I have a wisteria that's about 10 yrs. old and has never bloomed. What do I need to do to make it bloom?

Wisteria floribunda or Japanese wisteria is probably the most common wisteria found in the nursery market. It is a beautiful flowering vine (once it decides to flower) but you need to make some hard decisions before you decide to put this plant into your garden. Wisteria needs a VERY strong structural support. No namby-pamby wood structures for this plant, use heavy metal or watch you wood structure be crushed under the pressure of the wisteria. Cultural practices for this plant also must be fairly rigidly followed; otherwise you’ll find yourself with a rampant, vegetative mess and no flowers. Wisteria sinesis is the Chinese wisteria, similar in habit and flowering period to the Japanese wisteria. You may want to spend the extra effort to find an American Wisteria or Wisteria frutescens or Kentucky wisteria, Wisteria macrostachys; these species are not quite as rampant growers.

The two most common problems with wisteria are 1) it grows too wildly and 2) it won’t bloom. Coincidentally, the solution to both problems is the same.

Wisteria is a very, very aggressive vegetative grower. It will start form just a shoot or two in spring and quickly turn into a tangled mass if not controlled. Regular pruning will make for a much more manageable plant and it will encourage blooms. If you prune your wisteria when it is young, it will start the bloom process much sooner than if not, but keep in mind that wisterias still may take as long as seven years to bloom.



Wisteria will refuse to bloom if it is over fertilized with high nitrogen fertilizers or of it is too shaded. But the most common reason that wisteria won’t bloom is lack of proper pruning.

To properly manage your wisteria vine just keep saying to yourself, “Because they are such vigorous growers, they should pruned several times a year.” And then do it!

If your wisteria has been neglected, it is best to start pruning in late winter or early spring. Gather your good leather gloves and sharp pruners and if the limbs are thick, a good pruning saw and a pair of loppers. The basic idea for most situations is to create a single trunk with just a few branches, spaced a foot or so apart, at the top of the plant.

(If the plant is hopelessly overgrown, you can cut it back to the main trunk. Even though this may seem a bit severe, the plant will recover, sending up the choices for those few branches with good time. And though the plant may not bloom again for a couple of growing season, what good are the blooms if they are hidden under the tangled mess of stems and branches?)

Once you have your winter pruning done and the plant is fairly under control, regular summer maintenance will keep the plant in hand. About two months into the growing season begins, cut back each of the shoots on your chosen branches to about six nodes. (Nodes are where the leaves join the stems.) If your wisteria is mature and blooming well for you, you should do this pruning after the flowers fade. Later in the summer or fall, remove the stems that have grown around each other or that have become overly long, shortening these back to six nodes or so, or 10-12 inches, whichever way is easier for you to measure.



Another maintenance measure for spring time is to remove any root suckers. These actually have to be dug up in order to control them. Cutting them or mowing just makes them worse. Trace back to where they emerge from the main root then clip them off at the source. These shoots will easily get out of hand without digging and will sap your plant of strength.

Prune again in late winter to early spring, cutting the side branches back to size again. You should see fat flower buds on these stems and with any luck, you’ll be enjoying those big beautiful flowering racemes in just a few weeks. It is also okay to prune your wisteria to a tree form, it just takes more of the same pruning.