A true colossus, Colocasia gigantea is an elephant ear that reaches extraordinary sizes. The leaves of the ‘Thailand Giant’ strain may grow to be 5 feet long by 4 wide. Inflorescences appear on larger plants in autumn in groups. These can grow in shallow water and are extremely intolerant of drought.
Colocasia gigantea (Taro, Dasheen)
Deciduous: no in tropical areas, dies back and returns in spring where winters do not drop below 20 degrees Fahrenheit
Hardiness Zones: 8-11
Height: To 3 meters (9 feet) tall in temperate regions, supposedly ‘Thailand Giant’ can reach 6 meters (20 feet) tall in its native habitat with leaves to 1.5 meters long by 1.2 meters wide (5 feet long by 4 feet wide).
Diameter: to roughly 5 meters (16 feet) across overall
Growth Rate: fast
Root System: fibrous
Subspecies: ‘Thailand Giant’ (ENORMOUS)
Tolerates: herbivores (rabbits, deer)
Problems (major): none
Problems (minor): Dry soils significantly harm health, may kill plants (especially younger or weakened plants).
Poisonous: The entire plant contains Calcium Oxalate crystals, which can cause pain to the throat and mouth if ingested. May be edible once very thoroughly
Soil requirements: requires consistently moist soils with good drainage, pH 5.6-7.5, greatly appreciates fertilizer
Air requirements: grows best in high humidity
Watering requirement: moderate to high, survives in shallow standing water
Sun requirement: full sun to part-shade
Leaf shape: heart-shaped, petiole attached at the intersection of the “Y”-shaped veins, basal
Leaf size: enormous, petioles to 2.5 meters (8 feet) long
Stem: none, petioles only
Flowering structure: inflorescence with a green peduncle, green spathe to 60 centimeters (24 inches) long, white spadix, frequently occur in small groups of 5 to 13
side by side, rise from leaf axil
Flowering frequency: somewhat common once large enough, July to October, naturally pollinated by beetles or people
Fruits: Inflorescences give way to somewhat cone-shaped, yellowish seed pods with oblong berries. The seeds are tiny, black, similar to tomato seeds.
These, like other Colocasia, may reproduce by dividing bulbs.
These are sometimes planted in gardens as colossal ornamentals. In tropical areas (especially ‘Thailand Giant’), these grow to spectacular sizes at fast rates.