Colocasia esculenta, also called elephant ear plant, provides a tropical feel to the garden. Large leaves up to four feet long, in a range of foliage colors, make this plant an impressive specimen. Although native to the warmer parts of Asia, elephant ears will grow in much of the United States. Colocasia can even be grown in cold areas with protection.
Elephant ears require very rich soil and ample water. The planting bed should be made up of composted steer or chicken manure for maximum nitrogen. Colocasias are very heavy feeders, and richer the soil the larger the plant will become. Although they will grow in full sun, leaves tend to develop larger size in partial shade. Growing from a large bulb, some types will also develop a more fibrous root system if grown in a wet area or a bog garden.
Despite their heavy summer water needs, elephant ear dislikes winter moisture in cold areas. The combination of frigid weather and waterlogged soil can lead to rot. Plant in well drained soil or grow it in a large pot.
Most colocasias are hardy to growing zones 7 through 10. In colder areas, they can be dug up and stored indoors for the winter. Bulbs can be stored in lightly moistened peat moss. Fibrous rooted elephant ears should be potted up and placed in a cool area that does not freeze. Water only enough over the winter to keep the plant moist. Too much water or heat can cause it to break dormancy early.
Colocasias have a number of varieties with different sizes and striking foliage coloration.
Colocasia esculenta 'Black magic', 'Black Runner', and 'Diamond Head' are all black leaved cultivars. 'Diamond Head' has extremely glossy leaves, while 'Black Magic' and 'Black Runner' are matte. These varieties will grow four to six feet tall.
Colocasia esculenta 'Lime Aid', 'Mojito' and 'Nancy's Revenge' are variegated. Each variety has unique variegation, ranging from pale yellow leaf centers in the case of 'Nancy's Revenge' to wild random splashes of white, green and yellow for 'Mojito'. They will reach four to six feet tall, and exhibit their best color in areas with afternoon shade.
The largest colocasia is 'Jack's Giant,' which can reach eight feet in height and spread. Give this plant plenty of room. This variety has very large leaves, up to four feet long and nearly as wide at the apex.
Even though most colocasias are hardy in growing zones 8 through 10, cold tolerance can change drastically depending on cultural techniques. Cold and wet winter weather will do in plants rated as hardy unless they are in well drained soil. Overwinter them in the ground in marginal climates by placing a layer of mulch at least a foot thick over the crown of the plant after the foliage dies down in fall. For extra protection, this can be followed by a layer of plastic to repel moisture and a burlap covering to prevent the plastic from overheating.
Colocasias lend themselves to a tropical style in the garden. They can be planted with bananas, hostas and cannas for an exotic look. Grow elephant ears with other water loving plants, mixing foliage textures and colors for added interest. The larger types will take up quite a bit of space, and will grow wider with age, so be sure to locate them where they can spread comfortably. Smaller cultivars can be grown in pots, mixed with brightly colored annuals.
Colocasia is considered a food plant in some areas of the world, however the leaves are toxic. They contain calcium oxalate, which causes a burning sensation upon ingestion. Handling the foliage can produce allergic dermatitis as well. Keep children and pets away from this plant.