Symphyotrichum × salignum

RHS Plant Profile

common Michaelmas daisy

Synonyms

Aster × salignus

Herbaceous Perennial

A tall, bushy perennial, to around 1.2m high, with rough, narrow, lance-shaped green leaves. Clusters of small, daisy-like flowers to 2cm across, with white petals and yellow centres, are borne on branching stems in late summer and autumn

Position

Full sun

Soil Types

Clay, Loam, Sand

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 Sand

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

Position

Full sun

Aspect: South–facing or West–facing
Exposure: Exposed or 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: 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
Plant Range: NC USA

How to Grow

Cultivation

Grow in a sunny spot in fertile, moisture-retentive soil; add mulch after cutting back in autumn. Divide every third year to retain vigour and flower quality. Stake tall plants in early spring, see staking perennials. See aster cultivation for further advice

Propagation

Propagate by seed or by division in spring, replanting only vigorous young shoots

Suggested planting locations and garden types

Cottage and informal garden
Prairie planting
Wildflower meadow
Wildlife gardens
Flower borders and beds

Pruning

Cut stems close to the ground in late autumn

Pests

May be susceptible to leaf and bud eelworm, aphids, slugs and snails

Diseases

May be susceptible to Fusarium wilt, Powdery mildews, leaf spots and grey moulds