Hibiscus flowers are some of the most exotic in the garden. These hardy shrubs are one of the last to break into leaf in late spring. But once they do, they're clothed in pretty three-lobed foliage until a late summer explosion of tropical, silky blooms that last right through into October, when much else had faded. Hibiscus 'Oiseau Blue', or 'Bluebird' as it is often named, requires little maintenance but enjoys a long, hot summer to produce the most stunning blue hibiscus flowers. Grows 8' x 4-6'.