Symphyotrichum sericeum aka Silky Aster

Symphyotrichum sericeum is a perennial in the aster family. Common names include silky aster and western silver aster. The RHS also calls it silky starwort. Its older name is Aster sericeus. It grows wild in central and eastern Canada and the United States. Its range reaches from Ontario and Manitoba south to Texas and New Mexico. In the central plains, it grows in dry, open sites. These include woods, bluffs, prairies, and glades. It is not native to Britain or Ireland.

Garden plants reach about 1–2 feet [0.30–0.61 metres] tall. Their spread can reach 2 feet [0.61 metres]. Chicago Botanic Garden describes a height of 1 foot [0.30 metres]. The plant has an upright form with thin, wiry stems. Small leaves grow along these stems. Each leaf has a pointed tip and an oblong to elliptic shape. Leaves reach about 0.1 feet [0.03 metres] long. This modest size suits planting near the front of borders.

The daisy-like flowerheads have lavender to purple rays around yellow centres. Each head carries 10–22 rays. Flowerheads can span about 0.125 feet [0.038 metres]. Missouri Botanical Garden places the main display in late summer and early autumn. Chicago lists a broader flowering window, from July through October. Its plant summary highlights September and October. The flowers attract butterflies and bring late colour to garden beds. Both the flowers and foliage have garden value.

Grow silky aster in full sun or partial shade. It needs acidic soil that drains well. Dry to moderately moist soil suits it. It tolerates drought, dry ground, and shallow, rocky soil. Chicago lists it for USDA zones 4–5. Missouri Botanical Garden describes it as easy to grow with little upkeep. Plants grow from seed and may seed themselves into nearby ground. Use it in native plant beds, cottage gardens, or rock gardens. It also suits butterfly gardens and dry, open areas. It can form part of a naturalised planting.

Serious pest and disease problems are not usual. Powdery mildew can occur, and aster wilt is another possible problem. Wilt poses more risk in clay soil that drains poorly. Good drainage therefore matters when choosing a planting site. Chicago Botanic Garden also lists resistance to deer.