Aconitum chasmanthum

RHS Plant Profile

open-flowered monk's hood

Synonyms

Aconitum violaceum var. robustum

Herbaceous Perennial

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Upright, clump-forming, herbaceous perennial, producing panicles of bright purple-blue, hooded flowers. These appear in late summer and autumn on stems up to 1.5m high, above dark green, leathery, palmate to deeply-divided, lobed foliage

Position

Full sun, Partial shade

Soil Types

Clay, Loam

Max Height

1-1.5 metres

Max Spread

0.5-1 metres

Size

Time to Maturity: 2–5 years
Max Spread: 0.5-1 metres
Max Height: 1-1.5 metres

Growing Conditions

Clay Loam

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

Position

Full sun Partial shade

Aspect: East–facing or South–facing or West–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): H7

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Ranunculaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Clump forming
Potentially harmful: TOXIC if eatenavoid skin contact. Wear gloves and other protective equipment when handling. Pets: TOXIC if eatenavoid 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

How to Grow

Cultivation

Best grown in moisture-retentive fertile soil in partial shade but sun and most soils are tolerated. Staking may be necessary. See staking perennials for further advice

Propagation

Propagate by division every third year in autumn or late winter to maintain vigour, although plants can be slow to re-establish

Suggested planting locations and garden types

Cottage and informal garden
Wildlife gardens
Flower borders and beds

Pruning

Tall stems can be pruned down later in autumn when flowering is finished

Pests

May be susceptible to aphids

Diseases

May be susceptible to fungal stem rot and Verticillium wilt