Symphyotrichum lateriflorum

In the fall, numerous white-rayed flowers appear on the upper sides of calico aster's stems, suggesting branches lined with snow. The flowers supply pollen and nectar to wasps, hover flies, blow flies, honey bees, sweat bees, and bumble bees. In 2009, the Chicago Botanic Garden concluded a 7-year study aimed at identifying “outstanding asters for upper midwestern gardens.” Out of 119 asters and cultivars tested, the wild-type calico aster was one of just 7 plants that received the study’s highest rating of 5 stars. 

Inhabiting forests, forest edges, meadows, and wetland margins, calico aster displays broad adaptability in terms of sunlight and soil moisture. Growing best in consistently moist soils in partial sunlight, the plant also does well in full sun and can tolerate both moderately dry soils and periodic flooding. Although calico aster does spread via rhizome, it rarely forms large colonies and is not considered aggressive. Attaining a height of 2-3 feet, calico aster can form a fall-blooming border along paths and walkways. The plant also works well in shade gardens, where it adds fall color and pollinator value alongside plants like wreath goldenrod and zigzag goldenrod.

Calico aster and other asters have an especially fascinating way of communicating with pollinators. As the plant’s flowers become depleted of viable pollen, the flower centers turn from pale yellow to a rosy pink. The color change is the plant’s way of telling bees where to focus their pollen-gathering. This increases the plant’s reproductive efficiency, and the bees benefit from the greater nutritional value of the viable pollen. By keeping non-viable blooms open, the plant maximizes its visibility on the landscape, attracting more pollinators than it would if it shed its old blooms.

Photo 1 © Brian Gratwicke, CC BY 2.0. Photo 2 © Andrey Zharkikh, CC BY 2.0.