How to grow Aster (as-ter)
From the Greek aster, star, describing the flower shape (Compositae). Michaelmas daisy. Among the most useful herbaceous perennials, most of the asters flower in late summer right into the autumn and are extremely hardy and easy to grow. They increase so rapidly, in fact, that many of them have to be lifted and divided about every second year. There are a great many cultivars suitable for the back of the herbaceous border, growing to about 6 feet in height, derived from A. novi-belgii and A. novaeangliae but there are also shorter, bushier cultivars, up to 3 feet in height that have been raised from A. amellus and A. frikhartii. These dwarfer varieties are also earlier flowering than the taller kinds. The really dwarf cultivars, from 9-15 inches tall, are excellent plants for the front of a border, as they are compact and very free flowering.
There are asters, too, for the rock garden, such as A. subcaeruleus, which flowers in June; the bright violet-blue flowers are produced on 9 inch stems and stand up above the foliage which makes small clumps as it spreads.
The two groups, A. novi-belgii and A. novae-anglaie are very similar, but the foliage in the novi-belgii group is smooth, whereas that of novae-angliae is downy.
A great deal of hybridizing has been carried out with Michaelmas daisies, the largest variations are to be seen in the novi-belgii group where the colours range from white, pinks, mauves, to deep rose-pink and purple. There are double and single flowers, and some of the varieties are short and bushy, more like the amellus group. In the nova-angliae group the colours are confined to deep pinks and purples and the flowers have an unfortunate habit of closing at sundown.
Species cultivated A. acris, 3 feet, masses of lavender-blue flowers in midsummer. A. alpinus, 6 inches, purple flowers in midsummer; 'Beechwood' is a fine cultivar. A. amellus, 2 feet, purple flowers in midsummer. A. cordifolius, 2 feet, mauve flowers on arching stems in summer. A. ericoides, 2-3 feet, abundant white flowers in autumn, angular branching habit: 'Perfection', 4 feet, white and 'Ring-dove , 4 feet, rosy mauve, are two cultivars. A. farreri, 1i feet, flowers long rayed, violet-blue in summer. A. x frikartii, 3 feet, flowers lavender-blue, in midsummer; 'Wonder of Staff, lavender-blue, is a popular cultivar. A. linosyris, goldilocks, 1i feet, a native with showy golden-yellow flowers in late summer. A. novae-angliae, 5-6 feet, autumn-flowering, purple flowers. A. novi-belgii, 4 feet, blue flowers in autumn. A. pappei, 1 foot, bright blue flowers throughout summer and early autumn. Not reliably hardy except in milder places. A. subcaeruleus, 9 inches, violet-blue flowers on 9 inch stems above the foliage; 'Wendy , 1 feet, pale blue with orange centre, a fine cultivar. A. thomsonii, 15 inches, pale blue, a parent, with A. amellus, of the hybrid A. x frikartii. A. tradescantii, 4 feet, white flowers in autumn. A. yunnanensis, 1 foot, lilac-blue flowers in summer; 'Napsbury' has larger flowers of heliotrope-blue.
Cultivars Named varieties of the major groups are numerous and new ones seem to appear each year and it is worth visit ing a nursery or consulting an up-to-date catalogue before ordering plants. Among the best are the following:
Amellus 'Blue King', 2 feet, bright blue. `King George', 2i feet, bright blue; an old favourite. 'Sonia, 2 feet, clear pink. Novae-angliae `Barr's Pink', 4 feet, 'Harrington's Pink', 41 feet, clear pink, both old varieties. 'Lye End Beauty', 4 feet, pale plum and 'September Glow', 5 feet, ruby, are both newer varieties.
Novi-belgii 'Apple Blossom', 3 feet, cream, overlaid pink. 'Blue Radiance', 3 feet, large flowers, soft blue. 'Crimson Brocade', 3 feet, bright red, double. 'Little Pink Boy', 2 feet, deep pink. 'Marie Ballard', 3 feet, mid-blue, large fully double. 'My Smokey', 6 feet, deep mulberry, vigorous. 'Orlando', 3 feet, clear pink, sinngle. 'Peerless', 4 feet, soft heliotrope, semi-double. 'Sailing Light', 3 feet, deep rose. 'Sweet Seventeen', 4 feet, lavender-pink, fully double. 'The Cardinal', 5 feet, rose-red. 'The Rector', 3 feet, claret. 'White Lady', 5-6 feet, pure white. 'Winston Churchill', 2 feet, ruby-crimson.
Dwarf 'Audrey', 15 inches, large, pale blue. 'Lilac Time', 1 foot, soft lilac. 'Pink Lace', 15 inches, double pink. 'Professor A. Kippenburg', 15 inches, light blue, semi-double. 'Snow Cushion', 10 inches, white. 'Victor', 9 inches, light blue.
Cultivation Their cultivation is simple: plant in the autumn or spring except the amellus group which dislike autumn planting and so must be planted and divided in the spring. They like a sunny position but will tolerate a little shade, and though they will repay good cultivation they are not fussy about soil. They are readily increased by division. Attacks by powdery mildew often whiten the leaves and make them unsightly.