How to Plant, Grow and Care For Colocasia

Colocasia is among the large-leafed plants that commonly go by the name Elephant Ear. They join Alocasia in using this nickname. Although the plants are similar, there are some minor differences. Taro is another moniker that one species of Colocasia claims, referring to its edible corms or roots. 

You may have seen Taro chips in the supermarket, as these pretty white and light purple roots make a lovely, crunchy chip that is as pretty as it is tasty. It can also be baked like a potato. It has a slightly sweet flavor, and the texture is denser than a regular potato.

Colocasia plants are native to Africa, Southeastern Asia, and India. In addition to their decorative value, they have been widely grown as a food source in their native environments. Various species have also been used historically for health remedies.

Classification

Colocasia is an herbaceous perennial. It can be grown as an evergreen in warmer climates, but if the temperature drops below freezing, the foliage will suffer damage, and the plant will ultimately die back to the ground.

Don’t worry; the roots are winter hardy in zones 8 and warmer. It is a member of the Araceae family and is related to other plants like Caladium and Alocasia.

C. esculenta (Taro)

Taro is the most commonly found ornamental Colocasia. It is harvested as a food crop in its native eastern Asia and has been widely hybridized to create cultivars in many different sizes and colors. 

Some varieties have almost black leaves, and others are multicolored, in addition to completely green varieties. Most nurseries carry this species. They are easy to care for and disease resistant. 

C. gigantea ‘Thailand Giant’

This species, also known as ‘Thailand Giant’ Colocasia, can grow up to 10’ tall and wide, making it a great choice for a privacy hedge if you can obtain them.

Gigantea produces pretty, yellow flowers in summer that have a nice fragrance. It is frost-tender, but the heart-shaped, blue-green leaves reappear in spring. This is a fast-growing species.

C. affinis ‘Jenningsii’

This dwarf Colocasia only reaches about 18” tall and wide. It makes a great border and has lovely leaf coloration. The leaves are deep green to black and are veined with a silvery color, with a concentration of the color in the center of the leaves. 

Leaf Formation

The leaves of Colocasia give it its nickname Elephant Ears. The large, shield-shaped leaves resemble the ear of an elephant. These leaves can grow exceptionally large in some varieties, with some leaves reaching up to 60” long, and come in various shades of green and purple.

The main difference between Colocasia and its cousin Alocasia is the direction of the leaves. Where Alocasia’s leaves typically point upward, Colocasia has leaves that hang downward, pointing toward the ground. They are heavily veined, with the veins emanating outward from the upper center of the leaf, where it connects to the stem.

Flowers

All Colocasia plants are flowering, although the flowers tend to take a backseat to the leaves in ornamental value. Some gardeners even remove the flowers, as they can take energy away from forming larger, denser foliage. 

The flowers appear in shades of white, yellow, and green and have a similar appearance to those of a peace lily. They are aroid-type flowers, with a single large petal or spathe surrounding a large, central spadix. Most species of Colocasia are pollinated in their native habitat by drosophilid flies.

Planting

If you are planting bulbs, bury them about 4” deep and 2 feet apart for smaller varieties and 8” deep and 3’-4’ apart for larger varieties. Young plants should be planted with the root ball at the level of the surrounding soil. Dig a hole as deep and twice as wide as the container.

You can also purchase pre-rooted Colocasia plants from a nursery. Transplant these into a hole 1.5-2 times larger than the root ball. Backfill so the soil remains even at its original level.

Propagation

Colocasia is very easy to propagate, and if you desire to expand the space where they are planted, it can be done quite quickly. Propagation can be done in 3 ways:

1. Division of the main corm
2. Separating offsets
3. Cutting the tubers

Corm Division

This method takes the most time and has a lower success rate than others, so it is typically the least popular. Dividing the main corm involves digging up the main corm and dividing it into pieces.

You can use a sharp, sanitized knife to split the corms. Each piece should have a developing eye.

Plant these portions of the corm in propagation trays, maintain continuous moisture, and wait for each eye to become a new plant. 

Separating Offsets

Colocasia plants produce offsets fairly freely. If they remain attached, these offsets will typically not grow as large as the mature portion of the plant. Once detached and allowed to grow independently, they should grow as large as the parent plant.

If your plant is mature, healthy, and visibly producing suckers, lift it from the soil. Use your hands or sharp pruners to remove the offset tuber suckers and replant them in a container just like their mother plant.

Cutting Tubers

If you want to harvest the roots of your Colocasia (Taro), this is the most effective propagation method. When you dig up your corms at the end of the season, cut a portion of the corm attached to the above-ground growth.

Re-pot these portions of corm in pots and allow them to grow over the winter. In the spring, they will return as if the corm had not been severed.

How to Grow

Colocasia is a wetland plant that prefers mild climates and lots of humidity. It has been naturalized all over Florida, where it can become invasive when not managed properly. In a container or a temperate climate, this shouldn’t be a problem.

Light

While some varieties of Colocasia can survive in full sun, the ideal light conditions for these plants are dappled light or bright, indirect light. As a rule, the darker the leaves, the more sun the plant will need. Colocasia varieties with very dark purple leaves will fare better in full sun than those with brighter green leaves.

The afternoon sun tends to be hotter and more intense than the morning sun. If you live in a hotter climate, give your Colocasia some shelter in the afternoon. You will notice the plant becoming droopy and wilted if it gets too much direct sun.

Water

Colocasia plants need a lot of water. These wetland plants need to have consistently moist soil. Without enough water, it will wilt, and the leaves may turn brown. Root rot is not usually a problem. They can tolerate and truly crave ample watering.

Once established, it will be a bit more drought-tolerant, as the leaves act as a shield over the soil around them. The shade provided by their very large leaves helps the soil to retain moisture.

Soil

The best soil type is loose, nutrient-dense, and able to hold moisture. Good drainage is never bad, but these plants can thrive in a swamp, so the main concern is moisture and nutrients.

A mixture of clay or loam with compost and a slightly high acidity level will be the most appropriate soil for your Colocasia. Adding worm castings to your soil is a great option, as they can hold up to ten times their weight in water.

Fertilizer

Colocasia is a heavy feeder. It needs lots of nutrients in the soil, so it is best to enrich the soil before planting to give your plant the best start. You can fertilize this plant regularly without the risk of overdoing it.

A standard 20-20-20 fertilizer can be administered as often as weekly. However, every other week is less likely to drain through the soil quickly, reducing the risk of accidental fertilizer pollution in groundwater. 

Climate and Temperature

Colocasia like warm weather and lots of humidity. You will see the most growth from your plant when the temperatures range from 68°-86°F, but they are relatively tolerant of temperatures over 50°F. When the temperature drops below 40°F, expect little growth from your plant. A frost will do significant damage to foliage. 

Most types of Colocasia are cold hardy to zone 8, and some will even overwinter in zone 7 if provided a healthy layer of mulch to protect the roots. I live in zone 8, and while my Colocasia plants die back in the winter, they come back stronger and bigger every year. 

As a houseplant, Colocasia is happy with indoor temperatures but is likely to need some supplementary humidity. A humidity level of 50% or higher will be optimal for these plants indoors and out. If you live north of zone 8, you can always dig up your tubers, bring them inside, and replant them in the spring. 

Pruning

This plant benefits from regular pruning for health and aesthetic appeal. Damaged leaves can lend an unhealthy appearance to your plant and invite fungal or bacterial diseases. It is best to trim off any damaged foliage, cutting these stems down to about 2” from the base of the plant.

As the leaves age, they will naturally droop. To maintain the plant’s appearance, trim them off using a clean, sharp blade or a pair of sharp, sterile pruning shears.

In winter, after the first frost has killed off the foliage, trim off all the leaves down to about 6” from the base of the plant. If allowed to thaw, these leaves will become soft and be at risk of rotting and causing harm to the root system. In preparation for spring, you can remove the last bits of dead or dried-out foliage.

Maintenance

Colocasia will multiply yearly, which can become a nuisance if you want to keep them contained. If possible, new plants should be removed from the main root to prevent them from regrowing during the season.

If you prefer to allow them to spread, they require very little additional maintenance. Keeping damaged foliage trimmed will help your plant look its best.

Pests and Diseases

Once established, Colocasia is very easy to maintain. They do appeal to some common garden pests, but because of the sheer magnitude of the plants, once they mature, there is typically very little damage done. 

Prevention is the best way to deal with pests and diseases, but sometimes they happen anyway. It’s good to be aware of the different issues your plant may be suffering from so that you know what to look for when you purchase the plant. Most pests and diseases arrive on new plants.

If you are keeping Colocasia as a houseplant, the most important thing to do when you suspect a disease or infestation is to isolate it from other plants. This can help to stop the spread and spare your other houseplants.

Armyworm

Armyworms are the larval form of the Spodoptera genus of moths. They resemble other caterpillars and love to munch on Colocasia’s tender leaves.

If the infestation is small, it’s best to remove these insects by hand and avoid using chemicals. BT, or Bacillus thuringiensis, is a soil bacteria that is also effective in treating armyworms.

Eight Spotted Flea Beetles

These tiny beetles are only about ⅛ inch long or shorter. They are black with 8 white spots on the top of their wings, making them resemble a garden hero, the ladybug. These beetles eat plants, though, and they can cause a lot of unsightly damage. The adult beetles create pits and rounded holes in the plant’s foliage.

The natural control for flea beetles is wasps. However, the specific wasp that eats the flea beetles is only found in the eastern half of the United States. In the absence of natural predators, insecticidal soaps can eradicate these pests. A spinosad spray is even more effective; spinosad is another form of soil bacteria that works as a natural pesticide.

Aphid

Perhaps the most notorious group of garden pests are the aphids. These tiny sap-sucking insects use their mouthparts to pierce through the leaves of plants and feed on the sap. They drain plants of nutrients, leaving behind unwelcome excrement called honeydew. This provides the perfect environment for black sooty mold to grow, interfering with photosynthesis.

Ladybugs love to eat aphids and can be mail-ordered. Some nurseries sell them as well, although introduced ladybugs will often fly away when their food source dries up. Neem oil, insecticidal soaps, and horticultural oils will also effectively treat an aphid infestation. 

Whitefly

Whiteflies may show up if you’re using too much nitrogen fertilizer. While nitrogen makes your plants larger and healthier, that abundance in foliage will also draw more pests, so it’s important to maintain a balance in fertilizing frequency.

They mostly hang out underneath leaves. Shaking a branch is the easiest way to detect these little bugs, which will fly around when the leaves are jostled. 

Appropriate treatments for whiteflies are neem oil, horticultural oils, and insecticidal soaps. Using these organic treatments in the evening is best to avoid harming pollinating insects.

Thrips

Thrips are another small flying insect that sucks the sap from your plants and leaves honeydew behind. They can also be found feeding on the center of flowers.

These insects are so tiny that they are difficult to detect until they have caused quite a lot of damage. Neem oil and insecticidal soaps will eliminate thrips. The sooty mold caused by honeydew should be wiped away by hand with a soft cloth.

Hawk Moth

The Hawk or Sphinx moth is another insect that lays eggs on Colocasia, and its larvae feed on the plant, chewing up leaves and damaging foliage. These caterpillars are easiest dealt with by manual removal, although insecticides such as BT will eradicate them as well.

Taro Leaf Blight

This disease is specific to Colocasia being grown in Hawaii but can be severe, so it bears mentioning no matter how limited its range is. Phytophthora colocasiae is the fungus responsible for taro leaf blight, and it can kill up to half of the plant roots and up to 95% of leaves if untreated.

Water droplets spread the fungal spores, and the first symptoms are small lesions that rapidly expand and appear to be watersoaked. To treat plants, a copper-based fungicide and remove any affected foliage immediately to stop the spread.

Dasheen Mosaic Disease

Mosaic disease is a virus with origins in India. It specifically affects C. esculenta and is transmitted by aphids. It causes discoloration of the foliage, especially along the leaf veins.

There is no treatment for this disease except to remove the affected plant or plants as quickly as possible to prevent the spread. Aphid management is vital in this case as well. 

Popular Varieties

These unique cultivars will add dazzle to your ornamental gardens or houseplants collection.

‘Blue Hawaii’

	botanical name Colocasia esculenta ‘Blue Hawaii’
	sun requirements Part Sun
	height 5’
	hardiness zones 7-12

This attractive cultivar has two-toned foliage. The bright green, heart-shaped leaves are veined and edged with a deep bluish-purple.

The plant does produce flowers, but they are inconspicuous, and it is typically grown for its showy foliage rather than the flowers. The leaves float about in the breeze atop long, graceful purple stems.  

This variety will be happiest in part sun to full sun, with some protection in the afternoon in warmer climates. It has a lovely tropical appearance and is very low maintenance. This variety grows to about 5’ tall with a 2’ spread.

‘Electric Blue Gecko’

	botanical name Colocasia Gecko ‘Electric Blue’
	sun requirements Part Sun
	height 3’
	hardiness zones 8-11

The Gecko series are compact plants prized for their exceptional color. The plant will stay lower to the ground, reaching about 3’ tall and wide.

‘Electric Blue’ is a uniquely colored variety. The leaves sometimes appear black, deep purple, or metallic blue, depending on how the light hits them. The stems are deep blue, and the plant prefers protection from the afternoon sun. 

‘Illustris’

	botanical name Colocasia esculenta ‘Illustris’
	sun requirements Full Sun to Part Sun
	height 5’
	hardiness zones 8-11

‘Illustris’ is known for its striking foliage, with deep purple to black leaves. The veining and margins of the leaves are electric green, creating a beautiful contrast to the deep velvety color of the foliage.

This variety is award-winning and heat tolerant. It is a nice midsized plant, maturing between 3’-5’, and is resistant to diseases. This variety is known for its easygoing care. It really adds a special touch to a mixed container and looks wonderful in a grouping.

‘Redemption’

	botanical name Colocasia ‘Corede’ PP34,729
	sun requirements Full Sun to Part Sun
	height 6’
	hardiness zones 7-11

This spectacular hybrid is a real showoff in the garden or home. A larger cultivar, ‘Redemption’ has flashy and uniquely colored leaves.

The foundation of the leaves is a deep purple-to-black shade, which is striking on its own. ‘Redemption’ goes one step further with brilliant, hot pink centers and veining. The leaves are glossy and lightly corrugated.

‘Waikiki’

	botanical name Colocasia esculenta ‘Waikiki’
	sun requirements Full Sun to Part Sun
	height 3’
	hardiness zones 8-11

If you want to add some color to your garden, ‘Waikiki’ is the perfect plant for the job. With a clumping habit, this variety reaches a compact 3’ tall and wide, making it more manageable than some larger varieties.

The large leaves are bright green with white centers and bright pink veining. ‘Waikiki’ makes an excellent grouping or focal point.