Aster spp.: Aster

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Introduction

Aster is a genus containing around 186 species of plants native to both Europe and Asia (North American asters belong to the genus of Symphyotrichum and Eurybia). They are an upright, herbaceous perennial plant that may reach a height of 8 feet and spread of 4 feet, depending upon the species (Figure 1). Asters produce large flower clusters that may be white, purple, lavender, pink, and red in coloration (Figure 2). The Greek word Aster means star, describing the appearance of the flowers. Asters have 2- to 4-inch lanceolate leaves, which are deciduous (Figure 3). The plants tolerate drought conditions and poor soil; however, bloom quality will decrease in these conditions. This plant is well suited for mass plantings, use as edging in a landscape bed, to attract butterflies and other pollinators, or may be used as cut flowers in arrangements.

General Information

Scientific name: Aster spp.

Pronunciation: ASS-ter species

Common name(s): aster

Family: Asteraceae

Plant type: herbaceous, perennial

USDA hardiness zones: 3B through 8B (Figures 4 and 5); dependent upon species

Planting month for zone 7: year-round

Planting month for zone 8: year-round

Origin: native to Europe and Asia

Invasive potential: not known to be invasive

Uses: mass planting; edging; attracts butterflies and other pollinators; cut flowers

Availability: somewhat available, may have to go out of the region to find the plant

Description

Height: 1 to 8 feet; dependent upon species selection

Spread: 2 to 4 feet; dependent upon species selection

Plant habit: upright

Plant density: symmetrical habit with a regular (or smooth) outline and individuals having fairly identical forms

Growth rate: fast

Texture: fine

Culture

Light requirement: plant grows in full sun

Soil tolerances: acidic; slightly alkaline; sand; loam; clay

Drought tolerance: moderate

Soil salt tolerances: unknown

Plant spacing: 18 to 24 inches

Other

Roots: not applicable

Winter interest: no special winter interest

Pest resistance: long-term health usually not affected by pests

Use and Management

Aster is adaptable to a variety of soil conditions in a full-sun location. It is moderately drought tolerant; however, flowering will decrease in dry conditions. This plant may be used as a groundcover in mass plantings when spaced on 15-inch centers, or further apart for larger varieties. Aster is an excellent choice for pollinator gardens as it attracts butterflies, bees, birds, and other pollinators. It is also suitable for containers or above ground planters, or as a specimen. The showy flowers may be used as cut flowers in arrangements.

Aster spreads rapidly and may require frequent division. Thinning out dense growth of this plant will encourage blooming. Taller species of aster may require staking. Different species may have different care requirements and growth habits. Check with your local County Extension Agent for more information.

Aster is grown from seed, division, root cuttings, or stem cuttings. Division is done in October or early spring when flowering deteriorates. The seed germinates in 15 days indoors or 20 to 30 days outdoors.

Design Considerations

To showcase asters in your garden, focus on creating contrast with their fine, gray-silver foliage and vibrant flowers, which bloom in shades of white, purple, lavender, pink, or red. Their cool tones stand out beautifully against warmer tones, creating a stunning late-season spectacle. For texture, you have two main options. You can either pair asters with airy plants like muhly grass or other ornamental grasses to create a soft, harmonious meadow look, or you can contrast their delicate stems against bold, broad-leaved plants like coontie and iris to make their graceful form pop. Asters work well as specimen plants, in small drifts, or as mid-border plantings that provide a burst of color after summer blooms have faded. They are a versatile addition to any perennial garden, border, butterfly garden, or wildflower meadow.

Pests and Diseases

Pests issues include aphids (feed on lower leaf surfaces and flower stems) and Japanese beetles. Disease issues include leaf spot fungi (increased occurrence during rainy season), downy mildew (minor issue), powdery mildew (develops on lower parts as whitish coating on leaves), bacterial crown gall, and verticillium wilt.