The “Labyrinth Plant,” scientifically known as Amorphophallus konjac, is a perennial also called Devil’s Tongue, Konjac, or Voodoo Lily. Native to warm subtropical and tropical East Asia, including China, Japan, and Indonesia, its allure stems from its unusual growth cycle and distinctive appearance, particularly its underground corm structure.
Distinctive Features
The Amorphophallus konjac is characterized by its underground corm, often incorrectly referred to as a bulb, which is a tuber that can reach up to 1 foot in diameter. This corm stores nutrients, shrinking as the plant develops its large leaf and then growing a new, larger corm during the active season.
A single, large, highly divided leaf emerges from the corm, spanning up to 4 feet across and reaching 4 to 6 feet tall. Its stalk, or petiole, displays a mottled pinkish-gray and olive-green pattern, giving it a unique visual appeal. The leaf is intricately dissected into numerous smaller leaflets, creating an umbrella-like or tree-like effect.
Before the leaf appears, mature corms produce a remarkable flower structure in late winter or early spring. This inflorescence features a large, shiny brown-purple to maroon ruffled spathe surrounding a central spadix. When in bloom, the flower emits a strong odor reminiscent of rotting flesh, attracting pollinators like carrion flies and midges. This scent typically lasts for a day or two.
Cultivation Essentials
Successful cultivation of Amorphophallus konjac requires specific conditions during its active growth. The plant thrives in well-drained, humus-rich, fertile soil. A suitable potting mix includes an all-purpose mix amended with perlite or a blend of perlite, well-rotted leaf compost, and multi-purpose compost. Avoid clay soils, especially in cold, wet winters, as they can cause corm rot.
Plant the corm approximately twice its height deep, as roots emerge from the top. For example, a 2-inch corm should be planted about 4 inches deep. The plant prefers bright, indirect light or dappled shade, particularly avoiding harsh, hot afternoon sun which can scorch the emerging leaf. While it can tolerate lower light levels, optimal growth occurs with sufficient indirect light.
During the growing season, maintain consistent soil moisture, keeping it evenly moist but not waterlogged. It can even tolerate standing water, making it suitable for water gardens. Ideal growing temperatures range from 68 to 77°F (20-25°C), with a minimum of 60°F (16°C) during its active period. Higher humidity (50-60% or more) supports optimal growth, mirroring its native tropical environment. Fertilize regularly throughout the growing season with a balanced liquid fertilizer or one high in phosphorus, applied every one to two weeks, or use a slow-release product tri-annually.
The Dormancy Cycle
A defining characteristic of Amorphophallus konjac is its annual dormancy cycle. The leaf typically lasts one growing season, yellowing and senescing in late summer or fall, signaling the plant’s resting phase. Do not cut the leaf until it has completely turned brown, allowing the corm to reabsorb nutrients.
Once the foliage dies back and the plant enters dormancy, stop watering completely. The corm can remain in its pot in dry growing medium or be removed and stored. If storing, clean the corm of soil and place it in a dry medium like peat moss or sawdust, ensuring good airflow and that corms do not touch to prevent rot. Store corms in a cool, dark location, ideally between 40-50°F (5-10°C), though they can tolerate slightly warmer room temperatures if air circulation is good. This dry, dormant period is essential for the plant’s health and future growth and blooming.
Propagation Methods
Propagation of the labyrinth plant is primarily achieved through corm division. Amorphophallus konjac readily produces offsets, also known as cormels or “pups,” which are smaller tubers forming around the parent corm. These offsets can be separated from the main corm, ideally in spring, when new growth begins to show.
To propagate, carefully unpot the dormant corm and gently detach any cormlets. Plant these smaller corms into their own pots using the same well-draining, fertile soil mixture as mature plants. Ensure pots are appropriately sized, at least twice the corm’s diameter, to allow for root development and future corm expansion. While seed propagation is possible, it is less common and results in much slower growth.
Troubleshooting Guide
Common issues when cultivating Amorphophallus konjac often stem from improper care. Corm rot is a frequent problem, primarily caused by overwatering, especially during dormancy, or by planting in heavy, poorly draining soil. Preventing this requires consistent, but not excessive, moisture during the growing season and completely dry conditions during dormancy.
Lack of flowering can occur if the corm is not mature enough, typically taking about three years to reach blooming size (around grapefruit-sized or larger). Insufficient nutrients, particularly phosphorus, can also hinder flower development, as this element supports tuber growth. Pests are generally not a significant problem, though mealybugs or scale insects can occasionally occur. Providing appropriate growing conditions and proper dormancy care are the best preventative measures for a healthy plant.