Aster ageratoides aka Rough Surface Aster

Aster ageratoides has the common name balsam aster. It belongs to the Asteraceae family. Its native range starts in Sikkim. It runs through temperate eastern Asia and into Indo-China. This perennial lives for years in temperate regions. It is not native to Britain or Ireland. Gardeners grow it for its late flowers and bushy shape. It sheds its leaves for winter, then forms a leafy clump again.

Plants form round clumps with strong stems. Most reach about 2.5–3 feet [0.75–0.9 metres] tall. The RHS gives an upper garden height of 3.3 feet [1 metre]. Clumps can also spread to 3.3 feet [1 metre] wide. Plants take two to five years to reach full size. Their dark green leaves have toothed edges. Each leaf has a lance-like shape. The leafy mound forms a base for groups of flowers.

Dark violet buds open into blooms with yellow centres. The petals turn lavender as the flowers open fully. Chicago Botanic Garden lists blue and purple flowers too. Blooms span autumn and can last into early winter. Chicago lists September through December as the bloom season. Its account puts the focus on October and November. These late blooms offer a resource for pollinators. These are creatures that move pollen from flower to flower. The garden also notes visits from birds and butterflies. The long bloom season adds colour after many other plants finish.

Grow balsam aster in full sun or light shade. It suits soil with medium levels of nutrients. The soil must also drain well. The RHS lists clay, chalk, loam and sand as suitable. It also accepts acid, neutral and alkaline soil. Keep the soil moist, but let excess water drain. Chicago gives its water needs as moderate. The RHS rates its hardiness H5. Chicago gives USDA zones 4–7. Each rating describes how much cold it can stand. Each source bases this on its own growing conditions.

Use it in beds, borders or as a single feature plant. It can also serve as groundcover or provide cut flowers. The RHS lists pots and meadow planting as uses. It also lists planting beneath roses or shrubs. Remove faded flowers to keep the clump neat. Cut stems close to soil level in late autumn. Divide clumps in spring, or root softwood basal cuttings then. These cuttings come from soft shoots at the plant's base. Slugs, snails and leaf or bud eelworms may cause trouble. The RHS also lists wilt, powdery mildew and grey mould as possible diseases. These sources give no evidence on edible parts or toxicity.