Wisteria floribunda, the Japanese Wisteria is native to Japan. It typically reaches heights of 35', but can grow higher. It can be trained into a tree-like form and is also a common subject for bonsai, along with Wisteria sinensis.
Wisterias do not conform to normal bonsai styling; they are styled to show off their highly scented racemes. The flowering habit of Japense wisteria is perhaps the most spectacular of the Wisteria family. It sports the longest flower racemes of any wisteria; they can reach nearly half a meter in length. These racemes burst into great trails of clustered violet or blue flowers in early to mid-Spring. The flowers carry a distinctive fragrance similar to that of grapes.
The leaves are 10" to 15" long and contain 13 to 19 leaflets that are each 2-6 cm long. The leaf color is bright green, emerging leaves may be red-tinged. It also bears numerous poisonous, brown, velvety, bean-like seed pods that mature in Summer and persist until Winter.
Trunks develop picturesque fluted and muscle-like form, bark is gray in color. The stem is twining clockwise. Pruning encourages dense, compact foliage and flowering.
Hardiness zones 5-9, (-5°C/25°F, -26°C/-15°F) in Winter. Due to the high moisture content of the roots, it should be given some protection when temperatures drop below -5°C. It is not fussy about soil type or moisture, although its preference is a reasonably moist, well drained, rich to average mix. Full sun or partial shade.
Wisteria require large quantities of water in comparison to most other bonsai species and need heavy watering to keep them continually moist. In periods of hot weather during the Summer, they will happily tolerate their pots being stood in a shallow tray of water to keep up moisture levels. However, water trays, if used, should be allowed to dry out daily. Water heavily before and during flowering.
In general, Wisteria need more fertilizer than most bonsai. However, in order to ensure good flowering, feeding should be minimized during and immediately following flowering. Fertilize heavily in Spring before flowering and in late Summer and Autumn, until the leaves drop.