Aster

Even though written over two millennia ago, Virgil's mellifluous description gives a perfect picture of the aster. With a real feeling for nature, the Latin poet tells us the common name by which the flower was known to farmers; notes that it grows in fields; gives an accurate description of its growing habit; correctly states that the flower is yellow with purple petals that it has an acrid, sharp flavour; and that ailing bees are cured by the specially prepared roots.

Dioscorides called it Aster Atticus a name that persisted well into the Middle Ages. Nowadays, however, it is thought that this plant was indigenous to Italy, from where it was introduced into England many hundred years ago. Because of the flowers' starlike appearance, the name of genus Aster derives from the Greek word aster, and Linnaeus adopted it as the official generic name. At first, the genus contained many more species than it does at present, but many of them have now been transferred to other genera: Erigon, Calmymeris, and the popular annual China aster now placed into the genus Callistephus. Nonetheless, the genus is still quite large, and includes over two hundred annual and biennial species with an area of distribution that takes in South America and Asia, with a few found in Africa and Europe.

Cultivation. The general cultural requirements are the same for all species, although in a few cases a different soil texture is advisable; in such cases the exception is here referred to in the appropriate place. Ideally, asters require a deep reasonably light, fertile cool soil. Coolness is particularly indicated for the high-altitude species. lt is not necessary to be too scrupulous about cultural requirements since asters are easily satisfied and know how to adapt themselves. They are hardy, easy-going plants. They will thrive in gardens near the sea and even on sand dunes. They are not really suitable for complete shade, and although they give reasonably good results in sun, they are at their best in semi-shady positions. They are of particular value in gardens that cannot be given continuous daily care.

Propagation can be effected from seed, but as many of the perennial species are not prolific fertile seed producers, the best method of reproduction is by division. Seed can be sown from April to July in seed flats or boxes or in seed beds, the seedlings pricked out into nursery beds or open frames and then planted out in their permanent positions in autumn or in the following spring. Division can be accomplished in October or in early spring. More compact and freer-flowering specimens will result if the plants are topped when high and then again later.Perennial asters should be divided and replanted every two or three years, although under particularly favourable conditions this period can be prolonged until the plants begin to flower poorly and deteriorate in general. But to have really vigorous free-flowering plants, it is best to renew the plants frequently and because they are voracious feeders and rapidly exhaust the soil—to change the planting site every so often. One of the advantages of asters is that they can be easily transplanted, since their root system retains a good ball of soil, a feature useful to the plant collector who wishes to lift wild specimens. During hot dry summers, asters require constant watering, and the plants must never be allowed to suffer from drought if one desires really successful blooming.

Aster alpinus L.

Native to Europe, Asia, and North America. This is a species of such grace and charm that there is a risk of its becoming extinct in certain regions where it is easily accessible. An essentially alpine plant—and therefore of easy cultivation in the mountains it is difficult to establish in gardens that do not possess the cool, fresh, mountain air essential to its well-being. It thrives in the cold, and its worst enemies are drought and excessive heat; in gardens at low altitudes Aster alpinus should thus be planted in semi-shade in a cool, fresh soil. Large in proportion to the size of the plant, the flowers are solitary, borne on erect stems, violet- blue in colour, with a golden-yellow central disc. There are numerous hybrids with white, pink, or nearly red flowers. The flowering period is late spring, and when in bloom the plants are about high. Propagation is easy by means of division in spring, or from seed sown outdoors in pots or boxes, also in spring.

Aster amellus L.

Native to Southern Europe and Western Asia. When cultivating this species one should keep in mind that in its natural habitat it is invariably found in alkaline soils. A beautiful plant, and the parent of numerous, even more beautiful, hybrids. The flowers are very large, nearly  in diameter, with wide violet-blue petals that create an effective contrast to the yellow or nearly orange- coloured central disc. Each flower stem bears numerous blooms, and in the case of the hybrids the flowers are produced continuously from July to October according to the type. Although tolerant of full sun in the north, better results will be obtained if grown in partial shade in the south. The species can be propagated from seed as well as by cuttings and division. Hybrids, however, must be propagated by cuttings or division, as they will not breed true from seed. Division can be accomplished in spring or autumn, and soft cuttings should be taken in spring. The best time for seed-sowing is spring; in pots, flats, or boxes in coldframes or an unheated greenhouse.