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Herbaceous Perennial

Ageratina altissima
  • RHS Plants for pollinators

white snakeroot

A tall herbaceous perennial to about 1.7m with brown stems and grey-green, nettle like leaves. Umbel-like clusters of small, white, long-lived flowers appear in summer and early autumn

Other common names
deerwort
hardy age
see moremilk ipecac
mist flower
nettle-leaved hemp agrimony
rich weed
white sanicle
Synonyms
Eupatorium urticifolium
Eupatorium ageratoides
see moreEupatorium rugosum
Eupatorium album misapplied
Eupatorium fraseri misapplied
Eupatorium rugosum album
Ageratum altissimum
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Size
Ultimate height
1.5–2.5 metres
Time to ultimate height
2–5 years
Ultimate spread
0.5–1 metres
Growing conditions
Chalk
Clay
Loam
Moisture
Moist but well–drained, Poorly–drained
pH
Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Green Grey Silver
Summer White Green Grey Silver
Autumn White Green Grey Silver
Winter
Position
  • Partial shade
Aspect

East–facing or West–facing

Exposure
Sheltered
Hardiness
H5
Botanical details
Family
Asteraceae
Native to the UK
No
Foliage
Deciduous
Habit
Bushy
Genus

Ageratina are shrubs or herbaceous perennials with opposite leaves and small tubular flowers borne in corymbs

Name status

Correct

Plant range
North America

How to grow

Cultivation

The ideal site is a moist, alkaline soil in partial shade; frost may damage new shoots

Propagation

Propagate by seed or division, in spring

Suggested planting locations and garden types
  • Wildlife gardens
  • Cottage and informal garden
  • Flower borders and beds
Pruning

Cut back faded flower stems to base

Pests

May be susceptible to slugs and aphids

Diseases

Generally disease-free

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