Just as many summer blooms are fading, asters take their opportunity to shine and brighten up the gardens. With many diverse and pollinator-friendly varieties, asters are an ecologically important member of the Asteraceae family and can be recognized by their daisy-like flowers. Plants in the Aster genus are referred to as “true asters” and are almost exclusively native to Europe and Asia. Taxonomic and molecular revisions of asters native to North America have been reclassified as belonging to two different genera, Symphyotrichum and Eurybia. However, the common name, aster, still informally persists. Throughout the Arboretum, you can find over 4,000 aster specimens, representative of all three genera, comprising over 18 different species and cultivars. We’ll mention a few notable highlights of the collection below!
Bushy and compact, the heath asters (Symphyotrichum ericoides), found in the Pollinator and Bird Garden, can grow to be 1 to 3 feet tall. Racemes (one-sided, dense sprays) feature white, daisy-like flowers with yellow centers. Heath asters attract butterflies and typically bloom in late summer to early fall. The heath aster cultivar ‘Snow Flurry’ featured in the gardens differs from the typical heath aster because they are shorter; they grow 4 to 6 inches tall and spread along the ground to form a dense foliage mat that can be seen sweeping over structures. Their flowers are also white, but typically bloom later in the fall from September to October.
Blue wood asters (Symphyotrichum cordifolium), stout plants that grow on smooth upright-arching stems, are located in the Pollinator and Bird Garden. These stems generally reach 2 to 5 feet tall. Pale- to rich-blue daisy-like asters densely adorn panicles atop the stems. The flowers attract butterflies and bloom in late summer heading into early fall.
Another butterfly-attracting aster, New England aster (Symphyotrichum novae–angliae), blooms from August to September(ish) and can be found at the Overlook Pavilion. Daisy-like flowers are generally deep pink-purple and are surrounded by rough, hairy leaves. ‘Purple Dome’ is another variety of New England aster that brightens up our Pollinator and Bird Garden. They also can grow 2 feet high, but their shorter petals are a deep royal purple with a rounded form.
Two attractive purple varieties of aromatic aster (Symphyotrichum oblongifolium) sweeten the Pollinator and Bird Garden. ‘October Skies’ features a compact plant with small, deep-blue flowers. When crushed, their blue-green leaves produce fragrance. ‘Raydon’s Favorite’ show off cheerful violet-blue flowers and also have blue-green leaves that are fragrant when crushed. These two often blend seamlessly when growing alongside one another.
Bees aren’t the only fuzzy ones in the Pollinator and Bird Garden! Frost or hairy aster’s (Symphyotrichum pilosum) stems and leaves are extremely hairy. Flowers rise in branching clusters and bloom from August to October. They emerge white and turn reddish-purple with age.
The Eurybia genus finally enters the garden chat. White wood aster (Eurybia divaricata) is a Pennsylvania native that can be seen growing in our Pollinator and Bird Garden, Childhood’s Gate Children’s Garden, and Hartley Wood natural areas. They are a sprawling plant that grows up to 2 feet tall. Tiny but abundant white flowers are arranged in flat-topped clusters. They bloom from August to October and can be distinguished by their unique heart-shaped leaves.
Asters provide a welcome pop of color into October and can even persist after the first few frosts. Plant them alongside your festive chrysanthemum displays to give pollinators (both insect and avian) a welcome boost! Asters are often considered a keystone species, filling the floral resource gap at a crucial time in the season. You can read more about the ecological niche these blooming beauties fill on the Penn State Extension site. You can also explore our aster collections further and find their locations in the gardens by searching our Arboretum Explorer Tool. Happy fall!
