Symphyotrichum patens aka Spreading Aster

Symphyotrichum patens is a perennial in the daisy family, Asteraceae. Common names include spreading aster and late purple aster. It also has the older name Aster patens. Its native range spans the central and eastern United States. It grows in rocky or sandy woods and thickets. In Missouri, it also grows along glade edges in the Ozarks.

Plants reach 2–3 feet [0.61–0.91 metres] tall in gardens. They spread about 1.5–2 feet [0.46–0.61 metres] wide. The form ranges from upright to arching or mounded. Slender stems bear short, curved hairs and break with ease. The simple leaves grow alternately along the stems. They are hairy, rough, and lance-shaped to oblong. Their bases clasp the stems without leaf stalks. Leaf edges may be smooth, slightly toothed, or wavy. Veins show on the undersides of the leaves.

Blue to violet flower rays surround yellow central disks. Each daisy-like head reaches about an inch across. Heads grow alone at stem tips or in end clusters. The fragrant blooms appear from August through October. Chicago Botanic Garden also lists flowering in July. Flowers supply nectar late in the growing season. Bees and butterflies visit them, and the plant attracts birds. The fruit is a small, ribbed achene. It has a few hairs and turns purplish brown.

Grow this aster in full sun for its preferred light. It also accepts part shade and some drought. Choose sandy or rocky soil that drains well. Soil moisture can range from dry to moderate. The plant tolerates salt, which suits coastal gardens. It grows in USDA hardiness zones 4–8. Its care needs are low, and its growth rate is moderate. Gardeners can propagate it by division.

Use it in native plant beds or along woodland edges. It also fits cottage gardens, borders, and pollinator plantings. Groups can provide a broad patch of late-season flowers. Rocky ground at a rock garden's edge suits it too. Sources report no major insect or disease problems. Powdery mildew and aster wilt can still occur. Poor drainage in clay can raise the risk of wilt. Good airflow and drainage help limit leaf disease.