There is a lot of factor before a wisteria blooms specially if bonsai. First, it should be mature enough to give flowers...cutting is not recommended if you want it to have flowers soon. you have to take consideration of the condition of the plant too, sometimes some of the variety love to be root bound in the pot before it will flower, it love water and full sun.

Now is the time wisterias are budding. Flowering is not far off. Do you think yours will flower this year? Everything sounds good though. These plants are very difficult to kill, even when you want to. One thing you may consider: the main branches that come out and lengthen are amenable to training if you desire to do so. You can create twisty trunks or twine them together, or do just about anything with them for an aesthetic effect. In a barrel planting, you may want to train yours as a "standard", which means a single trunk (or several twining branches making a single trunk) with the foliage and flowers as a clump on top. This style is very pretty when done right. Wisterias do need pruning at least twice a year, mainly the whippy branches that grow and grow and grow. There are some good wisteria books, probably available at your local library, you might want to check for detailed pointers on pruning & training. Have fun.

IME, the flowers are very susceptible to the vagaries of the weather - mine got hammered this year from the windy rainy week, then the ungodly hot week; it was clearly not a combination they liked as they, like yours, fell apart quickly. They aren't long-lasting flowers at best, not like a columbine's flower is, but they usually last longer than they did this year. So, chalk it up to the weather and wait for next year (also known as the Cry of the Gardener).

I have to disagree with you about the 'tree types' of wisteria. They are all strictly speaking vines. There are two main types...Chinese or Japanese. You can tell which type a vine is by the direction it naturally curls when it is twining up a support. A 'tree type' wisteria is a wisteria vine that has been carefully pruned to control the way it grows and to head back growth until the 'tree' has the shape that is desired. This pruning must take place several times during the growing season. Also to maintain the tree-like appearance, any new vines/runners that emerge from the base of the main trunk must be consistently removed or it will mar the appearance of the tree form that is desired. This is how I started my 'wisteria tree'. I planted seeds from some wisteria found in the woods near my home. I got really good germination as they sprouted very quickly. In fact, they grew so robustly that in a week or two, I had to pot them up to a larger container. I let it grow as it wanted for the first year. I staked it (onto a 5 ft. stake) as soon as it got about 2 ft. of growth on it. Of course by this time is is in the ground in it's permanent position. Then I began the training. When the growth reached the top of the stake, I lopped the vine off at the top of the stake. After that point, I only allowed lateral shoots to grow along the top 5-7 inches of the vine under where I cut it off. (Any growth lower I mercilessly rubbed off to as to have a really nice trunk later on) I let the laterals grow to the length it wanted that summer. In the fall I also cut them off at about 4 ft. These laterals will be the 'branches' and main structure of your future tree. From that point on, when new growth appeared, I would stand back and look at my 'tree' and decide where I wanted to pinch out/cut back growth so as to give it a nice shape. If there was a space that needed filling in, then I would allow a sub-lateral to grow on that was in that area and then head it back. When the tree had been fully shaped as I wanted, then all new grown was pruned to 2 spurs/nodes to give fullness to it's look. To create a wisteria tree is truly a labor of love. You must be a dedicated soul, because wisteria is a most vigorous grower and must be constantly managed or it will quickly get away from you and end up in a tree. I can tell you, if you really love wisteria, it is really worth the effort. My wisteria tree is now about 9 years old and it is stunning when it is in bloom. It is a show stopper. If I had anything to do over, I would start from a cutting, instead of seeds. Seedlings take about 5-7 years to begin blooming. If one takes cutting from a plant already blooming, of course you get blooms early on the growing of it. I hope this helped you. I'm sorry, but I do not have a picture of my tree that I share with you.