The term “Elephant Ear” refers to several plants known for their massive, tropical-looking foliage, most commonly identifying species from two distinct genera: Colocasia and Alocasia. Gardeners often ask if these dramatic plants aggressively colonize the landscape. The answer is yes, they spread, but the rate and method depend heavily on the genus. Understanding the underground architecture of these plants is the first step toward managing their spatial coverage.
The Primary Mechanisms of Horizontal Spread
Elephant Ears are perennial plants that propagate almost entirely through vegetative means. The main body of the plant grows from a specialized, underground storage structure, generally referred to as a corm or tuber. This central structure functions as a food reserve, allowing the plant to survive dormancy and initiate new growth each season.
The primary method of horizontal expansion involves specialized lateral stems that grow away from the main corm. These stems are either rhizomes (underground stems that produce roots and shoots) or stolons (above-ground runners that root at their tips). The growing tips of these structures differentiate into new, independent plants, often called “pups” or offsets. This process allows a single mother plant to rapidly establish a dense colony of clones.
How Spreading Habits Differ by Plant Type
The genus Colocasia, often called Taro, is the primary source of aggressive spreading concerns. These plants are prolific runners, utilizing long, slender stolons that quickly extend outward from the main plant, sometimes traveling several feet in a single season. Offsets developing at the end of these stolons quickly root and establish their own network of underground rhizomes. This vigorous growth habit results in a rapidly expanding patch of foliage, making Colocasia challenging to contain.
In contrast, Alocasia species, sometimes known as Upright Elephant Ears, exhibit a much more contained, clumping growth habit. While they also grow from a tuberous base, they do not produce the long, aggressive stolons characteristic of Colocasia. Instead, Alocasia spreads slowly by generating new offsets, or cormels, directly from the sides of the main tuber. These cormels remain close to the mother plant, leading to a slowly thickening clump rather than rapid colonization.
Environmental preference also influences spread. Colocasia thrives in extremely moist or boggy conditions, which encourages the rapid development of its running structures. Alocasia generally prefers well-drained soil, which naturally limits the aggressive underground movement often associated with its water-loving relative.
Managing and Containing Aggressive Growth
For gardeners dealing with the aggressive spread of Colocasia, physical barriers offer an effective solution. Install a root barrier, such as thick plastic sheeting or metal edging, buried 18 to 24 inches deep around the planting area. This successfully blocks the horizontal movement of stolons and rhizomes. The barrier must fully encircle the planting site to prevent runners from escaping.
Regular division is another manual method to manage population density and prevent runaway growth. For spreading varieties, plan to dig up and divide the clumps every two to three years, preferably during the dormant season. When dividing, carefully remove the main clump and sever all attached stolons and cormels. Ensure no small pieces of tuber remain in the ground, as even tiny fragments can sprout into new plants.
Growing Elephant Ears in containers is the most straightforward method for complete containment, especially for running Colocasia varieties. The restricted space naturally limits the plant’s ability to send out long runners. If you prefer the look of in-ground planting, sink a large container, such as a sturdy nursery pot, directly into the soil. This technique maintains a physical boundary against unwanted horizontal expansion while providing the aesthetic of a garden-planted specimen.