As autumn unfolds, ornamental gardens may look a little bedraggled as summer blooms fade and go to seed. That’s when fall asters can provide a burst of color and interest! There is still time to plant these long-flowering and long-lived perennials.
Recommended asters
Two native aster species pack a particular punch: aromatic/oblong-leaved aster (Symphyotrichum oblongifolium) and blue wood/common blue aster (S. cordifolium). Both species have yellow disc-shaped flowers surrounded by rayed petals in shades of blue and purple, while their foliage and height differ.
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- S. oblongifolium has narrow leaves that get smaller as they climb the stem; both leaves and stems are covered with short hairs. Usually less than 20 inches tall, it has rigid stems and lots of branches, and is fragrant when crushed. Some of the more reliable, popular aromatic aster cultivars are:
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- ‘Fanny’,
- ‘October Skies’,
- ‘Raydon’s Favorite’.
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- S. cordifolium has sharply toothed leaves on smooth, upright arching stems 3 to 4 feet tall—the upper leaves are oval, while the lower are heart-shaped. Cut the stalks back in
Wood Asters mid-summer to form denser mounds. Deadhead to prevent unwanted seeding! Less commonly available in nurseries, there are some blue wood aster cultivars, but these are not necessarily more desirable than the species:
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- ‘Avondale’,
- ‘Photograph’
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- S. oblongifolium has narrow leaves that get smaller as they climb the stem; both leaves and stems are covered with short hairs. Usually less than 20 inches tall, it has rigid stems and lots of branches, and is fragrant when crushed. Some of the more reliable, popular aromatic aster cultivars are:
Although all these asters have some susceptibility to powdery mildew and aster wilt, they don’t have serious pest or disease problems, deer and rabbits ignore them, and they are drought- tolerant once established.
Featuring asters in your fall garden
Plant asters in formal flower beds—or in naturalized areas. Their soft colors blend well with other autumn flowers, such as goldenrods (Solidago spp.) and perennial fall sunflowers (Helianthus spp.) and are a noteworthy alternative to ubiquitous fall mums. They are an abundant late-season source of nectar and pollen for bees and butterflies, too!
Aromatic asters work especially well in mass plantings along walkways, where you can appreciate their balsam-like fragrance. Plant in full sun areas with well-drained soil and good air circulation. The showy small purple flowers have a long bloom season, lasting from late summer until the first frost. They spread by wind-dispersed seeds or underground stolons. To keep them from spreading too aggressively, deadhead often and divide in spring to disrupt root growth.
Blue wood aster prefers shade and moist, well-drained soils, thriving at woods edge or along stream banks. Deadhead to avoid unwanted spread.
Article by Buncombe County Extension Master GardenerSM Intern Anne Spruance
For more information:
Aromatic aster: https://plants.ces.ncsu.edu/plants/symphyotrichum-oblongifolium/
https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/mdpmcfs9053.pdf
Blue wood aster: https://plants.ces.ncsu.edu/plants/symphyotrichum-cordifolium/
https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=a78 8