For vividly colored, dramatic foliage, few plants can top the caladium (Caladium spp.), which thrives in shade and is renowned for its large, exotically colored leaves. The most commonly grown variety is a South American native (Caladium bicolor) that's usually just called a caladium and sometimes called angel wings because of the shape of its leaves. It's simple to grow when given some shade and basic care, but it is a frost-sensitive plant that needs special attention at the end of the growing season to help it survive winter so it can regrow the following spring.
A caladium grows from a potato-shaped bulb called a tuber, which survives outdoors year-round in U.S. Department of Agriculture plant hardiness zones 9 through 10, where winter temperatures rarely drop below freezing for more than a few hours. You can grow this plant in any part of the United States, though, if you take proper care of the tuber as winter approaches.
A caladium dies back naturally as the growing season ends; it loses its foliage and enters dormancy as autumn approaches. If you live within USDA zones 9 through 10 and winters remain mild, then you can leave caladium tubers in the ground during winter if their outdoor garden spot is well-drained and isn't normally disturbed during cold weather. If you plan to keep them in the ground, then stop watering and fertilizing them as fall approaches, and mark the location of each plant with a small stake labeled with the plant's variety. It's also a good idea to add a few inches of organic mulch or a few pine boughs over the planted area to protect the tubers in case a cold snap occurs.
If your location's winters are mild but your caladium planting site tends to stay soggy during winter, then the caladium tubers might rot. If soil sogginess is an issue during winter, or if you want to work the garden bed for other spring plants or relocate the caladiums the next spring, then it's best to dig up the tubers and store them over winter.
In areas outside of USDA zones 9 through 10, digging up caladium tubers before winter is necessary to save the plants for the following year. Dig up the plants when their foliage has yellowed and wilted but is still attached -- making it easier to locate the tubers.
Digging and Drying
Use a fork or shovel to dig up and lift caladium tubers, doing it gently so that you don't injure the bulbs. Dig a bit outside the planted area first to loosen the soil. Then gradually work your way into the caladium bed. Lift each tuber by its dried foliage, and brush off the dry soil. If the soil is moist, put the tubers in a warm spot for a few hours to allow the soil to dry, and then brush it off.
Before final storage, tubers need 10 to 14 days to dry; you'll know they're ready when their attached foliage falls off readily, leaving behind dry scars on the tubers. Brush off all remaining soil, and then check each tuber for moist cuts or other damage, and discard such tubers. Dry, healed scars on a tuber are not a problem and shouldn't interfere with the plant's survival.
Caladiums growing in pots die back in fall, like caladiums in the ground. You can either leave them in the pots, moving them indoors for winter, or remove them from the containers and store them as you would garden-grown caladiums. If you leave them potted, withhold water from them during the winter months.
Store the dry tubers in breathable bags; old nylon stockings, mesh onion bags or paper sacks work well. It's helpful to group the tubers by variety in individual bags, dropping a paper label into each bag or adding a tag to indicate the cultivar. You can also store the tubers in a cardboard box filled with peat moss, but space the tubers so they don't touch to help prevent rotting.
Store the tubers in a dry location that stays about 70 degrees Fahrenheit during winter; an unused closet or a heated basement is a suitable place. Check the tubers every few weeks, discarding all that have darkened, soft spots, which indicate rot.