Eight Year Old Wisteria Not Blooming — What Can I Do?

Question

Hi Garden Experts, Attached are images of my white wisteria. I don’t know why I’m sending you two shots. They’re very similar. Sorry, I don’t have a picture of it in the summer with healthy masses of leaves. But, as you can see by the branching, it does very well in full sun against a brick wall. The photo was taken today (Saturday, March 21). The place from which I ordered it claimed that it was grafted onto a three-year-old stock. I’ve had it for five years. That allegedly makes it at least eight years old. The problem: It has not bloomed — ever!!! I’m aware that it should have phosphorus, but I’m reasonably sure that the plant food I gave it last summer contained large amounts of it. Questions: (1) Does the warm-to-hot brick [summer] wall have anything to do with it? This thing grows aggressively every season. I think the wall is not a problem. But what do I know? (2) Do I really have to wait 15 years for this thing to bloom? I read of this possibility in several places on the internet. (3) If I cut back the roots to try and force it, what is the best time of year and how much of the root system should I cut. My appreciation in advance for your suggestions, -Milton Zelman [e-mail] Aiken, SC 29803

Answer 1

These are not reliable blooming plants. At all. They can flower one year, and not the next. Sometimes they will wait some years.

Depending on the quality of the place you purchased from, and actual age of the plants, you may have to wait 15 years, or even more!

There are other possibilities, though.

It could be that you have too much nitrogen in the soil, or the pH is too low to promote flowering.

If nothing else works, try root pruning with a shovel in early Spring. With a mature vine, that is healthy, you can move out 3 or for feet from the trunk and sink the shovel down into the earth all of the way around the plant.

There is a possibility that the soil is too fertile, as well.

Here are some articles that will help you:

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm

https://www.gardeningknowhow.com/ornamental/vines/wisteria/wisteria-blooming-problems.htm

https://www.gardeningknowhow.com/ornamental/vines/wisteria/growing-wisteria-proper-wisteria-vine-care.htm