Wisteria is high-maintenance to keep it looking neat! I had a one that didn't flower for five years but otherwise was very healthy and grew vigorously. A neighbour, who was a keen gardener, advised me to strengthen the roots by feeding it fish bone meal. In order to support the flower and leaves it will need a large root system to supply enough nutrients to the upper canopy of flowers and leaves! I did this and it became a magnificent plant, I trained it to run along wires the full width of the house. I would say I was pruning it at least 3 to 4 times a year to keep it in check!