The original species came from the Indian Ocean area and was a tall evergreen shrub (ht to 4.5 m) with bright red flowers, known as the rose of China. Today there are thousands of cultivars available, including the huge-flowered Hawaiian hybrids (which tend to be lower growing than the others), which have been interbred with other species. They grow 1 to 3 m in height with single, semi-double or double flowers in hues of white, cream, pinks, lavender, red, orange, coral and yellow, flowering well from early summer into autumn. Each flower lasts only a day but there will be a profusion of them in an established shrub. The taller hybrids can form good background plantings or even hedges, especially in mild suburbs where they will not lose their leaves in winter. Compact specimens can be grown in wide pots, which will allow room for their surface roots to fan out across the surface. Water potted hibiscuses regularly and feed them with a slow-acting fertiliser.
The hibiscus's huge opulent trumpets with their cheeky protruding central column of fused stamens make it one of the most flagrantly tropical-looking of all shrubs that can grow in Sydney. So far I only grow one, which I think is the cultivar ' Apple Blossom' (single pale pink with a maroon centre), which I propagated from a tiny cutting stolen on a morning walk. The shrubs like a warm, sunny position in very well-drained, slightly acid soil. They appreciate ample water and benefit from an organic mulch to help retain moisture and keep weeds down; keep this mulch away from the trunk, however. They need frost protection in winter so don't do so well in areas with cold winters; move potted specimens into a sheltered position if possible. They can be pruned quite hard (by one-third to one-half) in early September (later in cooler areas) to keep them shapely; feed them in mid-spring then again in mid- to late summer for optimum blooming. A light prune in early January can extend the flowering season. They can be attacked by the hibiscus beetle, which makes holes in the large, glossy leaves. I try to ignore these! Aphids can also be a problem; use a horticultural oil to tackle these or squash by hand! Propagation is by semi-hardwood cuttings in late summer or autumn.