wisteria not flowering

Hi, my neighbour asked me why I think his wisteria hasn't flowered very much this year. It is quite a size and a few years old. I thought it might benefit from a pruning to encourage flowering but I thought I would ask you guys first. Any thoughts ?
gazania

 

A summer prune back of the long shoots helps to form flowering stubs on the stems of established plants.
I used to cut these back to about three or four leaves about now.

 

My wisteria hardly flowered until I pruned it properly but I've had a great display this year.

In August, cut the wispy tendrils down to within six nodes of the main stem. Then in late Jan/early Feb, cut them down to within two nodes of the main stem

The pruning enables the plant to put all its energies into forming buds rather than making the wispy tendrils.

 

Thanks guys, I will pass on the info today.
gazania

 

We have not had much sun either really untill the past week or so i doubt that has helped