The Wisteria genus consists of ten species of woody climbing vines native to eastern United States, China, Korea, and Japan. Wisteria is reported to have been named by Thomas Nuttall after the physician and anatomist Dr. Caspar Wistar (1761-1818) although this has been disputed. Because of this Wisteria is often commonly spelt Wistaria or Wysteria. The worlds oldest Wisteria was planted in 1894 making it 123 years old in 2017. The flowers of some varieties have been used to make wine, however other varieties are known to be toxic so carful identification is important.
Culture for Wisteria
Wisteria vines can climb as high as 20m tall and spread around 10m. Wisteria is very hardy but prefers full sun, moist well drained soil. Ideal soil pH between 5.5 to 6.5. It is best to avoid overly dry soils. The plant flowers between April and June therefore pruning should take place in August and again in February and involve shortening new growth back to 2 to 3 buds. This will ensure flowers are visible.
Concerns about Wisteria
Powdery mildew, honey funugus, vine weevil, and scale insects affect Wisteria. Graft failure, often after many years of satisfactory growth, is a common problem with grafted Wisteria. Failure to flower has also been attributed to excessive nitrogen fertilisation owing to this plants ability to "fix" nitrogen from the soil.
Management Practices for Wisteria
Soil nutrient analysis is recommended when considering fertilising Wisteria plants. Do not over fertilise as this may prevent flowering. If necessary treat vine weevil, scale insects, and powdery mildew with a suitable insecticide or fungicide respectively. Graft failure is unfortunately irreversible.