Easy-to-grow asters come in a variety of shapes and sizes to suit gardens of all dimensions, shapes, and styles—especially cutting gardens and sunny or lightly shaded borders. Although a few species bloom in early spring, most put on a spectacular flower display, supported by evergreen foliage, from late summer well into fall when other summer blooms may be fading.
Asters get their name from the Latin word for "star," and their flowers are often the superstars of the fall garden. Some types of this native plant can reach up to 6 feet with flowers in white and pink but also, and perhaps most strikingly, in rich purple, showy lavender, and occasionally blue.
Aster Care Must-Knows
With several hundred species available, an aster can be found for most growing conditions short of full shade. This plant prefers moist, well-drained soil; overly wet soil leads to rot. Some asters require nutrient-rich soil; others need lean soil lacking organic material. Most asters should be grown in full sun to prevent flopping, especially in shady or windy locations. Woodland species tolerate shade, but need morning sum to produce the prettiest flowers.
Aster can be grown from seed, but expect uneven germination. It may be easier to purchased plants at a garden center. Space the transplants 1 to 3 feet apart, depending on the species, add mulch to keep the soil cool and prevent weeds, and water generously. Pinch back the tips of young plants to encourage bushiness. If your region receives less than one inch of rain a week, continue to water aster on a regular basis. If your plants lose flowers, or are not flowering well, they are getting too much or too little moisture. Try a different watering method.
Remove spent flowers after aster has finished blooming for the season to prevent lanky unwanted seedlings that may not resemble the original plant. Divide fast-growing every few years in spring or autumn, which helps plants maintain vigor and keeps them from dying out in the center. Watch for powdery mildew and rust diseases on the leaves. Chrysanthemum lace bugs sometimes show up and suck nutrients from the leaves, but can be controlled with insecticidal soap.
More Varieties of Aster
'Alma Potschke' New England Aster
Symphyotrichum novae-angliae 'Alma Potschke' blooms from August to frost with red-violet daisies on a plant 4 feet tall. Zones 4-8.
Symphyotrichum lateriflorus is a 2- to 3-foot-tall mounded, shrubby plant with pinkish-white daisies in September and October. Zones 4-8.
'Fellowship' New York Aster
Symphyotrichum novi-belgii 'Fellowship' has clear pink daisy flowers on plants that reach 3 feet tall. Zones 4-8.
'Purple Dome' New England Aster
Symphyotrichum novae-angliae 'Purple Dome' grows only 18 inches tall and has bright purple flowers in September and October. Zones 4-8.
Symphyotrichum x frikartii 'Monch' forms a tidy mound 2 feet tall and wide with lavender-blue semidouble daisylike flowers from June to September. Zones 5-8.
Symphyotrichum x alpellus 'Triumph' is a petite summer bloomer, reaching only 1 foot tall. Its compact form is ideal for the front of the border or container gardens. Zones 4-9.
'Wonder of Staffa' Aster
Symphyotrichum x frikartii 'Wonder of Staffa' is similar to 'Monch', but grows 28 inches tall and has paler blue blooms. Zones 5-8.
Aster Companion Plants
Looking almost like a tall baby's breath, boltonia is a large, late summer showstopper in the perennial border. Also known as white boltonia and white doll's daisy, its 1-inch-diameter daisy-like blooms may be white or light pink. Cut it back in early summer to promote a sturdier branched plant that requires no staking.
With its tall wispy wands of lavender or blue flowers and silvery foliage, Russian sage is an important player in summer and fall gardens. It shows off well against most flowers and provides an elegant look to flower borders. The aromatic leaves are oblong, deeply cut along the edges. Foot-long panicles of flowers bloom for many weeks. Excellent drainage and full sun are ideal, although very light shade is tolerated. Plant close to avoid staking since the tall plants tend to flop.
Sedums are nearly the perfect plants. They look good from the moment they emerge from the soil in spring and continue to look fresh and fabulous all growing season long. Many are attractive even in winter when their foliage dies and is left standing. They're also drought-tolerant and need very little if any care. They're favorites of butterflies and useful bees. The tall types are outstanding for cutting and drying. Does it get better than that? Only in the fact that there are many different types of this wonderful plant, from tall types that will top 2 feet to low-growing groundcovers that form mats. All thrive in full sun with good drainage. Ground cover types do a good job of suppressing weeds, but seldom tolerate foot traffic. Some of the smaller ones are best grown in pots or treated as houseplants.