The elephant ear plant, also called taro or by its Latin name, Colocasia, are a genus of water-loving tropical plants with a distinctive elongated heart-shaped leaf which strongly resemble the ear of an elephant. Most species sold in commercial nurseries are strictly tender plants, meaning they will overwinter outdoors only in the warmest climates--USDA zone 9 and south. However, some cultivars are hardy as far north as zone 7, with heavy mulching and careful attention to site placement.
Taro (Colocasia esculenta) is the most commonly available type of elephant ear from most nurseries. The species is recognizable by its 12- to 24-inch leaves which grow on stems between 2 and 3 feet long, though the overall height of the plant itself can reach 5 to 7 feet. From a distance, plants appear to have a mounding habit, with leaves overlapping each other and cascading downward toward the ground, completely obscuring the plant's base.
Care and Cultivation
Elephant ear prefers very moist sites. When grown in a pot, the plant can be placed in up to 12 inches of standing water up to the rim of the pot. With adequate water, elephant ear will grow in full sun, though typically the plant prefers partly shaded sites, especially in the hot afternoon hours. Elephant ears are heavy feeders and should be supplied with a slow-release fertilizer throughout the growing season. In most climates, the plant will not survive the winter in the ground; the root and corm should be lifted before first frost and either grown indoors in a pot or stored in dried peat moss in a cool, dark location.
Many different cultivars have been developed recently for overall size or colored leaves, including 'Lime Zinger,' a 6-foot tall plant with chartreuse green leaves, 'Illustris,' a black-and-green variegated variety, and 'Black Magic,' a deep purple type. A different species of elephant ear, Xanthosoma sagittifolium, is sometimes available in Florida. In all, over 200 named varieties exist.
Elephant ear has no major pests. However, in areas where it is not killed back by frost in the winter, Colocasia itself is considered to be a pest; in some areas of Florida it has escaped cultivation and is now crowding out native wetland species in areas where it becomes established. Warm-climate gardeners should site this plant with care.
All parts of the raw, uncooked elephant ear are poisonous when ingested. The responsible compound, calcium oxalate, causes stomach irritation and extreme pain in the mouth when the plant is eaten, and sensitive individuals may develop a rash when they come in contact with plant juices. However, the cooked roots of the plant are similar in flavor and texture to the potato, and are used as such in many tropical areas. The poi dish of Hawaii, for instance, is made from fermented and mashed taro tubers.