Wisteria sinensis

Wisteria sinensis is surely the most distinctive of climbers and by far the most captivating when in bloom. Bearing large pendent clusters of fragrant violet-lavender flowers in late spring to early summer, they arise from bare stems; the foliage appears once the flowers are over.

Wisteria looks fabulous grown traditionally over a wall of a house or garden building or trained over a strong pergola. It can also be trained as a standard tree or allowed to scramble through a large tree where it looks most spectacular as well as being maintenance free.
This hardy climber withstands temperature down to -20°C and will give stunning displays every year. The plants bloom in spring, from April to May and bears fruit from May to August. The huge seeds are one or three in a bean, brown, shiny, about 1 to 1.5cm in diameter.
Germination from seed is very easy but like most wisterias, it is slow to get established and may take several years to start flowering, but once is does the rewards are immense.

Sowing: Sow in spring or autumn at 13 to 18°C (55 to 65°F)
Soak the seeds for 24 hours in warm water. Fill small pots or trays with good quality seedling compost, stand the pots in water and allow them to drain. Sow the seeds 2cm (0.78in) deep, cover with soil and spray the top with water.
Place the pots inside a plastic bag or cover with a plastic lid and place in a cold frame, greenhouse or even just a windowsill. Keep the soil misted, but not overly saturated.Germination occurs within 30 to 60 days (usually 3 to 4 weeks), Take the pot out of the bag and make sure it gets plenty of sunlight and not allowed to dry out.
After the seedlings have a set of true leaves, prick them gently out of the pot and pot up separately. Put the pots outdoors in a place that is protected from direct sunlight and extremes of weather, wind. They can be planted directly in the desired spot as long as you have at least 45 days before the first frost.

Cultivation:
Wisteria has a tendency to become dominated by foliage and stem if grown on a fertile soil rich in Nitrates and manure. For this reason, when planting don't improve the soil with anything other than organic matter, such as leaf mould, that would be found in its native moist but well drained forest habitat.
Wisteria grown from seed can take some years to mature and bloom. To aid flowering, apply a fertiliser high in phosphorus (the middle number in the NPK sequence on fertilizer bags) in early spring and prune carefully.

Training:
Aim for a single upright shoot that reaches the top of your climbing frame. Off this allow side shoots to develop, training them horizontally the edges of the frame. Secondary side shoots will occur off these and these should be allowed to last for one season before being pruned back to within 4 to 6 buds of the horizontal shoot. This should be done in late winter or early spring, before bud break.

Pruning:
Once the plant has reached the desired size, Wisteria may need to be pruned several times during the growing season especially if it is being grown as a tree form.
Probably the best or most common time is late in the winter just before the plant comes back to life. The main thing to remember is that the Asiatic species flower on the previous year’s wood, if all this was removed there would be no flowers. Generally it is good to cut back all the new growth to 3 or 4 buds each spring before bud break. The cultivars of W. sinensis tend to flower before the leaves emerge,

How to make a Tree form Wisteria:
The Wisteria should be pruned back to one shoot and this should be trained up a strong stake to about 6 feet. It should then have the growing tip removed. After a few weeks it will start to grow new shoots, all the new shoots below 4 feet should be removed and only the ones between 4 and 6 feet left to grow. When these shoots are 12 to 18 inches long they should be pruned back to 1 or 2 buds.
By continually repeating this process over a few years you will develop a Wisteria that will have a strong central leader and branches that are self supporting.

Ancient Specimens:
There are many ancient wisteria vines growing throughout the world, the photograph is of the widest wisteria at Ashikaga Flower Park in Tochigi, Japan. Aged approx. 140 years and branch spreads to size of 1,990 square metres as of May 2008. One of the oldest Wisteria grows in the Chinese gardens of Ushijima, it measures four metres around the trunk and is estimated at 1200 years old.
Sierra Madre, California holds an annual 'Wistaria Festival' every March during which visitors can view a vine that is 111 years old, weighs approximately 250 tons and bears over 1 million blossoms.
In ancient Japan it was a sacred plant, referred to as Fuji, hence the correct name for a Wisteria arbour being “Fuji Dana”. Wisterias are used in the art of bonsai and penjing (a Chinese method of producing miniature plants.)

Nomenclature:
The genus was named after Dr. Caspar Wistar (1761-1818), a professor of anatomy at the University of Pennsylvania. The name is sometimes given as Wistaria, but the spelling of Wisteria is conserved under the International Code of Botanical Nomenclature.
The species name sinensis means 'of or from China'. Sinensis derives from the Latin sinae, the Greek sinai and ultimately the Arabic san, the kingdom of China.