This unusual shrub is sometimes known as the 'evergreen Hydrangea', and it belongs to the same broad family as the more familiar Hydrangea. It is a native of the foothills of the Himalayas from Nepal to China and Vietnam. It grows to around 2-3 m tall, with large evergreen toothed leaves. The flowers are star-shaped with prominent blue stamens and are massed in large rounded clusters. It is said that the flower colour will reflect the pH of the soil, so more acid soil will produce richer blue blooms and more alkaline soil will lead to pink-tinged ones. Bright metallic-blue berries can occur after flowering. It is regarded as a medicinal plant in China.
I have only recently acquired my specimen: it has grown incredibly quickly and lustily, and began flowering in winter. Dichroa is in bloom for a longer time than Hydrangea, with flushes from October to April. Deadheading of spent flowers will encourage this. It will grow in sun or part shade: apparently the colour of the flowers is more intense in shade, but the shape of the plant may become more open. It is also said to tolerate boggy or dry soil! If grown under tree shelter, it will tolerate mild frosts. I have found it strikes very readily from cuttings and seems ideally suited to the Sydney climate.
A good cultivar of Dichroa febrifuga is said to be 'Blue Cap'. There is also another similar species, known as Dichroa versicolor. I have heard that one species is supposed to be better than another, but I am not sure which, or in fact which one I actually have!
Dichroa looks good grown with true Hydrangea shrubs, to add interest; its tiny flowers echo the central fertile florets of the beautiful lacecap Hydrangea cultivars, as shown in the photo above.