. To create a truly resilient landscape, it is advisable to complement oleander with other deer-resistant plants. Good companions include Russian sage (Perovskia atriplicifolia), lavender (Lavandula), salvia, lantana, and ornamental grasses. This strategy, known as "deer-resistant landscaping," uses a palette of unappetizing plants to protect the entire garden, reducing the likelihood that deer will even venture into the area to test the oleander.
