United Kingdom 
What part of Wisteria do the flowers bloom is the leaves or the long winding stems? How do I prune them to promote more flowers the leaves or the stems? Also do you treat the white wisteria the same as the lilac one when pruning? Thanks
18 Aug, 2011
They bloom on spurs on the lateral (side) growths - assuming you've topped it out at the height you want, all the other growth should be coming out sideways off the main stem/stems - shorten these now by at least half, and some within 8 inches of last year's cuts. Cut again in mid February, shortening them to within 2 inches of the cuts you make now. You can sometimes see very fat buds nestling in against the stem by mid February, as well as smaller buds - the fat ones are flowers, but if the weather is still cold, you can't always tell.
19 Aug, 2011