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Herbaceous Perennial

Aster thomsonii
  • RHS Plants for pollinators

Thomson's aster

A clump-forming perennial, to 1m tall, with oval, toothed leaves, up to 10cm long, on hairy stems. Flowerheads, up to 5cm across, comprising lavender-blue rays and a central yellow disk, are held on slender branches from late summer into autumn

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Size
Ultimate height
0.5–1 metres
Time to ultimate height
2–5 years
Ultimate spread
0.1–0.5 metres
Growing conditions
Chalk
Loam
Sand
Moisture
Moist but well–drained, Well–drained
pH
Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring
Summer Blue Purple Green
Autumn Blue Purple Green
Winter
Position
  • Full sun
Aspect

East–facing or South–facing or West–facing

Exposure
Exposed or Sheltered
Hardiness
H6
Botanical details
Family
Asteraceae
Native to GB / Ireland
No
Foliage
Deciduous
Habit
Bushy
Genus

Aster can be perennials, annuals or subshrubs, mostly with narrow leaves, and solitary or clustered, daisy-like flowers

Name status

Correct

How to grow

Cultivation

Grows best in full sun in a well-drained, alkaline soil with moisture in the spring and summer

Propagation

Propagate by division

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

Cut back in late autumn

Pests

May be susceptible to Tarsonemid mite

Diseases

May be affected by Verticillium wilt and grey moulds

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