Grafted wisteria tree

We planted this tree early summer, recently been told that as its grafted its twined trunk wont grow thicker with age and get stronger, meant to be more for leaning against a pergola type structure. As its not got this kind of support to grow over its open to elements, Concerned with high winds at times. Is this true? Does any of you have experience with this kind of tree?

 

Warning! Im no wisteria expert!! Warning!​

I'm having trouble working out what's happening in the photo, so please bear with me!

From what I can make out, you have a wooden framework with a single wisteria stem wrapped round it.... the wisteria is wrapped around a central pole, going up to a 4-way "star" at the top, where it has been allowed to sprout. The whole thing has a simple brace at the bottom....

First of all, many plants are grafted, and the trunk/stem gets thicker, both above and below the stem. Think of fruit trees!
As I understand it, most wisterias are grafted, as cuttings are slow to flower, whereas grafted plants will flower when the grafted-on section is still relatively young. So they take their "what age to start flowering" from the rootstock, not the graft.

Wisterias are basically climbers, not trees. They can be grown to be freestanding, but it takes many years of supports, careful training and pruning to achieve this. I'm thinking of a stunning wisteria "tree" in the palace gardens in Laken, Belgium. The plant is over 100 years old...

My main concern is that it is a single stem, rather than two stems. So if you imagine the shape of the plant without the supporting framework, you have an open, stretched "spring" stem, with a weight of flowering growth at the top. In any material, this would not be stable without the support. It will need some sort of framework for another 10-20 years, in my estimation, before the stem expands enough to be strong enough stand without support, and then only if there is not too much weight on top.

So, you need to keep the framework in place for a number of years yet, and be ready to find alternative ways to support it, should the central wooden stake fail/rot. It needs to be in a relatively sheltered place, certainly not exposed. The whole structure would probably be happier in the ground, rather than in the pot. This would let the plant grow stronger lateral roots, and brace itself, with time.

 

Sian thank you for such an in-depth replie! Ive attached 2 more photos, as you can see i have had to tie temporarily a washing pole as we had sever gales earlier this week and the tree and bamboo that the trunk grows around was bowing! The bottom of this very large pot is hollow so roots can grow further down into the ground also. But after what you have said i may have to rethink an alternative area for this to be planted

 

Oh dear! I was hoping the main support was something like a broom handle, i.e. Wood, rather than bamboo, which naturally bends under pressure.

Yes, it definitely needs serious supporting, not just a bamboo cane against a brace. One thing you could do would be to get some pressure-treated wood (so it won't rot) and put an additional vertical support at the end of each point of the "star". So in effect, you have 5 vertical supports, making a box. These would need to go down the full depth of the planter, and then up to the end of each star point. It would make the structure much more rigid. Diagonal braces as well? Guy ropes coming off the top tie-point, down to the corners of the planter? If you're a belt-n-braces type?! I know this sounds a little extreme, but you are trying to give the plant the same sort of stability that a pergola would give a "normal" wisteria. If done sympathetically, it doesn't need to look too bad - and better than a blue washing pole! You could even grow something like sweet peas up these "box walls" whilst the main stem gets stronger.

But it will take a long time, and ideally should not be in a windy position. The wind would rip through the spring flowers, is nothing else!

(And you can probably tell, I'm a bit of a waffler - made worse by being an expat who is limited by her Dutch fluency on a day-to-day basis!)

 

I was just looking at something like this, they always come flat pack and i could build this around it, plus as the washing pole was temporary i may pick up a new bamboo, can get really thick ones.

 

Got to agree with @Sian in Belgium the support will never take the weight of a wisteria.
The archway you show would be much better.