Aster Flowers for Perennial Fall ColorLearn how and where to plant 16 varieties of aster in your garden.
Western Aster, Symphyotrichum ascendens, growing in Grand Teton National Park in western Wyoming. Photo by: B Brown / Shutterstock.com.
Asters come in a wide variety and grow quite effortlessly. Colors are diverse, ranging from white and pastel blues and pinks, to hybrids of deep scarlet and purple. Asters have the iconic flower shape that signals we are looking at, essentially, a daisy. Their flowers provide a large store of nectar that attracts pollinators, they are disease and deer resistant, and bloom predictably and reliably.
GROWING AND CARING FOR ASTERS
Zones: 3–10; varies depending on species and cultivar.
Soil: All types of soil, but most prefer well-drained, organically rich soil. Learn more about preparing your soil here: Garden Soil 101.
Water: Once asters are established, they require little watering, unless conditions have become unusually dry and the plants show signs of stress. New York aster (Symphyotrichum novi-belgii) cultivars have shallow roots and may need more frequent watering during the summer, especially when planted in free-draining soils. Keep soil moist, but not saturated. Mulching to reduce water loss is an important strategy for preventing disease.
Exposure: Full sun, tolerates light shade, likes cooler summer temperatures.
Pruning: Pinching back stems, or deadheading, several times before mid-July helps to control plant height, promote bushiness, and encourages blooming through the entire season. Leave a few wilted blooms at the end of the season if you want your asters to self-sow. Learn more about pinching and deadheading here: Pruning Garden Shrubs and Perennials.
Staking: Taller stemmed varieties may require staking.
With such variety, it is easy to see why these autumn-blooming perennials take center stage in so many gardens. Here are a few varieties to explore:
Aster 'Little Carlow'
Compact clumps will reach 20 inches across in 2 years, producing sprays up to 4 feet tall. Free-blooming flowers are about 1 inch across. These are popular in formal borders and meadows. “Contrast the dense sprays of this aster with textures from other plants,” suggest Helen and Paul Picton, co-authors of The Plant Lover’s Guide to Asters.
Aster ×frikartii ‘Mönch’
One of the first hybrids by Swiss breeder Carl Ludwig Frikart (1918), this was named for one of three mountain peaks visible from his nursery. Lavender-blue flowers from late June through early October. The Pictons recommend pairing with Symphyotrichum novi-belgii ‘Saint Egwyn’.
Symphyotrichum novi-belgii ‘Jenny’
Compact, bushy sprays and intense color mark this dwarf New York aster. Purple-red double flowers are 2 inches across with sprays up to 15 inches tall.
Symphyotrichum novi-belgii ‘Carnival’
Magenta flowers with yellow discs grow from late summer into autumn. Try it in gravel beds, borders, and informal gardens.
Symphyotrichum oblongifolium ‘October Skies’
Aromatic asters are heat- and cold-hardy—and derive their name from the light scent they produce when crushed. These make good companions for small shrubs and trees; particularly chrysanthemum. ‘October Skies’ has purple-blue flowers .75 inches across and reaches 18 inches high.
Symphyotrichum laeve ‘Calliope’
Also known as smooth blue aster, ‘Calliope’ is unique for its height and purple-tinted stems, making it a good choice for cutting. It grows to more than 6.5 feet high in good conditions. As such, say the Pictons, “it lends itself to more wild or naturalistic planting schemes.”
Symphyotrichum novae-angliae ‘Helen Picton’
This New England aster sports vibrant purple flowers, 1.5 inches wide, in large sprays atop upright stems to 48 inches tall. According to its namesake, “Swaths of perennial grasses . . . can be given an easy boost of color in mid-autumn with large clumps of this aster.”
Symphyotrichum ericoides ‘Lovely’
This bushy heath aster bears masses of small, soft pink flowers from late summer through mid-autumn. Tall stems and deep green foliage make ‘Lovely’ excellent for cutting. More drought tolerant than many asters, it also does well in full sun in a border or container.
Symphyotrichum novae-angliae ‘Herbstschnee’
The pale coloring—white flowers 1.75 inches across with pale green foliage—makes this unique among New England asters. Woody clumps produce sprays of compact branches up to 4 feet tall, so it’s best suited toward the back of a border.
Symphyotrichum novae-angliae ‘Mrs. S.T. Wright’
Profusions of lilac flowers, 2 inches across, bloom on sprays that grow up to 5 feet tall. This classic cultivar introduced by H.J. Jones in the UK more than 100 years ago is still popular among gardeners and butterflies alike.
Symphyotrichum novi-belgii ‘Patricia Ballard’
The reliably blooming bright purple-pink double flowers, 1.75 inches across, on branched sprays that grow up to 36 inches tall make ‘Patricia Ballard’ a good choice for the front or mid-border. Bred at Old Court Nurseries by Percy Picton in 1957.
Symphyotrichum novae-angliae ‘Purple Dome’
One of the shorter New England asters, ‘Purple Dome’ produces branching sprays up to 24 inches tall. “This is a beautiful selection—naturally compact, floriferous, deep purple,” Jim Sutton says. “A dense grower with excellent mildew resistance.”
Aster amellus ‘Veilchenkönigin’ (‘Violet Queen’)
Each branchy clump of this compact plant grows to about 16 inches high and 12 inches across. The small violet flowers (2 inches across) seem to glow with depth of color. The Pictons recommend placing these blooms next to structural grasses.
Symphyotrichum novi-belgii ‘Coombe Violet’
Reaching to 4 feet tall with a 2.5 foot spread, this aster may need staking to hold up the masses of violet-purple flowers with sunny yellow centers. Semi-double flowers are attractive to pollinators and look wonderful paired with grasses, as it is here with Calamagrostis ‘Karl Foerster’.
Symphyotrichum lateriflorum ‘Prince’
A bushy plant with petite, skyward-facing white flowers a half inch across, this mid-fall bloomer differs from other varieties in the deep coloring of its spring growth. The yellow discs of the flowers fade to purple. Spreads to about 12 inches across.
Symphyotrichum ericoides f. prostratum ‘Snow Flurry’
Heath asters tend to have a bushy habit, hairy stems, smaller leaves, and sparser ray florets than other asters. This aster sits just 4 to 6 inches above the ground and spreads to about 1 foot. White flowers about a half inch across create what looks like a blanket of mid-autumn snow. The Pictons recommend planting ‘Snow Flurry’ where it can cascade.
EXPERT DESIGN TIPS
Choose Contrasting Companions
Hardy ornamental grasses and substantial foliage plants such as Yucca, Carex, and coleus provide a sturdy backdrop for softer or brightly colored asters. For Jim Sutton of Longwood Gardens, his favorite sustainable companion plant is kale—especially ‘Lacinato’.
Paul Picton, co-author of The Plant Lover’s Guide to Asters, says, “When planted en masse, billowing clouds of color will enhance and revive gardens at a time of year when most other flowers are fading.”
Planting asters alongside late-blooming perennials and grasses with strong color brings the autumn garden to life. Here, Aster ×frikartii ‘Mönch’ is joined by Rudbeckia fulgida ‘Viette’s Little Suzy’, Rudbeckia subtomentosa, Hydrangea ‘Annabelle’, Verbena bonariensis, Sedum ‘Matrona’, and Rosa ‘Rosemary Rose’, sweeps of Japanese forest grass, and black mondo grass. Photo by: Richard Bloom.
Put Them in a Container
Use a single bushy plant, or create a mini landscape with smaller asters and grasses. Picton suggests Aster cultivars, Symphyotrichum ericoides ‘Golden Spray’, and S. novi-belgii ‘Lady in Blue’ or ‘Rosebud’.
Pump Up the Color
Place asters next to other fall-flowering perennials, bulbs, and shrubs—or more asters. Mr. Picton recommends yellow and says goldenrods make wonderful companions for asters.
Plant a mix of tall upright stems, low spreading shrubs, and everything in between. Used as a mid-border plant, medium-to-tall asters will pop out after the summer blooms have gone off. “Come September, they get a chance to shine,” Sutton says.
“Asters from Symphyotrichum novi-belgii, S. novae-angliae, S. ericoides, and S. cordifolium are happy in an open, sunny site in soil that doesn’t get too dry in summer,” Mr. Picton says. “Other species such as Eurybia schreberi will be happy to grow in dry shade. Warmer conditions might be tolerated by some of the true Aster found wild in Europe and Asia.”
Whether you want a pop of late-season color or an addition to your pollinator garden, Asters could be the answer.
Portions of this article were adapted from a piece originally written by Meg Ryan for our print magazine.