Asters provide some of the best plants for the garden at any time of the year. They add a bright range of colors and shades, giving the border a much needed end-of-season lift. This large genus includes the well-known Michaelmas daisies, essential plants for the fall garden, many of which flower from late summer until the first frosts. Most also last well as cut flowers. The species are as worthy of consideration as the hybrids, some of which have an annoying tendency towards mildew. The genus also includes annuals.
Asters will grow in any reasonably fertile soil, in sun or light shade. Some will do well in poor soil. The taller forms often benefit from staking, especially in sites where they are exposed to strong wind, which can easily spoil them.
Aster ericoides, which is native to North America, has given rise to several garden-worthy forms. They have wiry stems that are starred with flowers, all with yellow centers, in the fall. ‘Blue Star’ has pale blue flowers; ‘Golden Spray’ has white flowers; ‘Pink Cloud’ has light mauve-pink flowers.
Aster x frikartii. This group of vigorous hybrids includes some of the best of the Michaelmas daisies, all with a long flowering season. ‘Mönch’ is an outstanding selection, which has large, lavender-blue flowers carried freely on branching stems. It is an excellent companion to shrubby lavateras. ‘Wonder of Stafa’ usually needs staking and has pinkish-blue flowers.
Aster x frikartii
Aster laterifolius. The species has an unusual habit: the erect stems produce flowering sideshoots, almost at right angles, giving a tiered effect. The flowers are white to pale lilac. ‘Horizontalis’, which is rather more spreading, has pale lilac flowers. The coppery tinges acquired by its dainty leaves as the weather turns colder enhance the appeal of the plant.
Aster novi-belgii. Although generally applied to the whole genus, strictly the common name, Michaelmas daisy, belongs to this species alone, the parent of a bewildering number of garden forms. It is often found growing as a weed, brightening up railway cuttings and areas of rough land with its violet-blue flowers in early fall, which suggests a use in a wild garden or grass. The colors of the garden forms range from white, through all shades of pink, to pale and dark lavender-blue and some purples. They vary in height from dwarf forms, which are good at the edge of a border, to more substantial plants. One of the best of the taller varieties is ‘Climax’, which has pale lavender-blue flowers in early fall. Among the good dwarf forms are ‘Jenny’, which has purplish-red flowers, and ‘Lady in Blue’, which has lavender-blue flowers.