...using the logic of ecology

pruning wisteria in Italian gardens

Wisteria, like so many other flowering climbers, requires regular pruning if it is to provide a satisfactory annual flower display and maintain a tidy and compact form. Nevertheless, wisterias are all too often allowed to romp and sprawl over pergolas and houses, simply because their owners are unsure as to how a wisteria should be pruned.

So, what is the best way to prune a wisteria?

Well, I am often confronted with wisterias that require a drastic, renovating prune because they have been allowed to grow for years without so much as a single prune. In such cases it is essential to remove a large percentage of the excess growth and I find that the best time to do this is in Italian gardens is immediately after flowering, usually towards the end of June or the beginning of July.
In this period one can remove dead or un-productive wood and the wisteria’s lateral (side) shoots can be pruned to about 30cm from the main stems. This pruning stimulates the wisteria to produces masses of new, vigorous growth that will shoot in every direction. Some of the strongest shoots amongst this new growth can then be trained over support wires to create structural growth and will quickly make up the area lost through pruning. However, those shoots that will not be used for creating structure should be shortened to around 2 or 3 buds throughout the summer to stimulate the production of flowers spurs.
Although this new growth doesn’t always produce flowers in the first year, it often does and will occasionally flower spectacularly, even in the first year after pruning. Nevertheless, one can be guaranteed of masses of vigorous new growth that will need pruning again at the end of the first flowering season.

Annual wisteria pruning

Wisterias in Italian gardens should have their lateral stems shortened to around 30cm after flowering in July and any unwanted growth should be shortened or removed. These 30cm ‘stubs’ should then be shortened again to around 15cm in December as this will create what are known as ‘flowering spurs’, from which a profusion of flowers will appear every spring. By reducing the annual growth of the wisteria back to the flowering spurs in this way one can ensure that the wisteria not only produce masses of flowers but that it will remain tidy and compact.
In the slideshow, to your right, you will see a series of photographs of a wisteria prune that I was asked to perform for an ancient wisteria at the famous La Foce gardens in Italy. This particular wisteria was ancient and had been badly neglected but, as you will see, it soon made a notable and very vigorous recovery from the renovation prune.