Amorphophallus konjac

RHS Plant Profile

konjaku

RHS

Other common names

konnyaku, devil's tongue, snake palm, umbrella arum

Synonyms

Amorphophallus rivieri

Conservatory Greenhouse Bulbs

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A tuberous perennial producing a single flower in summer consisting of a shiny, red-purple spathe and tall, paddle-like, brown spadix. It has an unpleasant smell to attract pollinating flies.After the flower has faded a single, highly divided leaf appears with bright green leaflets and a stout, olive-green stem with white markings

Position

Partial shade

Soil Types

Loam

Max Height

1-1.5 metres

Max Spread

1-1.5 metres

Size

Time to Maturity: 5–10 years
Max Spread: 1-1.5 metres
Max Height: 1-1.5 metres

Growing Conditions

Loam

Moisture: Moist but well–drained
pH: Acid or Alkaline or Neutral

Position

Partial shade

Aspect: West–facing or East–facing
Exposure: Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

H1A: under glass all year (>15C)
H1B: can be grown outside in the summer (10 - 15)
H1C: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20): H1B

Colour & Scent

Fragrance Flower

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Araceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Columnar upright
Potentially harmful: Harmful if eatenskin/eye irritant. Wear gloves and other protective equipment when handling Pets: Harmful if eatenskin/eye irritant - see the HTA guide to potentially harmful plants for further information and useful contact numbers
Genus: Amorphophallus are perennials with corm-like rhizomes and huge, deeply-lobed leaves. The flowers are composed of a purple-red to greenish-white spathe, often unpleasantly-scented, and a central spadix
Name Status: Correct
Plant Range: Indonesia to Japan

How to Grow

Cultivation

Plant dormant tubers 10cm deep in late winter or early spring in a large container of peat-free, loam-based potting compost. Grow in filtered light, water and feed while in active growth, and overwinter in warm, barely moist conditions

Propagation

Separate offsets when dormant, or propagate by seed sown in heat in autumn or early spring

Suggested planting locations and garden types

Patio and container plants
Sub-tropical

Pruning

No pruning required

Pests

Generally pest-free

Diseases

Generally disease-free