Mammoth elephant ear, also known by its Latin name, Caladium, is a perennial plant valued for its ease of care and large, ornamental foliage. An elephant ear is classified as mammoth if the tuber is at least 3 1/2 inches in length. The leaves of the plant resemble the ear of an actual elephant, hence the common name. Native to Central and South America, mammoth elephant ears thrive in USDA hardiness zones 9 through 12, though they can easily be grown in colder regions with the proper winter care.
Plant mammoth elephant ears during mid-spring once the soil temperature averages 70 F. Choose a planting site that receives partial sunlight and consists of well-drained, moist, fertile soil. Apply a 2-inch layer of pine bark mulch over the planting site and use a garden tiller to work it into the soil prior to planting.
Dig a hole at the planting site about 2 inches deep and place a mammoth elephant ear tuber inside. Cover the tuber gently with soil and water the soil lightly to collapse any air pockets and allow the moisture to come in contact with the tuber. Space mammoth elephant ears at least 12 inches apart to allow enough room for mature growth.
Spread a 2- to 3-inch layer of organic mulch over the soil surrounding mammoth elephant ears to keep the soil cool, conserve moisture and deter weeds. Replenish the mulch as necessary throughout the growing season to keep it at least 2 inches thick.
Water mammoth elephant ears once per week during spring, summer and fall to keep the soil from drying out completely. Apply water directly to the soil instead of watering overhead, as moist leaves are more susceptible to pests and fungal diseases.
Feed once every four to six weeks using a low-nitrogen 5-10-10 NPK fertilizer. Water both before and after feeding to prevent root burn and release the nutrients into the soil. Apply at the rate described by the fertilizer manufacturer's instructions for the best results.
Dig up mammoth elephant ear tubers during fall, prior to the first frost of the season, if you live in USDA hardiness zones 3 through 8, where winter frost is a danger. Store the tubers in a box filled with peat moss at a temperature of 45 F to 55 F throughout winter. Replant the tubers outdoors the following spring.