How hard can I prune a large wisteria, and when should i do it?

[juslh]

I have moved house and inherited a large, tangled wisteria. It has wrapped itself round and round an old arbour that is rotten. I think the wisteria is all that is holding the arbour up! I want to keep the wisteria but not the arbour but not sure how to proceed, and I'm nervous about doing too kmuch to it for fear of killing it. Any advice as to how hardy is it and how hard I can prune it?? Many thanks.

[Thelma Sanders]

You'd have a job killing a big'un
RHS says

Drastically shorten back long branches, removing sections of older stems to just above a strong young branch or growth shoot lower down, or cutting completely back to a main branch, or even to ground level may be necessary. A careful, unhurried approach is needed if larger, thicker branches are to be removed and where a branch is twining it may be necessary to trace back and mark it at intervals with string before removing it. The end result should be a skeleton frame work of reasonably well-spaced branches.

https://www.rhs.org.uk/advice/profile?pid=242