The genus Aster is a huge group of plants. Many, including this one, are tough clump-forming herbaceous perennials from the North American prairies, which do well in Sydney gardens. Aster cordifolius 'Silver Spray' (ht 1.2m) generally begins to flower in late summer and continues into early autumn. However, in some years it flowers much earlier in summer in my garden - if cut back after these fade, it may rebloom in late summer or early autumn. It has clouds of dainty pale mauve-pink daisy flowers, which form a pretty haze in a flower border.
These plants do best in full sun in reasonable soil with good drainage, and they will stand periods of dryness and heat quite well. The stems can be cut to the ground in winter. They can be propagated from dividing the clumps every few years. Unlike some Aster types, it doesn't seem to suffer from powdery mildew.
The flowers mingle well with ornamental grasses to recreate a 'prairie' effect but also combine with other summer flowers such as Dahlia and Salvia , the petite blooms providing a contrast of form against these bolder shaped flowers.
Note that the correct botanical name of this plant is now Symphyotrichum cordifolium.