Aster umbellatus (tall flat-topped white aster) — Clump-forming, upright to bushy

Overview

Aster umbellatus 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 umbellatus 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, wildflower gardens and naturalized areas. It is native to Canada and United States.

About

Aster umbellatus is a clump-forming perennial in the Asteraceae, notable for its tall, flat-topped clusters of white flowers from August to October. It carries upright to well-branched stems with deciduous, simple leaves that are often narrow and roughly textured. Position it in full sun on a south-, east- or west-facing site in fertile loam that remains moist but drains freely.

Wikipedia contributors, CC BY-SA 4.0 — Doellingeria umbellata

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 umbellatus originates from Canada and the United States and forms a clump of upright, well-branched stems bearing flat-topped sprays of white flowers in late summer and autumn (August to October). Leaves are deciduous, simple and often narrow with a rough texture, which places the floral display above a distinctive, textural foliage mass. Plant it in full sun on a south-, east- or west-facing position and use a fertile loam; avoid thin, dry soils. The soil should be neutral to slightly alkaline and kept moist but well drained. It will tolerate exposed or sheltered sites and is rated very hardy to fully hardy in UK terms (H6–H7), corresponding broadly with USDA zones 4–8. Tall Flat-Topped White Aster suits mixed borders, wildflower gardens and naturalised areas where a late-season white flowering has value. Give it room to form a clump and it will provide a clear, flat-topped white presence through August to October, sitting distinctly above its narrow, roughly textured leaves.

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 umbellatus size, habit and characteristics

Plant type: Perennial
Habit: Clump-forming, upright to bushy
Foliage: Deciduous; simple, often narrow and roughly textured
Suggested uses: Borders, wildflower gardens, naturalized areas
Native to: Canada, United States

Care notes

Pruning and caring for Aster umbellatus

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 umbellatus?

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 umbellatus?

Aster umbellatus prefers full sun. It suits exposed or sheltered positions.

What soil does Aster umbellatus need?

Aster umbellatus 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.