How to Get Wisteria to Bloom. Since too much nitrogen is the most common cause of wisteria blooming problems, the easiest thing to do is to make sure this is not a problem. There are two ways to correct this cause of a wisteria not blooming. The first is too add phosphorus to the soil.This is done by applying a phosphate fertilizer.sing root pruning as a way how to get a wisteria to flower reduces the amount of roots and, by default, the amount of nitrogen those roots take up. If these methods do not work to correct your wisteria blooming problems, you can check to see if one of the other reasons may be the problem.