Devil's tongue (Amorphophallus konjac)
Grow the unique Devil's tongue (Amorphophallus konjac), a cormous perennial with dramatic foliage and a pungent, showy maroon bloom.
Complete Plant Information
Overview
The Amorphophallus konjac, widely known as Devil’s tongue, is a highly distinctive herbaceous, cormous perennial prized both for its architectural foliage and its eccentric bloom. Gardeners are drawn to its robust growth habit and the singular, towering leaf that emerges after the striking flower display fades. This species is native to Asian forest margins and is cultivated globally as a fascinating specimen plant.
When mature, the corm of the Amorphophallus konjac sends up a dramatic inflorescence before the main leaf emerges, featuring a dark, ruffled spathe that emits a potent odor likened to rotting flesh, which serves to attract necessary pollinators. Once blooming ceases, a massive, single, divided leaf emerges, often soaring 4 to 5 feet high, offering bold texture throughout the growing season.
Beyond its ornamental appeal, Amorphophallus konjac holds significant utility, particularly in East Asia where the starch derived from its corms is processed into Konnyaku products. For the temperate gardener, successful cultivation relies on respecting its need for even moisture and avoiding scorching afternoon sun on its emerging foliage.
Fast Facts
- Plant Family: Araceae
- Plant Type: Bulb
- Native Range: China, East Himalaya, Nansei-shoto, Philippines, Thailand, Vietnam
- Hardiness Zones: USDA Zones 6-10
- Size at Maturity:
- Height: 4-5 ft
- Spread: 3-4 ft
- Bloom Time: Seasonal bloomer
- Bloom Description: Maroon to purple-brown
- Sun Exposure: Part shade
- Water Needs: Medium
- Maintenance Level: Medium
How to Grow
Planting the Amorphophallus konjac corm is best done in spring, once all danger of frost has passed and the soil has begun to warm. Locate the corm in fertile, well-draining, humusy loam where it will receive part sun to part shade. This plant strongly dislikes hot, direct afternoon light, especially when the primary leaf is just emerging, as the tender tissues are highly susceptible to scorching.
During the active growing season, maintain evenly moist soil conditions; a “medium” water requirement means avoiding drought but ensuring rapid drainage is paramount. Fertilize consistently throughout the summer months to fuel the large leaf production and corm development. As autumn approaches and the plant begins to die back, gradually reduce water intake.
The corm itself possesses surprising resilience and is hardy down to Zone 6, but both the leaf and the dramatic inflorescence are completely intolerant of frost. Gardeners in the colder end of its range (Zone 6) should treat Amorphophallus konjac as a tuberous perennial, allowing the foliage to die back naturally before digging up and storing the corms dry in a cool, dark location over winter.
Landscape Uses
The impressive size and bold texture of Amorphophallus konjac make it an excellent choice as a unique specimen plant, drawing attention in any garden composition. It performs beautifully when utilized in large containers or pots, allowing gardeners in colder climates to easily relocate the plant for winter protection. In mixed borders, the towering leaf balances softer, lower-growing perennials that prefer similar part shade conditions.
Given its historical use as a vegetable crop yielding edible starch used for noodles and jellies, this plant often sparks conversation about its dual nature as both food source and striking foliage feature. For naturalizing, plant corms in masses within a sheltered woodland edge or under the high canopy of deciduous trees where the soil remains consistently rich and moist, mimicking its native habitat.
Standout Features
Flower Qualities
- Showy
- Fragrant
Noteworthy Characteristics
Amorphophallus konjac, commonly called devil’s tongue, konjaku, konnyaku, or voodoo lily, is a herbaceous, cormous perennial native to forest margins and open thickets in Yunnan Province, China. This species is cultivated around the world as an ornamental and grown throughout East Asia as a food crop. The round, flattened corms can reach up to 11” in diameter and will spread through offsets. The corms will produce a single, highly divided leaf with a pale pink petiole (leaf stem) mottled with olive green splotches; the petiole can reach 4-5’ tall and the leaf blade can reach up to 4’ across. When the corms reach maturity, they will produce an inflorescence before the leaf emerges, consisting of a dense, spike-like spadix and a dark maroon to purple-brown spathe that emits a strong odor of rotten flesh to attract pollinators.
Tolerances
Potential Problems
While generally robust, the primary concerns with Amorphophallus konjac relate to environmental stress rather than persistent pests or diseases. The most common cultural issue is leaf scorch, which occurs when the developing leaf is exposed to intense, hot afternoon sun, making appropriate siting crucial during the early growing season. Overwatering is another threat that can lead to corm rot, especially if the soil lacks sufficient drainage or remains waterlogged during dormancy. Monitor nearby slugs and snails when the new shoots emerge, as tender new growth can be highly attractive to these pests.
Frequently Asked Questions
What hardiness zones is Devil’s tongue suitable for?
The Amorphophallus konjac is quite adaptable, being hardy in USDA Zones 6 through 10.
How large does Devil’s tongue grow?
This perennial typically reaches a height between 4 and 5 feet, with a spread of about 3 to 4 feet when fully grown.
What sun exposure does Devil’s tongue need?
It thrives best when placed in part shade, requiring protection from intense, hot afternoon sun, particularly during the initial leaf emergence.
When does Devil’s tongue bloom?
Amorphophallus konjac is classified as a seasonal bloomer, producing its characteristic maroon to purple-brown spathe flower before the foliage arrives.
Conclusion
The Amorphophallus konjac, or Devil’s tongue, offers unparalleled dramatic impact in the garden through its uniquely structured foliage and unforgettable seasonal bloom. For gardeners seeking bold, architectural interest that integrates function and exotic looks, this cormous perennial is a superb choice. Always check your local climate against USDA Zones 6-10 compatibility and plan for excellent soil drainage before planting your corms this spring.
Companion Planting
When selecting companions for Amorphophallus konjac, focus on plants that share its partial shade needs and appreciation for rich, moist, yet well-draining soil. Large-leafed hostas provide excellent ground cover synergy beneath the towering leaf structure of the Devil’s tongue, complementing its coarse texture with softer, mounding shapes. Ferns, such as Japanese Painted Ferns or Autumn Ferns, thrive in similar conditions and help keep the soil cool and consistently hydrated around the corm. Avoid planting shallow-rooted, sun-loving annuals nearby, as they will compete aggressively for the available moisture and nutrients needed by the developing corm.
Seasonal Care Calendar
Spring marks the excitement, as the unique flower spike of the Amorphophallus konjac erupts well before the foliage; protect this bloom from frost and ensure moderate watering begins as temperatures rise. Summer is the dedication phase: maintain regular fertilization and consistent, medium watering levels while monitoring for leaf scorch caused by afternoon sun exposure. In the fall, after the single massive leaf yellows and collapses, cease watering completely to initiate dormancy; garden managers in colder zones (6-8) should plan to excavate the corms when the ground freezes, storing them safely until spring rebirth.
