Asters: A welcome sight in fall gardens

This week, let’s round out our discussions of fall-blooming perennials by considering the aster. Asters, botanically known as Symphyotrichum after a recent name change, are a genus of plants in the Asteraceae family (who would’ve guessed), also known as the daisy family. Their late arriving blooms are a welcome sight in fall gardens, and with flower colors mostly on the blue-purple edge of the color wheel they make a fabulous pairing with yellow and orange blooming fall plants such as goldenrod and assorted chrysanthemum varieties, which I mentioned in previous columns. Let’s look closer at a few of the most prominent species of Aster.

We’ll start with Symphyotrichum novi-belgii, known commonly as the New England or New York Aster, a species native to the east coast from Canada to Alabama. It is a herbaceous perennial (it dies to the ground in winter and returns in spring from its root system) with lavender purple petals that radiate from a yellow center, forming its disk-shaped daisy flower head. This aster is often found growing in salt marshes and other moist habitats in coastal areas. In garden settings it requires moist, but well-drained soil, and flowers best in full sun. It is a tall, upright grower, reaching 3 to 5 feet high and only 1-2 feet wide, and though the species is lavender in bloom, cultivars such as ‘Peter Harrison’ and ‘Royal Ruby’ offer pink or red blooms with otherwise similar attributes.

Photos: Top left: Symphyotrichum novi-belgii is commonly known as the New England or New York Aster. Photo: Uwe W., CC BY-SA 3.0 Bottom left: A field of New England Asters.

Top right: Symphyotrichum novi-belgii  'Peter Harrison' has pink blooms. Bottom right: Symphyotrichum novi-belgii  'Ruby Red' has deep red blooms.

Symphyotrichum laeve, or Smooth Aster, is slightly smaller at 2-4 feet high and wide, but otherwise fairy similar. Its native range extends a bit further west into the central part of the country, and is probably slightly more drought tolerant than the New England Aster. Both are quite tolerant of nutritionally poor soils.
 
Next is Symphyotrichum ericoides, or Downy Aster. This is a white-blooming species native to Canada, the central United States, and northern Mexico, typically found in fields, clearings, roadsides, and dry thickets. It’s a bit smaller than the other species mentioned so far, at a height of 18-36 inches tall and 12-18 inches wide. The Downy Aster tolerates shallow, rocky soils quite well, and is actually very useful in preventing soil erosion when grown or planted on slopes. This species has white flowers rather the blue and purple so many other asters are known for. The cultivar ‘Snow Flurry’ grows as a groundcover, creating a dense mat of white flowers 4-6 inches above ground.

Above left: Symphyotrichum laeve: The blooms of these Smooth Asters are from a second year plant. Photo: Tom Potterfield, CC BY-NC-SA 2.0 Above right:  Symphyotrichum ericoides: The Downy Aster has white flowers. Dan Mullen, CC BY-NC-ND 2.0

As native species, asters are an important part of our ecosystem and attract a number of different insect pollinators. They also provide food for birds and other animals. Pearl Crescent butterflies are known to frequent both the New England and smooth aster, as are a number of different native bee species. Songbirds and small mammals such as squirrels and chipmunks feed on the seedheads that persist after flowering, so consider leaving those throughout the winter before cutting the plants back in spring. Asters can be incorporated in the landscape in mixed perennial gardens, borders, pollinator gardens, native plant gardens, and rock gardens.
 
Matthew Stevens is the County Extension Director and Horticulture Agent for North Carolina Cooperative Extension’s Pitt County Center. If you have questions about this article or gardening in general, please contact the Pitt County Extension Master Gardeners at [email protected] or 252-902-1705.