Smooth Aster

Smooth aster ‘Bluebird’ is an upright, clump-forming North American perennial with smooth gray-green foliage and violet-blue flowers centered in yellow. Its late-season bloom supports a sunny border, meadow or pollinator planting after many summer flowers have faded. ## Flowers and Landscape Use The flower heads appear in fall, with the Pennsylvania State University profile noting September in southern Pennsylvania. Denver Botanic Gardens records the cultivar as Symphyotrichum laeve ‘Bluebird’ and lists violet-blue ray flowers with yellow disk flowers. The plant was introduced by Dr. Richard Lighty of Mt. Cuba Center; it is a named cultivar of smooth aster, rather than a generic blue-flowered aster. ## Growing Conditions Give it full sun to partial sun and ordinary well-drained garden soil. The species tolerates varied conditions, but flowering and sturdy stems are usually best with adequate light and moisture. The Penn State profile places it in USDA zones 4–8 and describes flowering stems around 3–4 feet tall. The existing narrower width figure is retained because authoritative sources vary in their stated mature spread. ## Maintenance Allow space for the upright clump and good airflow. The Penn State profile says this cultivar generally needs neither pruning nor staking; staking may still be useful in exposed sites or unusually rich soil. Cut stems back after frost or in early spring. [Denver Botanic Gardens plant record](https://navigate.botanicgardens.org/weboi/oecgi2.exe/INET_ECM_DispPl?DETAIL=1&NAMENUM=53596&startpage=1) · [Penn State Extension ‘Bluebird’ profile](https://extension.psu.edu/smooth-aster-bluebird)