Your wisteria (Wisteria sp.) isn’t blooming? Or at least not as heavily as you would like? Here are some solutions:
First, be patient: most will only begin to bloom with any real abundance in their seventh or eighth year. Also, you have to plant them in full sun and, in colder climates, in a spot protected from the wind. But above all, you have to mistreat and neglect them. Give them truly crumby soil: mineral-poor, stony or sandy. Avoid fertilizing, especially with nitrogen-rich fertilizers (the first number on any fertilizer package should be close to 0), because nitrogen stimulates the growth of stems and leaves at the expense of flowers!
If in spite of all your negligence, your wisteria has not bloomed after 10 years, it’s time to be even more sadistic. With a very sharp shovel, cut all around the plant in the spring, about 18 inches (45 cm) from the stem, thus severing many of its roots. Such an apparent massacre often has the effect of stimulating a massive bloom… but only the following year!
Once a wisteria does get going, its flowering is usually pretty faithful. But considerable patience is required!