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Herbaceous Perennial

Aconitum japonicum

Japanese monk's hood

A clump-forming, upright perennial to around 1m tall with deeply divided, glossy dark green leaves to 16cm long. Panicles of hooded, deep blue flowers are borne in late summer

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Ultimate height

0.5–1 metres

Time to ultimate height

2–5 years

Ultimate spread

0.1–0.5 metres

Clay

Loam

Moisture

Moist but well–drained

pH

Acid, Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full sun
Partial shade

Aspect

West–facing or East–facing or North–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)

Botanical details

Family: Ranunculaceae
Native to GB / Ireland: No
Foliage: Deciduous
Habit: Clump forming
Potentially harmful: TOXIC if eaten, avoid skin contact. Wear gloves and other protective equipment when handling. Pets: TOXIC if eaten, avoid skin contact - see the HTA guide to potentially harmful plants for further information and useful contact numbers
Genus: Aconitum can be herbaceous perennials or biennials with lobed leaves and racemes or panicles of showy, hooded flowers
Name status: Correct
Plant range: Japan

How to grow

Cultivation

Best grown in moisture-retentive fertile soil in partial shade but sun and most soils are tolerated

Propagation

Propagate by division in autumn or late winter to maintain vigour, although plants can be slow to re-establish. Use gloves when handling plants

Suggested planting locations and garden types

Cottage and informal garden
Wildlife gardens
Flower borders and beds

Pruning

No pruning required except cutting back dead stems; use protective gloves

Pests

May be susceptible to aphids

Diseases

May be susceptible to fungal stem rot, powdery mildews, and Verticillium wilt

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