40 year old grape vine, need help with cutting it back.
So I have this grape vine that has been here at this house before my grandpa owned the house, I been told by my mom that it was part of a vineyard.
It has been producing fruit but it hasn't been pruned or maintained at all from what my mom has been telling me.
This year I want to rebuild the trellis completely and cut back the grape vine. I been reading that if I have a over grown grape vine I could cut it down to nearly the ground and it would regrow. As you see I have too many main trunks and they all split. I would like to only have one main trunk and grow it either straight up or spiral around a post and into the new trellis.
How should I go about with this particular grape vine?
Do I keep cutting one trunk down until it stops growing or try to merge them after they grow a bit?
I'm really lost in what course of action I should take.