The keys to successfully winterizing elephant ear (Colocasia esculenta) are the temperature the bulb (which are actually corms not bulbs) is stored at, complete darkness and the choice of packing material. The bulbs must not freeze, yet the temperature can not rise to the point when the bulb puts out new growth. Both scenarios may cause the elephant ear bulb to die. To keep the bulb dormant make sure you store it in total darkness. Indirect light, even if it is weak, may cause the bulb to sprout. Pack the bulb in a moisture retentive material like sawdust to prevent the bulb from drying out.
Wait until after the first light frost when the elephant ear's foliage has started to brown to winterize the bulb. Allowing the foliage to brown is important as the dying leaves tell the bulb to go dormant.
Cut foliage back to 5 to 6 inches.
Dig the elephant ear bulb up.
Wash off all the soil adhering to the bulb.
Remove the roots or rootlets (thin, hairlike roots) using sharp scissors or pruning shears and cut the remaining foliage back to 1 to 2 inches high.
Dry or cure the elephant ear bulb by placing it in a dry spot out of direct sunlight and wind with a temperature between 60 and 70 degrees F. Be sure that the spot you choose is well ventilated. Leave the bulb to cure for one to three days. Wait until the bulb is dry to the touch before proceeding.
Write the cultivar name on the side of the elephant ear bulb with a permanent maker if you grow more than one type of elephant ear.
Place a 2- to 3-inch layer of peat moss or sawdust on the bottom of the plastic crate; the crate should have ventilated sides. Place the elephant ear bulb in the crate. Cover and surround the bulb with 2 to 3 inches of peat moss or sawdust. The bulbs should not touch one another, and no part of the bulb should be visible.
Store elephant ear bulbs in a dark location with a temperature between 40 to 50 degrees F.
Check your elephant ear bulbs monthly. Discard any bulbs that have rotted and remove the peat moss or sawdust that was touching the bulb. If the bulbs appear shriveled, mist them thoroughly with water. Allow them to air dry for five to six hours or until the bulb is dry to the touch. Replace the bulb in the crate.
Pot up elephant ear bulbs eight weeks before your last frost date. Doing this will give your bulb ample time to germinate and produce leaves before you replant it in the garden.