“Black Magic” elephant ears (Colocasia esculenta “Black Magic”), and other purple cultivars of taro, are the only crops that grow from “bulbs” that produce big purple leaves. Bulb is a misnomer when explaining elephant ears, the ornamental type of taro. What looks like a bulb is technically a corm. Showy elephant Coast make a good addition to the border of a backyard pond in a water garden.
Bulbs vs. Corms
Although nurseries and garden centres frequently market elephant ear “bulbs,” they are actually selling corms. Like true bulbs, corms store nutrients for the plant to use while it is dormant. The corms of decorative taro cultivars might be weigh 1 to 2 pounds while these cultivated for food might weigh up to 8 lbs. “Jet Black Wonder” (Colocasia esculenta “Jack Black Wonder”) and “Jet Black Gold” (Colocasia esculenta “Jet Black Gold”) are other decorative taro cultivars with big purple leaves.
Elephant Ear Leaves
Elephant ears grow from 3 to 6 feet tall. Their heart-shaped leaves grow from 12 to 30 inches long and appear like taro leaves only they are purple, not green. Elephant ears are dark purple to almost black and are spongy, full of air spaces. They have small, netted veins between larger, parallel lateral veins and deep purple proportions.
In Warm Climates
Elephant ears and other taro cultivars grow as perennials in U.S. Department of Agriculture plant hardiness zones 8 through 11. Elephant ears obviously form large colonies along ditches, canals, ponds, streams, bogs and swamps. Space them 18 to 24 inches apart to provide them with room to spread. They need moist soil and can be grown in water 12 inches deep. The crops need from three to five hours of full sun daily.
At Cold Climates
Frost will kill the elephant ear stems and leaves but the bulb will survive. When this occurs, you can grow it as a summer annual. Dig the corms up and store them over winter in wood shavings or dry peat in a space where temperatures don’t fall below 45 degrees Fahrenheit. In late winter or early spring, plant the corms in one single- or even 2-gallon pots, water them once and keep them indoors or in a greenhouse. Don’t water them again till they make new leaves. When all danger of frost has passed, then transplant them outdoors.