Question
I am from Central Ontario Canada and need to know when is a good time to cut back and how far. It is a five year old plant which has become a tree almost.  Thank you

Answer
Hello Sally

Ideally Wisteria needs to be pruned twice a year - November/December and August.

When you prune at the end of the year you should cut off all those long tendrils by about 1/3 and reduce the spurs which carried flowers in the summer to about 4 inches from the main branches.  

The following August, when flowering is finished, cut back the spurs to within 6 inches of the main branches leaving 4-6 leaves on each shoot.

As your plant hasn't been pruned at all and is now well established, you could either leave it free standing (like a tree) but cut back the growth quite hard in August and encourage it to keep (or establish) a nice 'weeping' form, or put up some sturdy supports and encourage the growth to goes outwards from the main trunk by tying in some of the lateral growths (the tendrils).  I think I'd prefer the first idea!

If your Wisteria is very near a wall you could fix supporting wires to the wall and train the tendrils along them, taking out any growth that starts to grow inwards towards the wall and outwards away from it, keeping only the growth naturally going sideways along the line of the wires, tying it in as it grows.

Whichever form you choose the pruning rules remain the same.

I hope this helps.

Gill