Wisteria

Winter up to March, during a frost free period,  is the time to prune a Wisteria to promote flowering.  The pruning needs to be done a second time in summer to contain the season's growth.

1. A Wisteria flowers on the branches of the previous year.  The way to tell the previous year's growth is that the bark of the branches is bright green and has flowering buds.  Growth and flower buds are easy to distinguish in late winter, the former being narrow and pointed, the latter plump and blunt.   Shorten the branches till they are 30 cm long, make sure that you are left with 4-5 buds.  Don't prune the twigs at the base, they are going to replace the branches.  Cut back the old side shoots to two buds, so that they can develop into flowering branches the following year.  
2. Once the pruning has been done, clear out all the dead wood, as well as the growth that appear at the foot of the plant.  If you like to have the trunk free of growth, cut back all branches till required height.
3. August is the time to remove unwanted growth.  Cut back the new shoots by half and remove branches that spoil the overall framework of the Wisteria.

Bibliography:

Rustica 

RHS:  pruning