At University, around exam time, it was a delight to see the flowers of the fragrant Wisteria sinensis adorning the ancient buildings. I don't have a picture of the wisteria inside the college court, but here is one across the road (at Sidney Sussex College). Little did I know that 40 years on I would be up a long ladder pruning wisteria in Stoke Bishop, Bristol (my home city).
Wisteria is a plant that requires four dimensional thinking and application (Wittgenstein, one-time inhabitant of the court-with wisteria would appreciate that, I'm sure). By the fourth dimension, I mean time. When you plant your wisteria (which should, ideally be in a southerly or south-westerly situation), you must imagine the shape and spread you would like to see, and construct a wire trellis (using 3mm steel wire) in the shape of the grown-up plant. Then, each time you prune it, you will train it towards its final splendid form. If you chose "sinensis" (which is probably best for walls), position the wires at least 1 foot apart (because the panicles are up to a foot long). You should also consider how you will prune it once it's climbed up the wall. Yesterday I used an extending ladder (to 15ft) to prune a Wisteria covering the whole of the back of a large house, and it was a challenge finding a ladder position to get to all of it.
There are two prunings needed for the Wisteria. One is in July or August- after flowering. The purpose of this prune is to retain an open and shapely structure to the vine, prevent any nuisance growth (such as into gutters and along pipes) and encourage the formation of flower buds (rather than just leaves). In this pruning, you should cut back the whippy green shoots of the current year's growth to around 5 or 6 leaves. However, you should leave, unpruned, the shoots that you want to train along the horizontal wires to provide the future branch structure of the vine.
The second pruning is in January or February. You will need to cut back the previous year's growth (the shoots you pruned back in July/August) to 2 to 3 buds. At this stage you can ensure that the new shoots you have left to train into the future branch structure are properly aligned along the wires.
Happy pruning!