Cause 1: wrong place
The wisteria likes a spot in the sun or partial shade. Less than six hours of sunshine per day will not make him happy. The east, west or south side of the garden or facade is therefore perfectly possible. If the Wisteria is in the shade for a large part of the day, no flower buds are formed.
Cause 2: poor soil
The Wisteria likes humus-rich soil. So pamper him with extra food. Also make sure that the wisteria is not too dry. In the open ground it can take a beating (read: wind and weather), but if the wisteria is in a pot, you have to protect the root ball in a severe winter.
Cause 3: not pruned
If you want the wisteria to bloom profusely, you should prune the creeper twice a year. If you don’t do this, the plant will become a tangle of thin branches. He then puts all his strength in the growth and not in the flowering. Pruning is done in the winter and in the summer. You do it differently both times:
In January or February the Wisteria is still bare and you can clearly see the shape. You then have to prune back all side branches to two or three buds. Preferably on a frost-free day and with the use of sharp, clean secateurs, to prevent infectious diseases. Leave the main branch alone, unless the wisteria is really getting too tall.
In July or August you prune the wisteria again. Cut all side branches back to within six inches of the main branches.