Colocasia gigantea
It seems I need to add to this post. Colocasia Gigantea is now known by science as Leucocasia gigantea. It has been removed from the Colocasia group into it’s own section.

Colocasia Gigantea (Thailand Strain) is a unique and large growing plant in the Araceae family (commonly called Aroids). The family consist of many unusual plants including Amorphophallus (voodoo lilies), Alocasia and Colocasia (elephant ears) and Spathiphyllum (peace lilys). 

Colocaisa Gigantea is found native in tropical parts of Asia such as China, Thailand, and Borneo. The petioles (stems) are used by natives as a food source. Villagers with poor soil use this plant to feed livestock. Colocasia gigantea (Thialand Strain) made its way to the states in 2003 when seeds were brought back by Alan Galloway and Petra Schmidt from an expedition to Thailand. Gigantea has gone from an unknown plant in 2003 this to being asked for by name by the general public in 2010. 

Colocasia Gigantea (Thailand Strain) Growth Habit

Gigantea has already made an impact in the horticulture world and many gardens with its overall size demanding attention. Colocasia Gigantea towers over other Colocasia species in every way from leaf size to height. Below I will give details on each aspect of the plant as I have grown it.
Growth Rate
Colocasia Gigantea is one of the fastest growing plants I have seen.. In the ground, I have seen 4 inch plants reach 8 to 10 feet tall in one season, which in Kentucky is around 5 to 6 months.

The mature foliage of Gigantea can be 4 to 5 feet in length and 2 to 4 feet in width. The veins and mid-veins are much larger and pronounced than most species. The leaves are a light aqua green to glaucum color. The petioles (stems) are also this light green color and have a white powdery substance on them.

The base of the plant can be extremely large sometimes measuring 1 foot or larger across. During the summer, I often find water held in the cupped bases of the petioles. Small tubers can be produced at the base of the plant and sucker plants are not uncommon on mature plants. A few times I have noticed small runners at the base, usually running only a few inches then producing a small plant at the tip. This trait is not common but has been observed on a few mature plants. This could be more typical in a different environment. When a mature plant is dug a large root mass is found with many white roots. This plant rarely produces a large tuber (bulb) at the end of the season, but if dug up and stressed, the plant can make a large starchy tuber.

Flowers and Seeds
The flowers like most parts of Gigantea are unique. The flowers will be produced after you see what is commonly called a flag leaf. This unusual thin foliage spike is formed then the older petiole (stem) will push out a cluster of 6 flowers. The flowers are held in a fan shape and usually open one after another for the next 6 days. The flowers are 1 foot tall or larger on mature plants with white spath and spadix. The flowers will open and produce a unique sweet smelling fruit scent. The following day the spadix will drop white pollen.
Colocasia gigantea Flower

The fruit of the Gigantea are held in the base of the inflorescence after the spath and spadix have fallen off. Once ripened, the green pod will fall away and inside will be light yellow to duel orange berries. Each berry can contain multiple seeds, up to 20 or more per berry. The berries are full of a sugary substance that once squished is very slimy. The sugar is likely to attract animals so that the berries are eaten and deposited by animals in the tropical rain forest. Seeds are small, about the size of sesame seeds or smaller. If seeds are examined closely parallel ridges down each seed can be seen.
Colocasia Gigantea Seeds

Colocasia Gigantea Care

I have seen Colocasia Gigantea (Thailand Strain) grown in many different situations, regions and climates. The following are what I feel is the best environment to grow it in for it in our climate and zone.
Wind: The largest plants I have seen have been somehow protected from strong winds. The plant can grow in an area with wind but it would be shorter, stout in size with torn leaves, if wind is harsh.

Sunlight: I have found that Colocasia Gigantea prefers only half a day of sun. It does not matter if it is 4 to 6 hours of morning or afternoon sun. If the plant receives to little sun the your plant is stunted. If the plant is in full sun you can reach a decent size but not on large as some pictured here.

Soil: I have found that regular garden soil, organic soil, compost and Kentucky clay works well for growing Gigantea (Thailand Strain). A good average soil is all the plant needs, too much adding and you may burn your roots and cause root rot.

Watering: Gigantea (Thailand Strain) can handle lots of water but the soil should be allowed to drain quickly. Gigantea (Thailand Strain) has shown stress if grown aquatically or with wet feet. It may do well in other climates as a bog grower but here I find the roots, which are fairly large and not very fibrous, easily drown and rot. This can lead to a mess of problems for your plant.

Feeding: Gigantea (Thailand Strain) can handle regular feeding. The best results I have seen is with a liquid feed. Gigantea plants should not be feed unless they are 1 to 3 feet tall and performing well. The feed should be given as instructed on the fertilizer container. I use fertilizers with numbers 12-12-12 or 10-10-10, these are often used for vegetable plants. Another fertilizer I often use is Epson salts or Magnesium sulfate. Magnesium sulfate is a good additive to help darken leaves and toughen the plant, use 1 tablespoon per gallon of water. The best time to fertilize your plant is when the plant has been watered or if it has rained the day before.

Greenhouse Production
In production we have grown small plants in 288 or 72 cell trays. Small ½ inch plants have been able to fill 4 ½ inch pots in 4 to 6 weeks with regular liquid feed. A 3 to5 gallon pots can be grown out in just a few weeks if bumped up from the 4 ½ inch pot.

Several ordinary pest can attack Colocasia species including Colocasia Gigantea. These most common include spider mites, aphid or mealy bugs . Spider mites look like white powder on the back or top of the foliage, usually starting in the center of the leaf. Aphids are small green to brown insects that can be seen with the naked eye. Mealy bugs may be found from time to time but are also easily treated. I personally use Orthene for these pest. I found that most soaps and oils will cause leaf burn on the plants especially if the temps are high or if the light is intense. I would recommend testing your pesticide on a single leaf or plant to be sure it does not damage your stock or your only plant.

Colocasia Gigantea Clones
There are two Colocasia Gigantea clones that are considered by science to be the same species but they are distinctly different than one another in habit and growth. The one shown and noted above is commonly called Colocasia Gigantea (Thailand Strain) the other clone I commonly refer to as Colocasia Gigantea (Common Strain). This form was more widely known years ago and is more commonly used for food and production in tropical Asia. It has several key differences than that of the Thailand Strain. One difference is that it rarely reaches the same height and size of Thailand Strain. The largest Colocasia Gigantea (Common Strain) plant I have grown was 5 to 6 feet tall. The leaves are also smaller in size, 2 to 3 feet long and wide. One of the sure ways to tell the two plants apart is the odd growths under the foliage of the Colocasia Gigantea (Common strain). Under each mature leaf it has an odd mutation of what looks to be leaf like structures between the veins. I have also found that the Common Strain rarely flowers. I was able to get flowers 1 time by having the plant grown in hydroponic type environment. The flowers were identical to the Thailand Strain but smaller and did not produce pollen or fruit. Some other very notable differences is the small tubers produce by the Colocasia Gigantea (Common Strain). This plant produces multiple plants and is much more productive in producing tubers. This tuber production may also explain why this plant is much more cold tolerant than the Thailand Strain. I have over wintered the Common strain multiple times in the ground here in Kentucky with little to no protection. The same cannot be said for the Thailand Strain which seems to be hardy to zone 8 and higher. Colocasia Gigantea (Common Strain) has grown in aquatic or hydroponic environment without rotting. Heavily misted plants produced runners over the top of the soil this was not common for regular ground production.

Over all Colocasia Gigantea (Thailand Strain) has shown to be a great addition to back yard gardens, large containers and tropical theme displays. This plant is making a dramatic impact on the landscape and the people that grow them. If you have not yet grown a Colocasia Gigantea (Thailand Strain) I would recommend it for the professional to the novice growers.
Buying Colocasia Gigantea 
At Brians Botanicals we like to grow and sell many of the plants we love. Colocasia Gigantea is one of my personal favorites. It is just a huge fast growing plant and I always enjoy having them to offer on our website. I recommend getting plants that are not from Tissue Culture for this species. Most hybrids and varieties are mostly sold this way and it works. From past experiences I have found seed grown stock to get larger and grow faster than TC material. My plants of Colocasia Gigantea (Thailand Giant) are grown from seed each year. The other clone Colocasia Gigantea common form is grown from pups off of the mother plants. 
 Our plants are sold in 4 to 4 1/2 inch pots and plants usually are 8 to 12 inches tall. You can find out plants at the following link.