Matthew Stevens: Asters serve as a compliment to goldenrod, mums

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 an herbaceous perennial (meaning 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. It 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.

Symphyotrichum laeve, or smooth aster, is slightly smaller at 2-4 feet high and wide, but otherwise fairly 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 1½ to 3 feet tall and 12-18 inches wide. It 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 than 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.

As native species, asters are an important part of our ecosystem and attract a number of different insect pollinators, and 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.