The Amorphophallus konjac, known as Konjac, Voodoo Lily, and Devil’s Tongue, is a captivating tuberous perennial. Native to subtropical and tropical East Asia, its unusual growth habit and striking appearance make it a fascinating plant for both indoor and garden cultivators.
Understanding the Konjac Life Cycle
The Amorphophallus konjac life cycle includes active growth, dormancy, and a rare flowering phase. During the active growing season (typically spring and summer), the plant produces a single, large, intricately divided leaf. As autumn approaches, the leaf yellows and dies back, signaling dormancy. A mature corm may produce a large bloom before the leaf emerges, though this is not an annual event.
Care During Active Growth
Light
Amorphophallus konjac thrives in bright, indirect light. It can tolerate some direct morning sun, but harsh afternoon sunlight can scorch its foliage. Outdoors, choose a spot with dappled shade or morning sun and afternoon shade. Indoors, place it near a window providing ample brightness without direct, unfiltered sun.
Watering
During active growth, Amorphophallus konjac needs consistent moisture. Keep the soil evenly moist but never waterlogged to prevent corm rot. Allow the top inch or two of soil to dry slightly between waterings. As the plant matures, its water requirements may increase due to a larger root system and its foliage mass.
Soil and Potting
A well-draining, humus-rich, and fertile potting mix is suitable for Amorphophallus konjac. An all-purpose potting mix amended with perlite is recommended to enhance drainage. Plant the corm deeply, about twice its height, as roots emerge from the top of the tuber. Choose a pot at least twice the corm’s diameter for ample space for root development and corm expansion.
Temperature and Humidity
Amorphophallus konjac prefers warm temperatures during its growing season, ideally 18-26°C (64-79°F). Protect it from prolonged temperatures below 10°C (50°F). Moderate humidity (50-60%) is appreciated and can be maintained through misting, especially in drier indoor environments.
Fertilization
This plant is a heavy feeder during its active growth. Apply a balanced fertilizer (e.g., 10-10-10 N-P-K) every 4-6 weeks to support robust foliage development. Fertilizers higher in phosphate can encourage healthy corm growth and flowering. Stop fertilizing when the foliage yellows and dies back, signaling dormancy.
Care During Dormancy
As the active growing season concludes (typically late summer or fall), the Amorphophallus konjac leaf yellows and collapses, indicating dormancy. Cease all watering once the leaf dies back to prevent corm rot. The corm can be left in its pot with dry medium or lifted and stored.
If storing the corm out of its pot, gently dig it up after the foliage has browned. Clean off any remaining soil and store the corm in a cool, dark, dry location. Ideal storage temperatures are 5-10°C (40-50°F). Keeping the corm dry is crucial to prevent fungal issues.
Common Challenges and Troubleshooting
Yellowing leaves outside dormancy can indicate improper watering, nutrient deficiencies, or insufficient light. Both overwatering (leading to root suffocation) and underwatering (hindering nutrient transport) can cause yellowing. Ensuring consistent, appropriate watering and checking for nutrient imbalances can help resolve this.
Lack of flowering often occurs if the corm is not mature enough, typically requiring about five years of growth. Environmental stress or inadequate care can also delay blooming. Pest infestations (e.g., mealybugs, scale insects) can lead to stunted growth and discolored foliage. Fungal diseases like soft rot or dark blotch can be managed by ensuring good drainage and airflow, and with fungicides in severe cases.
Propagation
Amorphophallus konjac can be propagated by separating cormlets, which are smaller offsets that form around the main corm. The best time for this is late winter or early spring, while the plant is dormant. Carefully unearth the main corm, avoiding damage.
Gently detach cormlets from the parent corm, ensuring each offset has some roots attached if possible. Plant these separated cormlets individually in pots with well-draining soil. Adequate moisture and warmth will encourage new plants to sprout and begin their own growth cycle.