Our other plant passion, second to orchids, is elephant ears. There's just something about them that is spell-binding and yet simplistic. Their rapid growth and ease of culture is welcome compared to slower growing orchids. Elephant ears, or EE's in our age of quick communication, are aroids (Araceae) related to Caladiums, Anthuriums, Philodendrons, Amorphophallus, etc. They do flower, but flowers are insignificant compared to most showy orchids, albeit a little naughty, unless you want to hybridize them. Elephant ears, for our purposes, refers to the genera Alocasia, Colocasia, and Xanthosoma. Colocasias and Xanthosomas are generally grown the same- very bright and wet where temperatures near or slightly below freezing are counteractable by mulching. Alocasias can be split up based on their leaves, plant habit, and cultural preferences with a range of light, temperature, and moisture demands.
Alocasia are old-World elephant ears. They usually grow in bright shade with little to no direct sun. They grow well in Phalaenopsis conditions. Translated: EASY. If you keep them above 65 F, they will continue to grow year-round and will add new leaves continuously. They can add a leaf every week or two under the right conditions. If your temps drop down more in winter, no problem! They'll go dormant when they hit the mid-forties. Simply keep the bulb cool (but avoid freezing!) and dry until spring. Some even plant them in spring after the threat of frost, allow them to grow, then dig up the tubers in fall. Store, replant, repeat. They also produce side tubers fairly freely, so you'll have plants to share.
Most appreciate bright shade with little or no direct sun; however, a few can grow in full to partial sun. They like very freely draining, slightly acidic media like 1:1 sphagnum peat moss: perlite, 1:1:1 sphagnum peat moss: perlite: fine fir bark, a well-draining mix from your garden center, or even straight perlite. For best results, water very well and allow them to almost dry out before watering again (sound familiar paph & phal growers?). They can be kept very wet in summer as long as the mix isn't stale. Fertilize weakly, weekly in summer and monthly in cooler weather.
Alocasia are EXCELLENT candidates for semi-hydroponics!!! They like to be well-hydrated but also have lots of air at the roots= awesome in s/h!
Due to their low light requirements, Alocasias are also great for light gardens.
Alocasia's bold leaves are a target for mites, especially when grown in low humidity conditions. Mites love those gorgeous leaves as much as we do. Use them as an indicator for your collection and have some horticultural oil or soap spray handy to keep the population down. When you water, rinse the leaves off well and let them get rained on once in a while. Summer your elephant ears outside al let the rain and humidity keep them clean. The good thing is they replace leaves quickly.
Alocasias also make great accent plants in orchid displays adding lots of visual, non-floral interest.
Within the Alocasias, we identify four main types: African masks, jewels, other tropicals, and "hardy" greens. Remember that there are always exceptions!
African masks- Well, first, they're not from Africa. Alocasias are generally from tropical and subtropical Asia. Their leaves just resemble African masks in shape and sometimes size. Leaves are generally glossy rich, dark green on top with light green, blue-green, or nearly white veining and can be dark purple or eggplant underneath. Petioles, or leaf stems, may be any shade of green to pink and can be plain or patterned with many different variations on speckling to tiger-stripe markings. In general, African mask Alocasias are small to modestly-sized plants being from one to three feet tall. Alocasia Polly is the classic example of an African mask, and is widely available in home improvement stores. Alocasia sanderiana ‘Nobilis’, Alocasia lowii, Alocasia longiloba, Alocasia x amazonica, Alocasia Purpley, Alocasia Loco, and Alocasia Mark Campbell are other examples of African masks. These should be kept warm. A temperature range of 65-85 F is ideal. In this range, a small seedling can fill a six inch pot in a couple months, adding a leaf or two every week or so. Below 65 F, they will slow their growth dramatically. Below 45 F they may drop their leaves and go dormant. Near or at freezing, they will most definitely drop foliage often after bleeding red pigments (anthocyanins) released from cells by piercing ice crystals off the pointy leaf tips and go dormant. Below freezing, plants may die if the corm suffers frost damage. If corms retain firmness (that is, they don’t get mushy), keep them as they may resprout when favorable conditions return. African masks prefer bright shade with little to no direct sun. Deep shade will cause weak, floppy plants and slow growth. Water them often enough to keep the media evenly moist, although brief drying is fine when temperatures dip below 65 F, and corms may be kept barely moist if the leaves drop. If plants or corms remain wet with constantly cool temperatures, rot may set in. Any traditional, well-draining potting mix is sufficient. Pre-mixes are great, or mix one part sphagnum peat moss with one part perlite, coarse sand, or vermiculite. Fertilize with your favorite balanced fertilizer weakly weekly (less often when temperatures are below 65 F) and flush pots monthly with water only.
Jewels- Some folks group the African mask types with the jewels, but we keep them separate due to appearance and slight cultural differences. Jewel Alocasias are generally compact plants, as are the African masks, but they tend to have round to oval leaves of varying thickness, coloration, and surface texture depending on the species or hybrid parentage. Some of the most fantastic colors and textures are found among the jewel Alocasias from the metallic coppery sheen of Alocasia cuprea to the fuzzy Alocasia reginula 'Black Velvet'. Other jewels include Alocasia nebula, Alocasia infernalis, Alocasia Maharani, Alocasia reversa, Alocasia chaii, Alocasia melo, Alocasia clypeolata ‘Green Shield’, etc. Jewel Alocasias are grown nearly identical to the African masks, but the thicker succulent leaves tell us they can handle drying out briefly between drenching. A loose mix is advisable as well to maintain air at the root zone- supplement your potting media with additional perlite, fine fir bark, and/or coarse sand to improve drainage.
Other tropicals- This group holds “the rest” of the tropical Alocasias. They are usually gorgeous plants, but lack some of the obvious flair the jewels and African masks have. Their elegance is in their leaf structure and subtle coloration and patterning of the leaves and petioles. Grow them the same as the African masks and jewels. Examples include Alocasia zebrina and Alocasia superba with majestic stance and veined green leaves and well-marked petioles, Alocasia lauterbachiana with flamberge sword leaves, , Alocasia princeps ‘Purple Cloak’ with simply stunning deep green and purple, V-shaped leaves, Alocasia macrorhiza (?) ’Borneo Giant’ for its wonderful size, Alocasia brancifolia, Alocasia cuculata, Alocasia ridleyi, Alocasia New Guinea Gold, Alocasia plumbea, Alocasia Stingray...
Hardy greens- These guys aren't always the prettiest, but what they lack in color and pattern, they usually compensate for in size and hardiness. Alocasias in this group tend to range from three feet to six feet in height. As the name implies, they are generally all green, but many have very interesting leaf shapes such as wavy or scalloped margins (edges). And forms with cream variegation are available occasionally. Several representatives from the hardy green Alocasias are good garden candidates to USDA hardiness zone seven or eight with good mulching in fall. Whereas the African masks, jewels, and other tropicals are generally only hardy in zones nine and warmer and may not return from particularly cold winters in those zones. There are also hybrids between hardy green and African mask types that yield plants of intermediate size and decent cold hardiness from the green parentage with improved coloration and interest from the African mask contribution. Alocasia boa, Alocasia gageana ‘California’, Alocasia Hilo Beauty, Alocasia Hilo Bold, Alocasia macrorrhiza, Alocasia macrorrhiza 'Lutea', Alocasia odora, Alocasia Portora, Alocasia wentii...
Colocasia and Xanthosoma are new-World elephant ears. Many are hardy in zones 7b and warmer. Mulch well in fall for best results. They can grow in full sun if kept moist to soaking wet in the hotter months. Try them as pond marginals in diret sun for crazy fast growth. Feed them heavily in the summer too.
Cultivated Colocasias are mostly variants and cultivars from one species, Colocasia esculenta. A couple other species exist, but are less commonly seen (Colocasia fallax…). Colocasias are all grown the same way- bright and sunny. They can stand full sun very well as long as they are properly hydrated. They even make great additions to bog gardens or pond shallows. Colocasias can grow at a surprising rate if their needs for light, moisture, and nutrition are met. Colocasias come in all shades of green and purple up to nearly black. They can be rather monochromatic, mottled, or variegated to differing extents. Expect best color when grown in full sun- even the “black” varieties will be green in low light. Colocasias appreciate wet feet, especially in the heat of summer. If you cannot provide enough moisture, some shade in the middle of the day is wise. Feed Colocasias well during the growing season with a soluble, balanced fertilizer at full strength; or incorporate extended release fertilizer in their substrate. Cut back on fertilizer in accordance with the weather, withholding it completely in the winter if growth stops. Moisture can also be gauged by the time of year, temperature, and growth rate. In colder climates, colocasias will die back to the ground after a frost or two. Colocasias sometimes grow in heavy mud naturally, but this is not a wise choice for “captive” plants since mud will quickly stagnate and prevent adequate aeration at the roots. On muddy stream banks, the roots get a good supply of oxygen from the moving water. Plants can be overwintered in the ground up to zone seven if well mulched (three inches or so); or tubers can be dug up, stored nearly dry and cool and replanted in spring after the last threat of frost. Plants grown in containers can be overwintered indoors in a bright location that does not go below freezing. A basic potting mix of one part sphagnum peat moss to one part perlite will work great.
Xanthosoma are grown identical to Colocasias- bright, wet, and well fed. Xanthosoma sagitifolium occurs in wet roadside ditches throughout the southern United States. It is usually medium green and looks nearly identical to the green form of Colocasia esculenta. However, Colocasia have a rounder leaf compared to a slightly arrowhead shaped leaf in Xanthosoma, and Colocasia commonly have a purple or pink dot on the upper leaf surface opposite where the petiole meets the leaf.
When grown outdoors, elephant ears are virtually pest free. Watch for slugs and snails that thrive on moist soil conditions elephant ears enjoy and appreciate munching on tender new leaves as they emerge. Iron phosphate pellets (Sluggo) are very effective and fairly safe to use around the yard compared to the traditional Metaldehyde baits. The most troublesome pest for all elephant ears in the home is mites. Low humidity allows them to persist to chew on the soft, broad foliage. Frequent mists with an insecticidal soap solution will help keep mite populations from exploding. Alcohol can be effective on mites, but will damage the leaves of some elephant ears. If overwintering plants inside, take them outside on decent days and hose the entire plant off. Both sides of the leaves, stems, etc. then apply a generous coat of your favorite smothering insecticide (soap, oil, etc). Mite bites will eventually make a leaf unsightly, but the good thing is that ee’s grow at a fast rate and will replace damaged leaves in a short time. If an ee becomes infested with pests, it is often best to simply cut the leaves back and allow it to start from scratch.
Elephant ears can also be grown in containers either in the yard, or in the greenhouse or home. Use your favorite potting mix as long as it is well drained. Colocasias and Xanthosoma can even be grown sitting in a shallow tray of water. Choose varieties wisely; some of the larger growing elephant ears are not good windowsill candidates! Although plant size is sometimes tempered by potting roots tightly. Most elephant ears will need a pot at least four inches (for the jewel and African mask Alocasias) to twelve inches or more (for the larger Alocasias, Colocasias, and Xanthosoma) as a mature plant.
Elephant ears are very amenable to semi-hydroponic culture. Check out our article in the spring 2011 issue of Orchid Digest and see our semi-hydroponics page.
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