Colocasias are tropical looking perennial plants known within the western world as alocasia or taro. Ornamental Colocasia (the focus of this article) are important garden plants because they add a bold, tropical look, and within the southern US they create fabulous garden specimens. The last 20 years has seen an enormous increase within the colors, shapes, and sizes of garden-worthy alocasia s because of the tireless work of breeders like Hawaii’s Dr. John Cho and plant explorers like Allan Galloway. There are now alocasia s in exciting, landscape-worthy colors like black and white and giant alocasia plants with leaves (in extreme cases) larger than a person’s .
Colocasia (Leucocasia) gigantea ‘Laosy Giant’
How to Grow Elephant Ears
Colocasia culture is fairly simple. Just remember the mantra: “more water + more nutrients = more elephant ear“. this is often very true for the enormous alocasia plants like Thailand Giant and Laosy Giant whose leaf size depends greatly on available resources. Gardeners can grow potted taro cultivars in shallow bodies of water, but other species, like Colocasia gigantea, need better drainage. Colocasia grows alright as a pond marginal, and when grown in containers, the pots are often submerged slightly during the summer months. Containers of Colocasia must be brought indoors in cold winter climates.
Colocasia (Leucocasia) gigantea ‘Thailand Giant’
Colocasia are heavy feeders and for best performance require organic fertilizers and rich organic soil with many composted material. A pH from 5.5 to 7.0 is satisfactory. Most Colocasia prefer bright sunlight, unless grown in extremely hot, low humidity climates, where some light shade are going to be necessary. Elephant ears should be planted slightly deeper than they grow within the pot, or when planting dormant corms, put them at a depth of 2″ to 4″.
During the season , Colocasia will continually produce new leaves because the older leaves continually die out . Growers will want to periodically remove the dead leaves so as to stop the leaves from covering ground-cover plants and to stay the garden looking tidy. Some gardeners could also be sensitive to the juices of cut Colocasia stems (which contain calcium oxalate) and should notice some skin or eye irritation unless they wear gloves or wash their hands soon after contact.
How to Propagate Elephant Ears
Colocasia is often propagated by seed collected about 30 days after fertilization, and surface sowed as soon as possible after drying. Germination should happen within 21 days. additionally, you’ll divide the larger corms, collect offsets (cormels) or separate the new plantlets that form at the rhizome recommendations on the running types. The long runners form nodes along their length, and new growth buds exist at each of those nodes.
How to Overwinter alocasia bulbs
As the day length shortens, Colocasia switches their energy resources from producing leaves to flower and bulb production. the assembly of leaves will become slower and therefore the alocasia bulb will swell noticeably. At this point, most of the present season’s roots will die out. it’s important to know this physiological change so as to successfully overwinter your alocasia bulb. we’ve recently learned that Colocasia tubers migrate upward within the soil over time then every few years, we obtain and re-plant the bulbs to stay them at a perfect depth of 4″.
There is also quite difference in winter hardiness of Colocasia. Colocasia gigantea Thailand Giant Strain may be a solid USDA Hardiness Zone 8b, while Colocasia ‘Pink China’ is reportedly winter hardy to Zone 6. the remainder fall somewhere in between. Typically, triploid cultivars are a few half zone hardier than their diploid counterparts. From Zone 8b south, most Colocasia should be reliably winter hardy within the ground without protection. This successful zone of cultivation also extends into Zone 8a, but some marginally hardy cultivars could also be slow to return after a tough winter.
In Zone 7b, most Colocasia will return without the advantage of mulch with a couple of exceptions. Colocasia affinis ‘Jenningsii’, taro ‘Nancy’s Revenge’, Colocasia gigantea Thailand Giant Strain, and taro ‘Elepaio’, need slightly warmer winters (zones 8a-8b) to return without the advantage of winter protection. during this hardiness zone, hardy Colocasia may survive, but the most alocasia bulb can freeze and decay during the winter, leaving only the smaller offsets to survive. during this case, returning plants might not reach full size during the following season. to beat this, cover the clump after the primary frost with a 1′ tall pile of shredded leaves, which works well to guard the most corm. The plants will grow through the leaves once they re-emerge in spring.
Colocasia esculenta ‘Bikini Tini’In colder zones, an equivalent principle are often used but with a rather altered technique. Assuming the plant has made good growth during the summer, after the primary frost, encircle the bottom of the plant with a 3′ diameter cage of hog wire and fill it with shredded leaves. If left unshredded, the leaves will compress and hold unwanted moisture against the plant, causing it to rot. When new leaves emerge in spring, remove the cage and filler.
Northern gardeners (Zone 7a and north) will got to bring their elephant ears indoors before the temperatures drop below freezing. Over winter, elephant ears are often grown indoors as potted house plants. If you grow your elephant ears outdoors in containers during the summer, crop about the highest two leaves, then bring the pot indoors the before first frost. If growing elephant ears within the ground during the summer, pot them before frost during a n appropriately-sized container and place the pot in a cool area (45-60F is ideal) where the plant receives bright light. don’t over water in winter because the plants are still semi-dormant.
Most of the dwarf non-corm forming species should be kept growing during the winter, along side non-tuber forming selections of taro including taro ‘Black Magic’ and taro ‘Nancy’s Revenge’. Colocasia gigantea Thailand Giant Strain is additionally slow to develop an outsized corm, so is best kept in active growth.
Varieties of Colocasia that form large corms, like most taro cultivars, are often dug up and therefore the corms stored in sphagnum for the winter. they have to be kept during a dry, cool, but above-freezing location. don’t store in an airtight container which can allow moisture to create , causing the tuber to rot. Don’t forget to label your tubers!
Clumping versus Running Elephant Ears
Colocasia is often divided into two groups: the clumpers and therefore the runners, although some cultivars blur the lines. the normal sort of edible Colocasia grown for taro is taro variety aquatilis. this type produces very long stolons (above ground runners), forming an outsized mass of plants for a short time. While this trait could also be good for giant plantings, it’s less desirable during a garden of limited space. In tropical climates like the Gulf Coast, they will truly take over, which provides all elephant ears an undeservedly bad reputation in these climates.
Many modern elephant ears bred with these early plants still have above ground runners, although the degree of running is somewhat less. the sole Colocasia that spread by below ground runners are taro ‘Illustris’ and its close cousins, taro var. antiquorum ‘Black Beauty’ and taro ‘Coal Miner’.
Colocasia esculenta ‘Coal Miner’
The clumping varieties have a beautiful vase shape within the garden, and lots of of the cultivars available today are very slow or are nonexistent runners, a bit like me.
The History of Colocasia
Colocasia esculenta ‘Jack’s Giant’ The common name, elephant ear, is occasionally wont to describe plants in related genera like alocasia (upright elephant ears), remusatia, and xanthosoma. The leaves of the alocasia plant and its relatives are typically large, flat and sagittate to broadly ovate in shape and really do appear as if they belong on a pachyderm’s pate. The term, elephant ear, is additionally wont to describe both the unrelated plant Burdock within the Arctium also as a delicious fried dough treat at the most State Fairs. curiously enough , the genus name Colocasia is additionally used for a eu moth. There are dozens of common names for alocasia utilized in other parts of the planet including kalo, culcas (from which the genus name Colocasia is derived), eddo, imo, dasheen, cocoyam and malombo.
The alocasia bulb may be a vital staple food crop and fodder crop within the tropics, such a lot in order that alocasia bulbs (mainly Colocasia esculenta) are the 14th most generally consumed vegetable on earth. alocasia plants are in cultivation for over 28,000 years as a food crop in equatorial regions including India, China, Southeast Asia , Indonesia, Polynesia, the Mediterranean, Africa, and South America. Because Colocasia has been in cultivation for therefore long, nobody knows needless to say where it truly is native, but all evidence points to somewhere in Southeast Asia . All parts of the plant are edible if they’re thoroughly steamed or boiled to first remove calcium oxalate crystals. The cooked leaves are utilized in Hawaiian luaus and therefore the corms are mashed into poi. before the mid-1800s, Colocasia were a staple food crop and therefore the native Hawaiians cultivated many varieties. Modern agricultural crops have supplanted Colocasia in Hawaii and therefore the number of commercially grown varieties has plummeted. However, beginning within the 20th century, agricultural scientists began to preserve the Hawaiian Colocasia varieties and breed new ones. These breeding efforts have also led to the event of the many new ornamental varieties.
Colocasia belong to the araceae family (whose members we call aroids) and share the unique spathe and spadix inflorescence of other aroid genera like Arisaema (Jack-in-the-Pulpit). The Colocasia contains slightly quite a dozen species with several new ones being described recently. The overwhelming majority of the cultivars utilized in ornamental gardens belong to taro . There also are alittle number of attractive sorts of lesser known species like Colocasia affinis, Colocasia fallax, Colocasia gigantea, and Colocasia heterochroma available for discriminating gardeners. Other species can also have garden potential but aren’t yet in cultivation. These include Colocasia bicolor, Colocasia formosana, Colocasia gaoligongensis, Colocasia gongii, Colocasia konishii, Colocasia lihengiae, Colocasia menglaensis, Colocasia oresbia, Colocasia tibetensis, and Colocasia yunnanensis. Elephant Ears have a worldwide distribution and grow natively in most tropical and sub-tropical countries.
alocasia Breeding
We first took an interest in elephant ears within the late 1980s, but it had been on a 2003 trip to Hawaii trying to find elephant ears that the scope of our interest and knowledge of the genus changed dramatically. Here, I met Dr. John Cho, of the University of Hawaii Experiment Station on Maui. A plant pathology professor, Dr. Cho was breeding edible Colocasia for leaf spot resistance, unaware that anyone would have an interest in their ornamental value. I used to be speechless at his complete collection of all the known cultivars of Hawaiian edible taro, alongside his amazing hybrids. within the ensuing months, we established a proper trialing relationship with Dr. Cho and therefore the university, which continues to the present day. per annum thereafter, Dr. Cho has visited Plant Delights, where we spend several days evaluating his hybrid elephant ears and discussing possible future crosses. In Fall 2005, the management of the program was handed off to Planthaven, a California-based plant marketing firm and therefore the first six plants were commercially released in 2008. Dr. Cho retired in 2009 but is constant his breeding work to develop unique and garden-worthy ornamental taro selections.
Elephant Ear Colors
The leaves of elephant ears are their most vital ornamental trait. the foremost common color may be rich emerald green, but now leaf colors can range from black or brown to chartreuse gold.
Colocasia esculenta ‘Nancy’s Revenge’
In addition, the leaves will vary in glossiness from a matte finish (common) to a high gloss shine (rare in colocasia). it’s also quite common to seek out leaves containing thick mid veins and major side veins of a contrasting color. the main veins could also be green, purple, creamy ivory, yellow or pink (who doesn’t sort of a pink elephant?). The extent of the vein color varies. The coloration may only occur at the “piko” (the “belly button” on the highest of the leaf opposite the purpose of attachment to the petiole) or may run through all of the main veins of the leaf. additionally , the mid-vein coloration often leaks into the encompassing lamina tissue and should form an oval shape like taro ‘Nancy’s Revenge’ because the season progresses. This trait appears to be triggered at an equivalent time as flowering and should be under an equivalent genetic control. it’s not uncommon for rock bottom of the leaf to possess a special lamina or vein coloration than the highest of the leaf, which provides a pleasant flash of color on windy days. The newly appearing leaves may have a special color than when the leaves are mature.
Breeders also are selecting variegated cultivars. Variegation in Colocasia often takes the shape of variable sized splotches or flecks of color on the leaf surface. Variegations in Colocasia are somewhat unstable and reversions are common. Also, the variegation may appear in sectors or only on one side of the leaf. Common color combinations in variegated elephant ears are light green to yellow splotches on dark green leaves, green splotches on purple leaves, or purple splotches on light green or dark green leaves. The leaf variegation also runs down the petioles, where it’s often more visible than within the leaves.
The elephant ears that gardeners seem to urge most excited about are the solid purple-leaved or solid black-leaved esculenta cultivars. the colour purple makes an excellent contrasting color the garden and on plants as large as elephant ears, purple makes a bold statement.
Colocasia esculenta ‘Black Coral’ PP 23,896
The purple coloration can vary from a dusty gray-purple to extremely dark purples which appear black. Black alocasia plants are wonderful to possess unless you wish to spend time in your garden at night! The purple-leaved cultivars usually have a matte finish, although there’s one moderately glossy purple-leaved cultivar within the trade, taro ‘Diamond Head’ PP 19,939 . within the future, search for purple- or black-leaved cultivars with extremely glossy foliage (e.g., Colocasia ‘Black Coral’).
In addition to paint , breeders are selecting for various leaf shapes and textures. Leaves could also be somewhat arrow-head shaped (sagittate), or could also be roundish on the edges , sort of a fat arrow-head. Generally, the leaf tip (apex) is pointed (acuminate) and therefore the leaf base has two pointed or rounded lobes of varying size with a “Y” shaped sinus between them. The leaf margin could also be smooth or ruffled. The leaf surface could also be smooth, somewhat puckered, or maybe cupped in such how that it can hold quite little bit of water. Some cultivars that are within the pipeline immediately will feature the fresh trait of reflexed leaf edges. All Colocasia leaves are hairless (glabrous) and have a smooth waxy feel.
The leaves are delayed by very long thick petioles that emerge directly from the underground corm. The petiole to leaf attachment is “peltate”. In other words, the petiole doesn’t attach to the sting of the leaf, but rather to the center of the lower surface of the leaf. As a result, the leaves are held perpendicular to the petiole. The petioles grow nearly straight up, but the leaves are generally upward or outward facing. The petioles may have attractive colors that contrast with the leaf. The petiole color could also be black, purple, burgundy, maroon, red, pink, cream, or they’ll be streaked with several colors directly . The petioles are thick enough in order that their color is definitely noticed and may be a nice ornamental feature.
Elephant Ear Flowers
Garden Colocasias isn’t known for his or her flowers (inflorescences, actually) because they’re hidden underneath the leaf canopy. However, the inflorescences are large, quite attractive, and regularly fragrant…although barely because the spathe opens. The spathe and spadix inflorescence (think calla aka zantedeschia, a fellow aroid) is persisted a brief peduncle and should be up to 8″ long by 3″ wide (but usually smaller). Spathe color is typically white or yellow and spadix color can vary from creamy white to yellow or orange. The fruits (which are rare unless you hand-pollinate) are a cluster of small berries, 3 to 5mm wide, that is greenish or yellowish in color with several seeds inside.
Elephant Ear Size Matters
Colocasia varies in size from the diminutive Colocasia heterochromia ‘Dark Shadows’ at only 8″ tall to the mammoth giant alocasia plants like Colocasia gigantea Thailand Giant Strain and Laosy Giant which may top out at over 9′ tall in ideal conditions. Most varieties fall within the 3′ to 5′ tall range. The leaves also vary in size from only 4″ wide by 6″ long on Colocasia heterochromatin ‘Dark Shadows’ to 4′ wide by 5′ long in Colocasia gigantea Thailand Giant Strain. The large-leaved giant alocasia plants are truly a tremendous sight to behold.
For the needs of this text , we’ll divide Colocasia into 3 categories: the “dwarf” types, the “giant” types, and therefore the “esculenta” types, as these are the categories that have different uses within the garden. within the following paragraphs, we’ve separated the cultivars into these categories so as to assist you decide on the simplest plants for your site.
Dwarf Elephant Ears
The dwarf Colocasia includes any taxa that are but 2′ tall. These are small plants that look good planted en bloc or as accessories for other small tropical plants. There are some small taro cultivars, but they’re going to be discussed under the “esculenta” type Colocasia.
Colocasia affinis ‘Jenningsii’
Colocasia affinis may be a charming but little-known dwarf alocasia that’s loved for its picture-perfect, velvety charcoal leaf face with central charcoal veining and an enormous silver blotch within the center of every leaf. Much of the fabric sold as this is often actually taro ‘Illustris’ (no central silver pattern and green veins). This 1′ tall, light shade and moisture-loving species has proven to be an outstanding plant . Throughout the summer, the dense clumps are adorned with small flowers of the yellow spathes and spadix persuasion. For us, Colocasia affinis resprouts in late June, so don’t panic! Colocasia affinis is represented within the trade by the cultivar Colocasia affinis ‘Jenningsii’. Since we’ve not grown other cultivars of this species, we don’t skills different this is often from the standard species. Like Colocasia heterochroma, Colocasia affinis goes winter dormant no matter the temperature. (Hardiness Zone 8-10)
Colocasia fallax may be a delightful dwarf alocasia from China. Unlike most other elephant ears, this light shade and moisture lover forms rounded leaves of velvety medium green, each highlighted by a good silver streak down the middle vein, with smaller silver veins radiating from the middle to the leaf edge. The plants are adorned all summer with small yellow spathe and spadix flowers. The 15″ tall plants make a 4′ wide patch in 2 years (in very wet soils) by means of short, above-ground stolons…quite unique and quite beautiful (Hardiness Zone 7b-10).
Colocasia fallax ‘Silver Dollar’
Colocasia fallax is represented within the trade by the cultivar Colocasia fallax ‘Silver Dollar’, a PDN introduction composed of small, rich green leaves far more rounded than normal and also highlighted by narrow silver veins and a good central silver blotch…not to say held atop cinnamon-colored petioles. We also are growing another selection, Colocasia fallax ‘Silver Splash’, which seems a touch taller, reaching 18-20″, but spreads less vigorously than other forms we grow.
The smallest of the dwarf Colocasia is Colocasia heterochroma which measures a Lilliputian 8″ tall. This fascinating new Colocasia species was discovered at 4,000′ elevation in Yingjiang, Yunnan , China. The plant was subsequently named in 1993 by China’s aroid expert, Dr. Li Heng. Colocasia heterochroma, a June emerger which prefers light shade, forms alittle patch via short underground rhizomes to only 8″ tall x 18″ wide…a far cry from its taller cousins. The 6″ long x 4″ wide leaves are silvery green with a dramatic black interveinal leaf pattern. Unlike most other Colocasia species, it goes dormant in winter albeit kept warm. Colocasia heterochroma ‘Dark Shadows’ may be a cultivar that we named with particularly dark leaf patterns. (Hardiness Zone 7b-9)
Mid-Sized Elephant Ears
The second sort of Colocasia during this article is the taro cultivars which represent the bulk of the taxa within the trade today. They vary tall from 2.5′ to 5′ tall, and where the climate allows, prefer full sun unless indicated differently. taro has the widest color and leaf form variation, and range of variegation of elephant ears. Some have a clumping habit, and a few are runners. The solid green-leaved, clumping taro is that the commonest within the trade and may often be found as a dormant corm even within the large box stores. The common taro produces a 5′ tall, green-leaved plant with 2.5′ wide by 3.5′ long leaves with green petioles and a smooth margin (leaf edge). taro is represented within the trade by the subsequent cultivars.
Colocasia esculenta var. antiquorum ‘Black Beauty’ may be a superb 2006 Agri-Starts introduction, a shocking mutation of the favored Colocasia ‘Illustris’. If you’ll imagine intensifying the black leaf color and removing a number of the green veins of taro var. antiquorum ‘Illustris’, you’ll visualize taro var. antiquorum ‘Black Beauty. within the ground, taro var. antiquorum ‘Black Beauty’ forms a 30″ tall patch, spreading underground like taro var. antiquorum ‘Illustris’, making a 4′ wide patch in 3-4 years…simply stunning. (Hardiness Zone 7-10)