Asters are popular garden plants because of their showy flower heads and the availability of flowers in multiple colors.
Asters are beautiful perennials that are found wild in North America and southern Europe. The genus Aster includes some 600 species of widely distributed flowering plants in the family Asteraceae.
Asters are also called as Starworts, Michaelmas Daisies, or Frost Flowers. Asters are found chiefly in North America, with some species extending into South America; others are distributed throughout Europe and Asia. The word Aster is of Greek derivation and refers to the Starlike flowers that can be white, red, pink, purple, lavender and blue, mostly with yellow centers.
The genus Aster is now generally restricted to the old world species, with Aster amellus being the type species of the genus (and of the family Asteraceae). The new world species have now been reclassified in the genera Almutaster, Canadanthus, Doellingeria, Eucephalus, Eurybia, Ionactis, Oligoneuron, Oreostemma, Sericocarpus and Symphyotrichum, but still the new world species are also widely referred to as Asters in the horticultural trade.
Asters are actually 1 - 1.5 - inch flowers. Asters are very complicated flowers. An Aster flower is actually a collection of very tiny tubular flowers, grouped together in a central disk, and surrounded by so-called ray flowers or petals, eg., Sunflower. The central disk of flowers on the Asters is surrounded by the ring of ray flowers. In many cases the disk flowers are a different color than the petals so that the entire flower head looks like a single flower with a central disk surrounded by differently colored petals. The ray flowers on the Asters are never yellow. The tubular flowers of the Asters are bisexual, having both a pistil and stamens; the ray flowers are usually sterile.
Some popular varieties of Asters are: Lindley's Aster (Aster ciliolatus), New England Aster (Aster novae-angliae), Many-Flowered Aster (Aster ericoides), Western Silvery Aster (Aster sericeus), Willow Aster (Aster hesperius), Flat-Topped White Aster (Aster umbellatus), Smooth Aster (Aster laevis).
Facts About Asters
Aster plants are mostly coarse-growing, leafy-stemmed plants that are occasionally slightly woody at the base.
Most of the Asters are perennials, but a few are annuals and biennials.
All Asters have alternate, simple leaves that are untoothed or toothed but rarely lobed.
The leaves of the Aster plant are often dark green and, like the flower petals, can also be long, thin and pointed.
Asters generally bloom in late summer and fall, but Alpine asters (Aster alpinus) flower in May and June.
The two main groups of Asters are New England Asters (Aster novae anglias) and New York Asters (Aster nova belgii).
Asters are one of the easiest garden perennials to cultivate.
Asters' biggest problem is powdery mildew.
Asters are used as food plants by the larvae of a number of Lepidoptera species.
Asters are oftentimes a prime target for birds, bees and butterflies because they are fragrant and colorful.
Many species of Asters are drought resistant.
Asters depend on insects to pollinate them. Some insects that take pollen from one plant to another include bees, butterflies, and flies.
The seeds of Bushy Asters are small achenes, and look like parachutes, which usually spread by wind.
The China Aster (Callistephus cinensis), also a Compositae, a native of China, is related to the true Asters.
Asters may be propagated by dividing or grown from seed sown indoors at about 70 degrees F or may be sown directly into the garden after all danger of frost has passed. Germination takes anywhere from 15 to 30 days, depending on the temperature.
Asters should be planted in moist well-drained soil in full sun, but they will tolerate light shading.
Plant Asters at least 18 inches apart so that plants do not form broad bushy clumps.
Mature clumps should be divided every 3 - 4 years in the early spring, or late fall after the flowering has finished.
Pinch back the tops by 6-8 inches at least once during the summer, to create a bushier plant and to prolong the fall bloom.
Pinching must be done prior to mid July, or it will have an opposite effect, and blooming will be reduced.
Asters Plant Care
By planting Asters in a sunny spot with good air circulation, powdery mildew can usually be avoided.
Asters need regular watering at their roots.
Many Aster varieties fail to survive the winter if kept too moist.
Asters should be cut down after flowering to deter seeding. Even without seeding, Asters should be divided every three years to stay at their best.
Disease in Asters can be controlled by dividing them yearly in spring.
Pruning tends to delay flowering by only a few days but produces a much prettier plant.