My white wisteria blooms well while my purples only leaf. They're getting plenty of water and sun but no flowers. The purples are over 3 years old and have not flowered.
What Can I Do to Get My Purple Wisteria to Bloom
Hopefully, this article will help: https://www.gardeningknowhow.com/ornamental/vines/wisteria/wisteria-blooming-problems.htm
I had a fourth generation nurseryman tell the story about his grandfather advising a gentleman to "Whip the stuffing out of the vine with a leather 'strop' " the fall before his daughters wedding. By all accounts, he did and the plant bloomed beautifully for the wedding. Have also heard the same method used on fruit trees. Don't know if it works...