Be sure to listen to this show where Ken tells how to prune your wisteria to get more blooms...among many other interesting, entertaining things on this show.
Making Your Wisteria Bloom
All wisterias have some basic requirements, such as sufficient light, moisture, and a supporting structure on which to climb. But they are pretty forgiving about most such things. Assuming you’ve met the plant’s basic needs, here’s what I do to induce more abundant blooming at a younger age:
1. Prune immediately after bloom (if there are flowers) or in June as the rampant new tentacle-like shoots seek nearby supports.
2. Prune it again, in July.
3. Prune it again, any time up until mid-August.
Cut back each roving stem to a point where it has five full leaves. Cut just above the fifth leaf. (See illustration--click on it to view a larger version in a separate window.)
New growth will commence again, shortly. After a few weeks – or whenever you get to it – repeat the pruning process, attempting to maintain around five leaves per stem.
As the season progresses, you’ll be cutting back more on the “tendrils” and smaller stems, and less on the larger branches.
Let it grow for another month and repeat the process. Head back any branch or tendril with more than five leaves to just above the fifth leaf petiole. Now you’ll have several short, somewhat stubby branches or “spurs.”
Certainly, use your discretion and judgment. You need not cut back EVERY branch or every tendril. Prune what you can, and be careful if you’re climbing a ladder!
While this sounds like a daunting task, I don’t follow a rigid schedule. I’m more haphazard about it, tending to it when it crosses my mind. It doesn’t take long and you need not be surgically precise. The point is to encourage the plant to put its energy into developing flower buds for next year, not rampant growth this year.