We have a Chinese wisteria that was planted in 2000 and a Japanese one that was planted in 2007. Both are grown as more-or-less trees. This past nasty winter killed the spring flowerbuds on both of them so no bloom this spring :-(. The Chinese one produces a small summer bloom if it is pruned regularly - a few flowers are appearing now but not many, probably due to our cooler-than-normal temperatures slowing growth a bit. We grow a white Henryi clematis into the Chinese wisteria and it is still producing a few flowers. We keep all the whippy/curly new growth cut back into the mass of the 'trees' in order to keep the trees neater and denser - cutting them back also promotes the summer flowers on the Chinese one - but I've never got summer flowers on the Japanese one.

Unpruned Jafanese wisteria:

DH pruning it:

Pruning the Chinese one (you can see some of the clematis flowers):

Chinese wisteria tree - we cut off about 18" from the top this spring to make it easier to reach the top with the long-arm pruners!