increasing vine trunk thickness........ prune or grow?

[Joe Dupre']

I have a couple of root sprout volunteers from my big trumpet vine that I dug up a couple of years ago. They are about pencil-sized and I want the trunks to get quite a bit bigger. I've heard differing opinions on getting vine trunks bigger. Anyone had any first-hand experience with vines in general? I'm willing to experiment with the two plants I have.

 

[Gabler]

If you want to increase girth, you should let them grow as much as possible.

 

[Shibui]

As far as I'm aware vines are much like other trees - Growth = Thickening.