Wisteria
Wisteria sinensins // floribunda // frutescens
Magnificent flower abundance of a Wisteria
Second blossoming of Wisteria in midsummer
Wisteria kept in shape by summer pruning
The healthy foliage lasts well into autumn
Strongly structured and pruned Wisteria on a house wall in winter, guided along wire rope. Such a spartan stem support is necessary to prevent building damage.
The same Wisteria in the following midsummer, illustrating an exemplary summer cut.
Pruning: Already in summer, the (side) shoots are trimmed back regularly to approx. 30-40cm, to encourage flower producing woody stems. In winter (refer photo above), they are trimmed again down to about 3 buds. From these burgeons the flower buds will grow in the following spring. (Photo below).
Deformations such as on this photo (overstretched rope and bent wall bracket) can be avoided by training the stem parallel to the rope, as illustrated in the photo to the right.
The Wisterias are popular for their abundance of flowers and vigorous growth habit. Wisteria has been known for centuries in the Asian art of gardens. There are several hybrid forms which cannot be identified according to the direction of their twining etc, hence an exact species identification based on eg the twining (right or left) of available Wisterias is almost impossible. A poisonous plant. Inadequate espalier planning and maintenance can cause considerable Building damages.
Requirements
Position in full sun is best, areas with no direct sun but a high light density (eg courtyards) or semi-shade are possible, but plants will produce less flowers.
Growth and Leaves
An extremely strong and vigorous twiner, which can reach 20m height, a “Green Octopus” - the young strangling arms reaching an action radius of more than 1m. Light-shunning growth, into nooks and crannies etc, with blast-effect. Feathery leaves, mostly light green, sometimes with an orange-brown tinge. Foliage from May to November, rarely with yellow autumn colouring.
Flower and Fruit
Blue, white and pink species, in two main groups: Wisteria sinensis (Chinese Wisteria) and Wisteria floribunda (Japanese Wisteria). W. sinensis flowers at the beginning of May, mostly before the shoots appear, followed in midsummer by some sparse flowers. W. floribunda flowers a little later. Another kind, Wisteria frutescens (American Wisteria), develops flowers at an earlier age, but is frost tender. Opening flower buds deep blue and deep purple, fully open flowers soon fading to a grey-blue. Flowering time often simultaneous with that of lilac. Fruit are long and hairy pods. Non-grafted specimens often develop flowers after many years only, and in some cases bear but a few flowers.
Growth Support Systems
Solid, preferably rod-like support systems, designed for expected height and width of plant. A simple linear system rather than covering large areas, no timber trellises. Wire ropes are suitable if the main stem is guided strongly parallel to the wires, without twining, as illustrated in the photos. The short side branches are to be arranged so that any scratching of the wall render is prevented should windy conditions make the newel and hence the plant turn around. Lightning conductors, downpipes and eave gutters etc are not to be reached by the plant, all growth supports should have a distance of 2 metres from any such building elements and to the eave gutters, to the sides as well as from the top. For suitable rope systems see below, use Heavy Duty systems, in case of pot plants Light or Medium systems will be adequate.
Pruning
Summer and winter pruning as illustrated in photos. Regular pruning is absolutely essential to prevent damage to support systems.
Ancient Wisteria on a pergola in the Sankeien Garden in Yokohama / Japan. Photo: Regine Hartkopf
Overstretched and ingrown wire rope
Rope wire for breakfast: this Wisteria is still 'chewing away' on its ripped out support system...
Downpipe damaged by Wisteria, after unwinding the strangling stem to the left
Rope system, heavy duty assembly kit. Already in the first year, the twining shoots of solitary plants reach 4-6m height, and should then be reduced to one stem per wire rope and unwound from the rope (see below).
Unwound Wisteria shoot guided parallel to the wire rope, in winter. This shoot is now trained as a main stem with short side shoots; the fastenings have to be checked regularly in the following years, and if required, replaced. Continue below.
A year later, after defoliation, the entangled shoots need to be disentangled again and pruned. The fastenings on the future main stem are replaced. Continue below.
At wall brackets along the rope, the stems are slightly bent and guided around in an arching form to prevent the plant from growing into the brackets in the future. Continue below.
After completed maintenance: here the fastening was done with flexible and adjustable vulcanised india-rubber bandages. Some emerging flower buds can be seen on the side shoots.
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Two ancient Wisterias |
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Wisteria on wire rope. Two single stems develop such lush foliage anew every summer! |
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Stainless steel growth support with generous distance from wall. |
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Already after 10-15 years such trunks can be expected in Wisterias |
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Ingrown balustrade rod. Rod-like growth supports cause less building damage than ropes, nevertheless permanent entwining is to be avoided. |
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As an alternative to expensive growth support systems, pre-trained solitary specimens can be planted and trained onto columns or similar, and fastened with flexible velcro tape or elastic bands.
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