Isodon (Plectranthus) longitubus 'Kutani'

Japanese Isodon Lamiaceae

A superb late-season Isodon and one of those plants that seems to have deliberately waited until everything else has run out of steam before making its entrance. ‘Kutani’ is a Japanese selection of Isodon longitubus, introduced into Western horticulture and formerly sold under Plectranthus and Rabdosia—a genus with a botanical history almost as complicated as its flowering season. 

From late summer into mid- to late autumn, upright, branching stems carry airy clouds of deep sapphire-blue to purplish-blue, long-tubed flowers. As flowering begins, the otherwise bright green foliage develops striking deep purple tones, giving the whole plant an unusually rich autumnal colouring. 

An excellent woodland perennial for part shade and reasonably moist, humus-rich soil, where it forms a full, bushy plant and provides valuable late nectar for insects. It is particularly good planted where its autumn display can be seen against darker foliage.

Height: 90–120cm | Spread: 60–90cm
Flowering: September–November | Foliage: Deciduous
Hardiness: H5 (-15 to -10°C)