When American plant hunter Dan Hinkley was searching near Wolong in Sichuan Province, China, he came across what he thought was a new species of buddleia. Not unlike. B. lindleyana, it carried grey-green leaves on stems up to ten feet tall. Only later was it identified as rostrinucula dependens, a member of the mint family. The genus consists of just two shrubs. both native to China.
Rostrinucula dependens likes a sunny position (although it will tolerate part shade) and a well-drained soil. Even after a hot summer, it will be September before the flowers start to form; in less favourable years, it will wait until October. These are carried at the end of the current year’s growth and are pink or purple, drooping downwards for several inches.
The shrub can be pruned in spring to keep it smaller – mine is about four feet now after seven years. But any cutting back should not be done until spring is well advanced as the new growth appears to be very sensitive to cold nights. Old growth will take -15C during the winter months, so this shrub should be suitable for all but the coldest areas on the UK.