I pretty much ignore mine. I am smack in the middle of Washington Wine Country, so when I see the field workers pruning the acres of vines, I prune mine, too. No fertilizer, they get that from the lawn fertilizer, mostly. I do put a good thick layer of grass clippings on for mulch. The silly thing grows all over its allotted space and heads off to visit the raspberries. I do try to thin out most of the grape clusters in hopes of getting larger bunches, but I never seem to pick enough of them off - so the birds help me out.
The old vines get chopped off in the spring to be used as peas supports, works great.
