Perennials: Aster
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Up to 1.2m (4ft) |
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25cm-60cm (10-24in) |
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September to first frost |
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Fertile well-drained soil |
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Full sun |
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Powdery mildew & Ater wilt |
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Cut back after bloom |
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Medium |
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Low - medium |
Asters
Common Name: Aster
Family: Asteraceae
Native Range: None
Bloom Color: Pinks to blues with yellow centers
Asters are an extremely popular garden perennial favored for it's late blooming season when most other, early flowering perennials are well past their best. The blooms of the Aster are a small, daisy-like flowers which have a yellow center and grow in clusters. The flowers, which measure from 8mm (1/3 in) to 5cm (2in) across, range in color from white to varied blues, pinks, reds, purples and lilac.
Border Asters have leaves which are mid to dark green or gray-green. They grow in a strong upright habit, the stems branch heavily towards the very top creating a compact cluster of leaves and flowers. Unfortunately the flowers are often not very long lasting and can quickly go to seed.
The most popular species of all the Asters is A. novi-belgii or Michaelmas Daisy which is so easy to grow that it needs to be lifted, divided and replanted every two years, and in some areas annually. The Michaelmas Daisy, like all Asters, make excellent cut flowers and are a popular addition to many flower arrangements.
More about Asters below, after this video presentation
Cultivation
Asters grow best in fertile well-drained soil in an area which is sunny or will receive most direct sunlight. New plants should be planted from mid fall to early spring. During the flowering period Asters demand much water and the ground must not be allowed to dry out. The larger, taller, varieties of aster may require external support, especially in exposed areas.
Propagation
Asters are very easy to propagate. The best way to propagate Asters is by division of the roots which can be done at any time from mid fall to early spring. Simply split the clump of roots and replant, if a large number of new plants is required just separate the root ball into single shoots in early spring and replant. Some species, such as A. novi-belgii, require this to be done annually as the plant may become invasive (see pests and diseases below).
Pest and Diseases
Asters usually grow well if cultivated correctly but they are sometimes susceptible to powdery mildew. Powdery mildew is fungal and appears on leaves as a white, or very light gray, powder. Though it hardly ever kills a plant it does look rather unsightly. Prune out any infected material and burn it. If this fails several fungicides are available.
Aster novi-belgii can often suffer from Aster wilt which causes the stems of the plant to brown and wither. Aster wilt seriously damages growth and causes shoots to wilt and die. Many other species and varieties of Asters can be affected by Aster wilt but it is generally accepted that A. novae-angliae is immune. Verticillium Wilt is a fungal disease but fungicides are usually not very effective.
As mentioned above Asters can grow from even the smallest section of root. This makes removing Asters rather difficult and time consuming. In some areas. The problem is compounded by the fact that Asters self seed easily and in some areas they can become invasive. At the Barnwell Nature Reserve in Cambridge in the United Kingdom there is an ongoing battle against Asters as the Michaelmas Daisy is threatening to overpower the native Chalk grassland species they are trying to protect. A. novi-belgii is a common sight across Great Britain.
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