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Herbaceous Perennial

Arisaema costatum

ribbed cobra lily

A tuberous perennial, to about 60cm with large three-lobed shiny, dark green leaves, to 40cm long with distinctive ridged veins and purple margins. The leaves emerge in early summer before the flowers which last throughout the summer. Flowers comprise of a deep purple hooded spathe with white stripes, and a long narrow twisted spadix.

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Size
Ultimate height
0.5–1 metres
Time to ultimate height
5–10 years
Ultimate spread
0.5–1 metres
Growing conditions
Loam
Sand
Moisture
Moist but well–drained
pH
Acid, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring
Summer Purple White Green Purple
Autumn Green Purple Red
Winter
Position
  • Partial shade
Aspect

East–facing or North–facing or West–facing

Exposure
Sheltered
Hardiness
H4
Botanical details
Family
Araceae
Native to GB / Ireland
No
Foliage
Deciduous
Habit
Columnar upright
Potentially harmful
Humans/Pets: Harmful if eaten, skin/eye irritant. Wear gloves and other protective equipment when handling For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus

Arisaema are mostly tuberous perennials usually with palmately lobed leaves, and distinctive tubular, hooded spathes within which the tiny true flowers are clustered at the base of the club-like or filamentous spadix, followed by a spike of red berries

Name status

Correct

Plant range
Himalaya to S Tibet

How to grow

Cultivation

Plant the tubers 20cm deep in winter or spring, into moist but well-drained, humus-rich soil in a cool, partially shaded site. In colder regions it may need winter protection, mulch with well-rotted leaf mould for insulation. Tubers must not dry out while dormant but avoid excessive winter wet.

Propagation

Propagate by seed sown in containers in a cold frame in autumn or spring. Offsets may be removed in late summer

Suggested planting locations and garden types
  • Cottage and informal garden
  • Patio and container plants
  • City and courtyard gardens
  • Underplanting of roses and shrubs
  • Flower borders and beds
Pruning

No pruning required

Pests

May be susceptible to slugs and vine weevil

Diseases

Generally disease-free

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