Aster lateriflorus 'Horizontalis' (Calico Aster) — Clump-forming, upright to bushy

Overview

Aster lateriflorus 'Horizontalis' is a clump-forming, upright to bushy perennial in the genus Aster, part of the Asteraceae family, with deciduous; simple, often narrow and roughly textured foliage. Aster lateriflorus 'Horizontalis' grows best in full sun, and tolerates fertile loam; avoid thin and dry soils soils and neutral to slightly alkaline pH. Its UK hardiness is rated H6–H7. Suggested uses include borders, wildlife gardens and naturalized areas. It is native to Northeastern U.S.A., Eastern Canada, North-Central U.S.A. and Southeastern U.S.A..

About

A clump-forming perennial in the Asteraceae, Aster lateriflorus 'Horizontalis' produces a late-summer to autumn display of small flower heads from August to October. It has deciduous, simple leaves that are often narrow with a rough texture and an upright, well-branched habit. Plant in fertile loam that stays moist but drains freely, and position in full sun on a south-, east- or west-facing site. It suits exposed or sheltered locations and withstands very cold UK winters (H6–H7).

Wikipedia contributors, CC BY-SA 4.0 — Symphyotrichum lateriflorum

About the genus

Aster is a genus of perennial flowering plants in the family Asteraceae. Its circumscription has been narrowed, and it now encompasses around 170 species, all but one of which are restricted to Eurasia; many species formerly in Aster are now in other genera of the tribe Astereae. Aster amellus is the type species of the genus and the family Asteraceae.

Wikipedia contributors, "Aster (genus)", CC BY-SA 4.0 — Aster (genus)

In the garden

Aster lateriflorus 'Horizontalis' is a North American native, coming from regions including the north-eastern and central United States and eastern Canada. It is a clump-forming, upright perennial in the Asteraceae that develops multiple stems and produces its succession of flowers from August to October. Mature plants are perennial and herbaceous, dying back after the season in colder areas before re-emerging the following year. Give this cultivar a sunny situation and a fertile, loamy soil that retains moisture without becoming waterlogged; avoid thin, dry soils. It prefers neutral to slightly alkaline soil pH and will tolerate both exposed and sheltered aspects on south, east or west facing slopes. In UK terms it ranges from very hardy (H6) to fully hardy (H7), and it also corresponds to USDA zones 4–8. Use Aster lateriflorus 'Horizontalis' in mixed borders, wildlife-focused plantings or naturalised areas where late-season flowering is wanted, and plant in groups for better visual impact. Flowering runs from August to October, making it a useful source of late-season presence in herbaceous schemes.

Growing conditions

Best soil and position for Aster

Sunlight: Full sun
Soil type: Fertile loam; avoid thin, dry soils
Soil pH: Neutral to slightly alkaline
Soil moisture: Moist but well drained
Aspect: South, east or west facing
Exposure: Exposed or sheltered
UK hardiness: H6–H7

Plant details

Aster lateriflorus 'Horizontalis' size, habit and characteristics

Plant type: Perennial
Habit: Clump-forming, upright to bushy
Foliage: Deciduous; simple, often narrow and roughly textured
Suggested uses: Borders, wildlife gardens, naturalized areas
Native to: Northeastern U.S.A., Eastern Canada, North-Central U.S.A., Southeastern U.S.A.

Care notes

Pruning and caring for Aster lateriflorus 'Horizontalis'

Cultivation: Plant in an open, airy position — crowding is what brings on mildew. Divide every second or third year to maintain vigour, and pinch or Chelsea-chop the taller kinds in late spring to reduce the need for staking.
Pruning: Deadhead to prolong the display, then cut stems to the base after flowering, or leave them standing through winter for structure and wildlife.
Propagation: Divide in spring, replanting only the vigorous outer growth. Basal cuttings taken in spring root readily.
Pest resistance: Slugs may take young shoots in spring; otherwise generally trouble-free.
Disease resistance: Powdery mildew is the main weakness, especially among the older novi-belgii cultivars. The frikartii hybrids and the aster relatives are markedly more resistant.

Frequently asked questions

How do I grow Aster lateriflorus 'Horizontalis'?

Plant in an open, airy position — crowding is what brings on mildew. Divide every second or third year to maintain vigour, and pinch or Chelsea-chop the taller kinds in late spring to reduce the need for staking.

Where is the best place to plant Aster lateriflorus 'Horizontalis'?

Aster lateriflorus 'Horizontalis' prefers full sun. It suits exposed or sheltered positions.

What soil does Aster lateriflorus 'Horizontalis' need?

Aster lateriflorus 'Horizontalis' grows best in fertile loam; avoid thin and dry soils soil. It prefers neutral to slightly alkaline soil. Aim for soil that stays moist but well drained.