The Sunken Garden and The South Border
A hardy perennial native to southern Brazil, Uruguay, and Argentina growing up to 6 feet (1.8 m) tall in one season, with multiple thin stems and yellow-green lance-shaped leaves that have serrated edges. The plant quickly spreads on underground runners and is readily divided. The bright azure-blue flowers are .5 inches (1.3 cm) long with a white beeline in the throat pointing toward the nectar and pollen. They grow in whorls beginning in summer until autumn, with many flowers coming into bloom at the same time.
Site and Care:
Humus rich, fertile, light, well-drained soil of any type in full sun or partial shade. Deadhead to encourage more flowers. It is hardy in the south of the UK but it is as well to protect it with a thick mulch over winter. Propagation is by cuttings in late summer or division in spring.