Blue Danube is one of the best-known cultivars of Stokes' aster, selected for the pale lavender to soft blue flowers that gave it its riverine name. It grows 12 to 18 inches tall and wide, a compact and tidy presence in the front of a mixed border, and it attracts a dependable crowd of bees, butterflies, and hummingbirds through its summer bloom period. The fluffy, cornflower-like heads are distinct and showy despite the plant's modest scale.

Once established, Blue Danube handles drought and heat with minimal fuss, and it holds its own against deer and rabbits without any intervention. Deadheading spent flowers encourages new buds and extends the blooming window. After the season ends, cutting back to the basal foliage keeps the plant tidy; in warmer climates the rosette often persists through winter as a green presence in the garden. Division every three to four years maintains vigor. Plant in sun to partial shade in moist, well-drained soil, and consider it for containers, walkway edges, mass plantings, or anywhere a reliable and easygoing summer perennial is needed.