Purple-stem Aster

Symphyotrichum puniceum

Purple-stem aster is one of the most striking asters for wet conditions. The stems are a deep burgundy-red, almost crimson, and they hold that color all season -- a structural detail that reads as an ornamental feature even before the pale lavender flowers open in September and October. The flowers are numerous and loosely arranged, creating a cloud of soft color on stems that can reach six feet in moist, fertile conditions. It's one of the best asters for rain gardens, pond margins, and low, wet spots where drainage is imperfect. The deep root system makes it effective at absorbing and filtering stormwater. Monarchs and painted ladies use it heavily during fall migration, and the seed heads carry into winter as bird food. A tall, bold, ecologically valuable native for the wet site back border.