Not the plant you're looking for? Search over 300,000 plants
Herbaceous PerennialSynonym

Aster oolentangiensis
  • RHS Plants for pollinators

sky blue aster

Clump-forming perennial with slender flowering stems about 90cm in height with lance to heart-shaped rough-hairy, mid-green leaves. From late summer to autumn bears spreading clusters of daisy-like pale lavender blue flowerheads to 2.5cm across, with yellow centres

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

East–facing or South–facing or West–facing

Exposure
Exposed or Sheltered
Hardiness
H7
Botanical details
Family
Asteraceae
Native to GB / Ireland
No
Foliage
Deciduous
Habit
Clump forming
Genus

Symphyotrichum includes around 90 species of annuals, biennials and perennials, mostly spread through the Americas, that were formerly included within the genus Aster. Leaves are simple, lance-shaped and entire, but it is their daisy-like flowerheads that they are grown for; central disc florets are typically yellow, surrounded by strap-shaped ray florets in shades of pink, blue, purple or white

Name status

Correct

How to grow

Cultivation

Grow in moderately fertile, moist but well-drained soil in full sun or light shade. Stake tall plants in early spring, see staking perennials. See aster cultivation for further advice

Propagation

Propagate by division in spring or root softwood basal cuttings in spring; division can be carried out every third year to maintain vigour

Suggested planting locations and garden types
  • Coastal
  • Cottage and informal garden
  • Gravel garden
  • Prairie planting
  • Wildflower meadow
  • Wildlife gardens
  • Cut flowers
  • Flower borders and beds
Pruning

Cut stems close to the ground in late autumn

Pests

May be susceptible to leaf and bud eelworms, slugs and snails

Diseases

May be susceptible to Verticillium wilt, Powdery mildews and grey moulds

Get involved

The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.