The large, dramatic, heart-shaped leaves of the tropical tuberous plants known as elephant ears shelter a hidden world of insect life from birds and other predators. These colourful, highly decorative plants feature violet-black, mottled burgundy or solid green foliage, and some have prominent, pale yellow veins and deep burgundy stems.
Although the moniker elephant ear is broadly used to describe many different tropical plants with heart-shaped leaves—including caladiums—it’s typically the common name for Alocasia, Colocasia and Xanthosoma. Despite much confusion in the world of botany about the differences between these three genera, it’s enough to know they all belong to the Arum family.
However, there are some important cultural differences among them. Alocasia, for example, should be kept evenly moist but not overly wet; it doesn’t grow well when submerged in water, as do other types of elephant ears. Colocasia, on the other hand, should be kept continually moist and can be grown submerged in a shallow pond up to 15 centimetres deep. Xanthosoma, meanwhile, prefers consistent moisture, but will tolerate occasional dry periods. Yet, all three types of elephant ears adapt well to containers, where they grow densely and vigorously, even with limited root space.
- Full sun (for better foliage colour) to full shade; green foliage types tolerate more sun than do burgundy ones.
- Plant tubers indoors in a pot in early spring so the growing tip sits barely above the soil. Gradually move them outdoors after all danger of frost has passed and nighttime temperatures remain above 7ºC.
- In the garden, plant in rich, organic, slightly acidic compost or garden soil with good drainage.
- To conserve moisture, mulch planted corms or tubers with shredded bark or small wood chips, about five centimetres deep.
- Fertilize monthly with a 20-20-20 formula during the growing season; these plants are heavy feeders.
- Protect from strong winds; the sail-like leaves grow on weak stems, which are prone to damage.
- Monitor for mites during hot, dry summer weather or if overwintered indoors as houseplants. Control infestations with a half-strength insecticidal soap-and-water solution sprayed on both sides of the leaves twice weekly. Test a small area first to see if the plant tolerates the spray.
- Divide in spring using a sturdy knife. Remove corms and tubers and replant the largest ones; if these are relatively small, group two or three together, pointy end upward (if in doubt, position it sideways).
- Overwinter when temperatures drop below 10ºC and leaves start to yellow; dig up tubers and trim off foliage, leaving a short stalk. Cover with peat moss or vermiculite and store in an uncovered cardboard box (for container-grown tubers, trim off the foliage and leave them in the container). Place in a cool, dark basement or garage where temperatures remain above freezing.
- Colocasia and Xanthosoma may be overwintered outdoors in Zone 7 and up; reduce watering to keep plants only slightly moist. Mulch to a depth of between five and 10 centimetres for extra protection. New spring growth will begin when the soil warms up.