Wisteria brachybotrys White Silk

Wisteria brachybotrys 'White Silk' is derived from a highly floriferous species recognisable by its short but divinely scented clusters of pure white flowers. They bloom abundantly in spring, among the young leaves, even on young plants. This highly voluble and vigorous climbing plant is much less exuberant than its Chinese cousin, making it suitable for smaller gardens. It is hardy and thrives in most non-calcareous soils, in sunny locations.

Wisterias belong to the Fabaceae family, formerly known as Leguminosae, a group so vast that it has been divided into three subfamilies: Mimosoideae (acacia, commonly and mistakenly called mimosa, inga, calliandra), Caesalpinioideae (including the well-known cercis and gleditsia in temperate climates), and Fabaceae, recognisable by their papilionaceous flowers (colutea, caragana, genista, etc).

Wisteria brachybotrys (synonym W. venusta) is commonly known as silky wisteria, due to its young silky grey foliage. It is a climbing plant native to the Far East, but less vigorous than its Chinese cousin (W. sinensis) or Japanese wisteria (W. floribunda). This makes it ideal for small gardens or to adorn more compact pergolas without the risk of invasion.

'White Silk' generally reaches a height of 5 to 6m (16 to 20ft) and a width of 4 to 5m (13 to 16ft), but can grow beyond that if it is never pruned. Its voluble stems bear bright green leaves divided into 9 to 13 ovate leaflets, measuring 4 to 7cm (2 to 3in) in length. Its stems twist anti-clockwise around solid supports. The abundant flowering takes place in May-June, at the same time as the soft and touchable young foliage unfolds. It takes the form of pendant clusters, 15 to 20cm (6 to 8in) long. They are highly fragrant and attractive to bees. The clusters are shorter and more compact than those of Chinese wisteria, but are equally decorative with their beautiful pure white colour. The upper petal, called the "standard" due to its larger size, bears a discreet yellow spot in its centre. The flowers develop into toxic fruits in the form of flat pods that eventually open, expelling large dark seeds. The mature foliage turns yellow in autumn before falling.

This wisteria grows well in most acidic to neutral soils, and even slightly calcareous ones (in this case, dig a planting hole large enough to mix compost and topsoil with the existing soil). It is very hardy (down to -20°C (-4°F) or even lower). It blooms from a young age, especially when lateral shoots are pruned to 2 to 3 leaves to encourage floral clusters. Prune after flowering and later, if necessary, to limit its growth.

This wisteria is perfect for covering a wall, railing, pergola, arbour, or porch in a romantic garden, including smaller ones. While wisteria branches can often twist even the strongest support, this variety is much more "respectful". Few people know that it is possible to train Wisterias brachybotrys "as a tree". Simply plant a hollow galvanised steel tube in the ground, place 3 or 4 "petals" made of twisted reinforcing steel at its upper end, pushing them into the tube to hold them in place, thus forming a support that resembles a flower. Then plant 'White Silk' and the purple-flowered W. 'Okayama' at the base of this support. In the first year, weave the shoots of both plants around the support until they reach the reinforcing steel, then guide them to cover the support you have created. After 3 to 4 years, the metal structure will disappear under the stems and foliage, and passersby will stop in awe to contemplate the magnificent scene you have created!