Hardy Tropicals UK

When Fargesias are fully grown what is the typical diameter of their clump if they have been allowed to grow unrestricted by any obstacles?

I have plans to plant a "bamboo path" next year using Fargesia Robusta and Murielae. I'm wondering how far apart can they be spaced so that they will eventually create a dense screen, I don't want to plant them too close now and end up having them stunted/strangling eachother. I would be planting them from 5litre pots.

a running bamboo might be better because you could just mow the shape of the path through it

I know but in this case there are neighbours with only a fence between them. I don't want to use barrier since the bamboo will either escape or become a tangled mess long term.

I think they continue to slowly expand until they flower and die. I don't think there is such a thing as a fully grown bamboo. It is either growing or dead.

As we don't know how long they have until flowering, then there is no way of knowing how big they will get.