Grapes actually don’t need a winter dormancy period. They grow at the equator without it. I will probably set up to grow year round in the greenhouse, with supplemental lighting during the winter. I would have to make sure winter growing is economically feasible first, with the higher electricity needs.
Forgive my ignorance; I'm not even sure if you could wake up a grape vine over the winter or if they need to hibernate for a period of time.