It sounds like you may be giving your wisteria too much nitrogen. What sort of fertilizer did you use in the past? It might be best to just lay off adding any more fertilizer for a year or so, then use something with a lower percentage of nitrogen compared to the phosphorus and potassium.
“Think occasionally of the suffering of which you spare yourself the sight." ~ Albert Schweitzer C/F temp conversion
Just wondering now... Wisteria needs full sun in the spring and in the summer months, not much now. Can you remember if it was getting full sun back in spring-summer 2021? Most hydrangeas tend to balk at growing in full sun conditions and those that do thrive in morning sun only.
Yes. My Hydrangea doesn't like it there (my wife planted it). Wisteria has always been in full sun with a southern exposure. It is incredibly prolific with an abundance of foliage. Just no flowers. When I moved here 30 years ago, the display was breathtaking. I would hear the crack of the seed pods and the tinkling of the seeds falling to the ground. You could smell the fragrance from a distance. Slowly over the years it became less and less. Now I have 10 - 15 trash cans of foliage cuttings 2 or 3 times a year. But no flowers and no seed pods.
Can you tell us more about the fertilizing of the wisteria as well as about the soil? Bone meal usually has a NPK of around 3-15-0 on average (varies from one product to another) so it is low nitrogen. Do you fertilize the wisteria with anything else? Does anyone fertilize the area nearby, such as some lawn fertilizer? If that fertilizer gets near the wisteria, the high nitrogen content of lawn fertilizer could start to cause issues.
Have you ever done a soil test? Does your soil have any soil deficiencies or toxicities? Is it sandy?
Can you comment on the watering program that you use in the spring and also the one you use in the summer?
Have you already tried root pruning it? This is done by taking a shovel and driving it into the ground in a circle around the wisteria and at least 3 feet from the trunk (root pruning too close can kill the wisteria).
This is a lot to answer and I think I need time to investigate. First of all, this is old wisteria that was there before I developed ground around it. So, I definitely changed the environment. Little of the root structure is available because it backs up to a slab and a sidewalk on the other side. I am not sure if root trimming is even possible. It is essentially rooted in a 2 x 2 planter box. Both slabs were there prior to me moving in 30 years ago. There are planters near by that have the plants described. Let me do some soil tests and see if we can narrow this down.
They say to give the vine a good root pruning to shock it into blooming... Make it think it's dying.
I haven't personally had success with that method, but they're impossible to kill...
The only way I could get wisteria to bloom at one garden... I rooted a vine that bloomed...
They're so common and invasive here... real easy to find one to root... Just cover one of the adventitious suckers or other runners in a pot of soil long enough to produce roots... and then cut it loose... plant whenever.
That house that had the non-blooming wisteria? In 15 years, It never did bloom... whereas... the one I propagated & planted next to it? bloomed plenty. I found one that produced blooms out of season to propagate... If you're gonna grow invasives... at least try to grow ones with desirable characteristics!
Name: brenda reith pennsauken, nj (Zone 7a) nature keeps amazing me
a friend gifted me a wisteria. it had a single bloom on it. and never bloomed again. I will admit it was not planted in full sun, as I told him to do. after 15 years of constant pruning it off the gutters and fencing I dug it up and that was the end of it. They're a beautiful vine-the scent is heavenly! but also a strong willed grower that can take down a structure. a friend lost his pergola to one. most vines are tough to get rid of although I don't know if wisteria classifies as a vine.