To keep Wisteria tidy and flowering, well its best to prune twice a year.
Winter pruning will encourage more flowers. Make sure you cut back each stem to 3 or 4 buds, leaving short, stubby growth called spurs.
This is also the time to tidy back any long shoots that have grown out too far from their supports.
A summer prune in August will tidy the plant ready for winter. Cut stems back to roughly 15cm (6 inches), or tie the stems in if you want to expand the courage of your plant.