Most of the time our hand-wringing about wisteria bonsai is when an otherwise happy tree won’t bloom. They can be obstinate and willful. Last year I wrote a post about a few basic wisteria concepts, Why Won’t My Wisteria Bloom? While those ideas might help getting some plants to bloom, when your tree gets very mature, be awake to another problem: A wisteria that only blooms and does not grow tendrils.
If you’ve a wisteria that blooms itself nearly to death, puts out a few leaves, and then sulks there the rest of the summer, you need to get out the bull whip. Or a least some good loud music and seriously bump up your fertilizing. I had a small tree last year that put out a ton of blooms. I cut 2/3 of them off, and it did not put out a single tendril the whole year. This year it tried the same thing, and I said, ‘No you don’t, you’re going to kill yourself with sex’. So I cut ALL the blooms off (I hope I’m not horrifying anyone with a wisteria that won’t bloom), put on a lot more organic fertilizer pellets, and now I’ve got half a dozen tendrils noodling their way into the air.
A tree that does not grow—and you may see this on any very mature tree: juniper, quince, or vine—cannot develop. It won’t grow enough to develop branches, or more complex ramification. Worse, sometimes such a tree will lose ramification. It’s just hanging out there, lounging on the bean bag, drinking beer, getting obstinate, slack-jawed, and willfully unproductive. Most of us do not have this problem with wisteria. We’ve the opposite problem, reigning in a wildly growing plant. Which, for the most part, vines are: Totally untamed wild things of the plant world.
Much of bonsai care is ‘nudging adjustments’. You waddle around your bonsai yard looking carefully at each tree, trying to notice what each is doing. What type of energy it has, and deciding if you agree with that direction. Then you might add some fertilizer to a tree, or take some off, or reposition the tree for more sun, or less sun. Or bring out the podium and place it in front of your wisteria—or some other plant, like a quince—for a long lecture on flowering too much and growing too little. They are patient with such measures, plants are, for the most part. It’s your neighbor, leaning over the fence, who has a worried look.