Unfortunately, the common trade name “Elephant Ear Plant” has been used and abused so tirelessly that, standing alone, it is absolutely impossible to know which plant is being discussed.
Moreover, this confusion is perpetuated by nursery stock with labeling that fails to list a scientific name, at least to genus. One can therefore go home with an elephant ear and have little idea as to how it should be maintained.
In fact, this colorful moniker is often associated with no less than four distinctive genera of herbaceous perennial plants. And while they all share some characteristics, such as being toxic, they do vary in their husbandry requirements such that a separate discussion for each is useful to grow and care for them properly. For example, things like sun exposure, cold hardiness, soil type and moisture, and mature size are not standard when talking about elephant ears.
Please follow along as we break down each type of the four so-called elephant ear plants and provide basic growing instructions.
1) Elephant Ear Plants in the Genus Colocasia
Commonly known as “taro” in many areas of the world (especially Asia) where it’s grown for its carbohydrate-rich corm, the genus Colocasia enjoys wide popularity as a food crop and a bold ornamental plant. There are just over a dozen species of Colocasia named to date, with several more likely to be announced in the near future. Colocasia esculenta is a particularly widely grown species used for food production.
Given Colocasia’s cosmopolitan distribution and the many thousands of years that it’s been under cultivation, its origin is a subject of debate. Nevertheless, it is believed that it may have originated Asia, most likely in lowland Malaysia. The corm of this plant is edible, as is the rest of the plant. However, its tissues are laden with calcium oxalate crystals – a potent plant toxin that can cause an acute reaction at very low doses. Symptoms of mild poisoning include chocking and burning/swelling in the mouth and throat, which could last for weeks. Thorough cooking is necessary to deactivate this toxin, although Colocasia varieties grown specifically for food are likely to have much less calcium oxalate to start with.
There are many cultivars of this type of elephant ear plant, but most are very large specimens and some species, such as the Thailand “Giant” strain, can grow over 6 feet high and push massive leaves that may in fact approach elephant size ears! Needless to say, a plant of this stature is best shown off growing outdoors or in a greenhouse where it can reach full size; however, it can be potted and kept indoors in very bright light, where it will remain much more manageable while still making a spectacular and large indoor plant.
An important consideration to bear in mind when growing this type of elephant ear is that they thrive in moisture. Indeed, their affinity for water makes them an ideal marginal plant around ponds or other water sources, and they are often grown partially submerged in water. Consequently, if grown in the ground or in a large planter, make sure that the soil remains uniformly moist. They are also notorious for being very heavy feeders, so keep them well fertilized with a balanced formula throughout the growing season if you want to enjoy this plant in all its glory. They prefer soil that is well-draining and neutral to slightly acidic.
As you might guess given their distribution among equatorial zones, this species appreciates high humidity. And while it can tolerate dryer conditions, this does make it highly susceptible to spider mites. Diligent monitoring of plants grown in drier climates should be performed to avoid a full-blown mite infestation that could prove difficult to control. Colocasia generally do best and reach their most attractive proportions in full sun, but can tolerate partial to full shade outdoors and still thrive. Indeed, locating specimens in shade is preferable in regions that experience lots of heat and low humidity during the growing season.
In fall, shortening day length will gradually trigger a cessation and die back of vegetative and root mass in favor of flowers and corm formation. Depending on the variety, Colocasia may be overwintered outdoors in regions as cold as USDA zone 7, but always confirm before purchasing. If overwintering in zones colder than 8a, it is advised to bury the corm in mulch up to a depth of 6 inches. If the corm successfully overwinters, you should see new growth emerge in spring. In zones below 7, growers should trim the remaining leaves and roots from the corms and remove them to overwinter indoors buried in mulch; they may be stored anywhere temperatures remain above freezing, and can be replanted in spring after the danger of frost passes. Alternatively, the corm can be treated as a houseplant and given bright indirect light in a cool location. Take care not to fertilize or water excessively during this time as the plant’s growth will be very slow.
2) Elephant Ear Plants in the Genus Alocasia
The genus Alocasia is a plant collector’s dream, currently holding about 79 species, not including various hybrids. They are native to southern Asia and Eastern Australia, but have long been cultivated in the South Pacific and elsewhere for food. Their rich corms are edible like those produced by Colocasia described above. And like Colocasia, the tissues of Alocasia contain toxic calcium oxalate as a means of defense against herbivorous animals.
The breadth and variety of this very interesting genus makes generalization difficult. For example, Alocasia x amazonica is a striking small to moderate sized specimen that boasts gorgeous contrasting dark foliage and whitish veins. This is one of the most highly-celebrated members of the genus for cultivation as an indoor plant, given its exotic look and relatively straightforward care. While not as easy as the typical houseplant, A. x amazonica has a fairly short list of requirements – provide them very bright indirect light or filtered direct light; maintain warm temperatures; give them high humidity; and grow them in quickly draining soil that is always kept uniformly moist.
In stark contrast to the comparatively dainty A. x amazonica stands Alocasia macrorrhizos (sometimes denoted A. macrorrhiza), which also goes by the names “elephant ear taro,” “giant taro,” and “ape.” Unlike the horizontal or drooping orientation of most elephant ear plants, this behemoth proudly stands with its massive leaves pointed upwards toward the sky. This is a true mountain of an herbaceous plant, and under ideal growing conditions the “Borneo Giant” strain can throw up two to three meter long stalks supporting one meter long leaves for a total height of 10-12 feet from base to leaf tips! Recent taxonomic study of the giant elephant ear taro using DNA sequencing places the origin of A. macrorrhizos in the Philippines.
If you seek maximum size and rapid growth, provide the giant elephant ear plant with full sun. However, it can also do fairly well in partial shade but may not reach gargantuan size. It also enjoys warm temperatures, high humidity and needs lots of water throughout the growing season. Avoid letting the soil go dry and be sure to feed well. Enriching the soil with high amounts of organic matter, such as steer manure, is recommended.
Like most elephant ears, they are highly vulnerable to mite attack in arid regions, which can be mitigated to some degree with frequent misting or spraying.
This species will not tolerate cold winters, and is generally less cold-hardy than Colocasia. For growers in USDA zones 8 and below, it is advisable to dig up the corms in fall around the first frost and overwinter indoors.
Despite its towering stature and almost frightening growth rate in ideal conditions outdoors, the giant elephant ear can be tamed in a container, and makes an outstanding, large indoor plant. It can grow 5 feet tall (or more) if provided with enough bright indirect/direct light and grown in a large pot.
Space permitting, I can hardly think of a more majestic and bold tropical plant for any home or greenhouse.
3) Elephant Ear Plants in the Genus Xanthosoma
Xanthosoma is a roughly 50-member genus that, unlike those discussed previously, is believed to have originated (or at least been first domesticated) in the New World tropics. Overall, they are quite similar in form to Colocasia, and are likewise grown widely for their starchy, edible corm. Although they are cultivated for food in various parts of Asia, the Caribbean, South America, and the Netherlands, they are a particularly important staple in Puerto Rico, Cuba and, more recently, West Africa.
Perhaps the most broadly distributed member of the genus is Xanthosoma sagittifolium, which is primarily grown for food but is also a common collector’s plant.
This is a fast-growing, large species that under ideal conditions can produce leaves up to 4 feet long and 3 feet wide on petioles of a meter in length. The foliage is attractive but relatively understated compared to some elephant ears, and it produces an unremarkable spathe type inflorescence common to the family.
X. sagittifolium does best in warm, very humid environments in strong, filtered light. This species requires continually moist soil that is fast draining and rich with organic matter to reach its full potential.
It can be grown in a large container where will it will make a very large and interesting indoor plant.
Outdoors the corm can survive winters in USDA zones 8 and higher; in colder regions the corm should be dig up and brought indoors until frost danger passes in spring.
In contrast, Xanthosoma ‘Lime Zinger’ is a cultivar that is grown only for its striking bright lime green foliage.
This plant can reach proportions roughly equivalent to X. safittifolium and is in all other husbandry respects likewise similar.
4) Elephant Ear Plants in the Genus Caladium
Unlike all of the other genera above, which are often grown for food, Caladium are strictly ornamental and do not form a corm (the are a tuberous plant). There are roughly a dozen species of Caladium, not including the myriad of popular cultivars available at most large nursery centers. Like Xanthosoma, this is also a New World elephant ear, with its “roots” primarily in South and Central America where they occupy the dappled realm of the forest understory.
Caladium are by far the smallest elephant ear plants discussed here, with an average size of roughly two feet tall by two feet wide. However, what they lack in stature they make up for in color and beauty; these are the showiest of all elephant ears, with varieties coming in a myriad of colors and leaf patterns, including red, white, bright green and pink. For example, the species Caladium lindenii (formerly placed in Xanthosoma) presents a striking arrow-head leaf with a deep green background that’s overlaid with wide, white/cream veins; whereas Caladium bicolor ‘Florida Sweetheart’ has reddish pink leaves fading to green along the margins, and C. bicolor ‘Angel Wings’ has bright white leaves with thin dark veins.
With their striking coloration, small size, and preference for shade or well-filtered direct sunlight, it’s no wonder why this is the most popular indoor elephant ear plant. Further, there are very few rules to abide by when growing these species. Like most of the types discussed above, they crave moisture and humidity. Keep them in a light, neutral to slightly acidic and well-draining soil that is rich in humus and kept continually damp/moist, but not waterlogged. Do not make the mistake of sitting their pots in water as you might a Colocasia!
Light requirements are also easily met, since most Caladium will thrive in full shade outdoors or in bright indirect light or filtered direct light indoors. Keep in mind that bright light is needed for most showy specimens to reach their full color potential. Fertilize as any foliage houseplant, with heavier feeding during the warmer months and when growing in bright light. As with the other elephants ears, all parts of this plant are toxic, therefore care should be taken to avoid accidental ingestion by children or pets.
Perhaps the only real shortcoming of the Caldium is that they are not especially cold hardy, making them ill-suited as an outdoor perennial in many regions of the country. In fact, unless you live in USDA Zone 9 or warmer, you will need to bring this plant indoors for the winter or be prepared to buy new plants each spring. The tubers can be dug up in the fall as nights become cool and, after trimming any remaining leaves/roots, the bulbs can be stored in a moderately-dry peat much in a dark and cool place (around 55F-65F) until spring. Alternatively, the tuber can be transplanted to a container indoors, where the plant may continue to grow (albeit slowly) if kept warm and provided sufficient lighting.
Featured (top) image credit: “Caldium” by Robert S. Donovan CC BY 2.0