While many flowering perennials fade or go dormant after a long hot summer, one beauty reliably bursts forth in bloom each fall. Asters, with their daisy-like flowers, create an attractive autumn display from late summer until frost.
Although asters freeze to the ground around Thanksgiving, new growth begins soon after. They develop ground-hugging green foliage, which is often hidden beneath plant debris until early spring.
Their flower color ranges from white to shades of blue, pink and purple with mostly yellow centers. They make good container plants and also perform reliably in a wide range of soil types.
Although asters are quite durable, most bloom best when given some attention. They respond well to soils enriched with organic matter such as compost. In Texas landscapes, asters should generally be trimmed back by one-third to one-half in June.
The two asters most often grown in North Texas gardens are Frikart aster (Aster frikartii) and Aromatic aster (Aster oblongifolius), which is also known as Texas aster. New England aster (Aster novae-angliae) and New York aster (Aster novi-belgii), which is also known as Michaelmas daisy, are mostly grown in cool regions. Some larger plants labeled as Aromatic aster are actually cultivars of Aromatic aster and New England aster.
Frikart aster is a widely planted perennial because it adapts well to many garden environments. It grows to 2’ tall and wide. It has dark green foliage and produces abundant lavender to violet-blue 2”-3” flowers. Frikart aster will begin to bloom in mid-summer if temperatures are moderate and rainfall is adequate. It may also bloom sporadically during extremely mild winters. Continuous bloom is best assured when spent flowers are regularly removed.
Aromatic aster is a very reliable performer in North Texas gardens. It is one of the last flowers to bloom before freezing weather, producing small 1-inch, blue to violet flowers with yellow centers. The plant covers itself in compound, daisy-like blooms for several weeks from late summer through late fall, persisting in most instances through heavy frosts. The pale green leaves are aromatic when crushed, but the flowers have no noticeable scent.
Grow aromatic aster in an open, dry site where it receives full-to-part sun for most of the day. Poor, rocky soil with a high pH is well tolerated — almost preferred. In moist, highly fertile sites, asters struggle to compete against other plants. Aromatic aster will tolerate harsh conditions including drought, high heat, cold winters, poor or highly alkaline soil and strong winds.
Under cultivation, this native perennial grows 1’-3’ tall and wide and is hardy to USDA Zone 5. Asters are often grown in mixed borders, rock gardens and dedicated perennial beds, but they may be incorporated into any part of the landscape where growing conditions meet the plants’ cultural needs. They are excellent late bloomers, which adds texture and color to fall gardens.
Native bees and butterflies visit aster flowers.
Resource: Perennial Gardens for Texas, Southern Living Gardens, Sunset Western Gardens
For answers to horticulture questions, call 817-579-3280.