Colocasia antiquorum is a highly variable tropical plant. It is synonymous with C. esculenta, which was previously considered a separate species. Believed to have been cultivated very early in anthropogenic history, this well-known herb goes by many names around the world. Generally, it is referred to as taro, elephant ear, dasheen, or kalo, and may sometimes be confused with yam and sweet potato.
The cultivar known as ‘Imperial Taro’ is formally listed as C. esculenta var. antiquorum ‘Ilustris’. It is a member of the large Araceae or arum family that is known for producing specialized inflorescences associated with a leaf bract. The aroids of this family are mostly tropical, though many are able to survive in mild temperate zones with proper care. Taro is native to Southeast Asia and Southern India, but is now naturalized in many other parts of the world. The ‘Ilustris’ cultivar, on the other hand, has its origins in Polynesia.
This plant not only has edible uses but ornamental too, as its dramatic foliage sets it apart. Its large, heart-shaped leaves can extend to a length of 3 feet (91 cm). The margins and veins are bright green, like the undersides of each leaf. In contrast, the spaces between these veins are a deep shade of purple to black. These velvety leaves arise from underground rhizomes and are borne on erect petioles that rise as far as 3 – 5 feet (91 – 152 cm) above the ground. The attractive leaves make up for the rare, largely inconspicuous blooms.
Imperial taro is a great candidate for pond-edge or bog garden cultivation as it requires regularly moist or wet soil. This perennial can even withstand occasional flooding in wetlands. While its rhizomatous root system can persist through the years, the leaves tend to turn yellow once its corms are ready for harvest. The corms, which are white to light purple in color due to phenolic compounds, are rich in starch.
Imperial Taro Growth, Hardiness & Climate
This cultivar rarely occurs outside of cultivation areas and gardens, though it may become established in rich soils along river banks and streams. It thrives best in high humidity conditions with frequent rains to keep the soil wet. In some areas, cultivation plains are regularly flooded to ensure that the root systems are exposed to oxygenated water. Stagnant water can, unfortunately, harm the plant as low oxygen conditions may encourage basal rotting.
Optimal temperatures for imperial taro cultivation range between 21 – 28˚C (70 – 82˚F). This species can tolerate temperatures outside of this range (up to a low of 10˚C or 50˚F) as long as all other parameters are kept at an optimum. In terms of soil, a slightly acidic mixture with high amounts of organic matter is preferred. Filtered or partial sunlight is best for the herbaceous foliage of this species. Due to these preferences, this plant is hardy to USDA zones 9 – 11. It should ideally form dense clumps in these zones when protected from excess heat and when provided with flowing water.
How to Plant Imperial Taro
Colocasia antiquorum ‘Ilustris’ can easily be planted with the use of its bulbs or corms. You can make use of bulbs that have gone dormant as these should begin to produce new roots and shoot tissues as temperatures warm. Make sure to remove any decaying or dead leaf layers around the bulbs to prevent bacterial or fungal accumulation. While doing so, try to locate the growth tip.
Place pre-moistened soil into any type of pot with a circumference that can comfortably accommodate the entire bulbs and any offsets. The bulbs should be placed around 2 inches (5 cm) deep in the soil, with the growth points facing upward. If unable to locate the growth points, you may place the bulbs on their sides. Fill in the rest of the pot with soil, making sure to cover the bulbs completely. You can choose to leave up to an inch (2.5 cm) of free space along the top of the pot to prevent water from overflowing.
Do be patient while the bulb exits its dormant stage. Avoid fully soaking the soil until new tissues begin to appear on the soil’s surface. If you overwater the bulbs before they have exited dormancy, they may rot. Place your pot in an area with filtered sunlight to encourage the new tissues to grow in the right direction. Once the plant has fully established itself in the soil, you may outplant it into its permanent position.
How to Care for Imperial Taro
Imperial taro is known for being extremely easy to grow and care for. Simply remember to keep the soil moist or wet. You may regularly provide the plant with a well-balanced N-P-K fertilizer (10-10-10 or 20-20-20) as its soil should be kept fertile. A concentration that is around half the values indicated on the label should suffice. Fertilizer application can also hasten the growth of its corms, which should reach harvest size in just 7 – 10 months.
To prevent physiological damage to the leaves, ensure that they are not exposed to scorching sunlight or intense heat. Scan the foliage for any damage or pests every now & then and remove any parts that have been compromised. Keep in mind that the corms will swell and potentially outgrow small pots. You may need to repot root-bound plants that have caused their pots to buckle or stretch out.
How to Winter Imperial Taro
The foliage of imperial taro will naturally become yellow and die back in winter if the plant is located in cold climates. In temperate zones with warm summers, the leaves can stay green all year round. Avoid cutting back leaves unless they have started to become yellow, as their chlorophyll is necessary for generating some of the root system’s energy requirements to survive through winter.
If winter temperatures in your area dip to below 10˚C and tend to bring in frosts, you will have to treat your taro as an annual. If possible, you may also opt to bring your entire plant indoors for the duration of winter. Only consider this method if you are able to regulate indoor temperatures and provide your plant with light and humidity. You may also choose to dig out the bulbs and encourage them to grow dormant before the next planting season.
Before digging them out, cut back the foliage until about 2 inches (5 cm) is left above the bulb. Let the bulbs rest exposed (in a shaded area) for a day prior to placing them in a storage box. You can fill the box with peat moss, wood shavings, or paper fillers to prevent excess moisture from causing rot. Place it in an area where the temperature can be maintained at 55 – 60˚F to prevent plant growth and decay.
Is Imperial Taro Invasive or Toxic?
Colocasia species have the tendency to be invasive due to their rhizomatous root systems. C. esculenta or antiquorum is considered a weed plant in some parts of the Caribbean and North America. The ‘Ilustris’ cultivar, however, is less prone to being an aggressive weed in comparison to other elephant ear varieties. If your area has fertile soil and generally has humid conditions, you may still wish to grow this cultivar in pots to prevent it from competing with other plants.
Due to this species’ calcium oxalate content, it can be considered mildly toxic. Consumption of the plant in its raw form can irritate the digestive tract and cause unpleasant sensations around the mouth and tongue. Ingestion of large amounts of this plant can also be harmful to pets.
Is Imperial Taro Edible? Will Fish Eat it?
Imperial taro roots and leaves are edible, but they must be steeped in water, thoroughly dried, or boiled to neutralize the calcium oxalate crystals. The corms of the plant are a fantastic source of starch and can be dried and ground to produce flour. The leaves can be used to wrap baked food. Even the leaf petioles are edible and are likened to celery stalks. Consumption of this plant is also associated with medicinal uses as it contains antibacterial compounds.
Ensiled leaves of C. esculenta have experimentally been used as a replacement for fish meal for livestock feeds. Fish themselves are unlikely to consume the roots or leaves of this plant due to its crystal content.
Where to Buy Imperial Taro & Seeds? (UK & US)
Imperial taro can be purchased from garden centers and ornamental plant stores in many tropical areas. If located in a temperate zone, you may have more luck acquiring this species through online plant portals. As the weed potential of taro has been highlighted, do make sure that cultivation of C. esculenta or antiquorum is permitted in your area prior to making a purchase.
