Get yourself into a good pruning routine with wisterias. Pruning twice a year, will ensure the flowers will continue to bloom year after year.
In summer, prune the excessive growth back to let the wood ripen. This increases the likelihood of flowers forming for the following year. In February, shorten the shoots again, tidying the plant up before growing season begins in spring.
Begin regular pruning to encourage flowers to appear. Ideally, once it has covered the wall, garden, or pergola.