Wisteria look and smell gorgeous when covered in flowers in late Spring/ early Summer but can be a bit reluctant to flower and have thuggish tendencies. To get your Wisteria behaving as you wish it needs pruning twice a year.
At the end of July/beginning of August all the long whippy bits of new growth, not needed to extend the framework, need shortening to about 5 or 6 leaves. Snip it off just before the leaf joint so it looks tidy. If the new shoot is growing where you really don’t want it, for example from the bottom, just remove it completely. The plant will still look lovely and bushy, just less out of control! In a warm, sunny Summer the plants will often then reward you with a smaller, second flowering.
The second prune is done in early Spring whilst the plant is dormant. Here the sideshoots are reduced to a couple of buds leaving a clear framework ready to leap into life once Spring arrives.
Wisteria before Winter pruning Wisteria after Winter pruning