One stem, trunk, is good but several will work just as well. In your climate winter kill shouldn't be an issue so I'd probably go one trunk. Once the vine is on top the system you use is dependent on how much area needs coverage vs how much the canes grow each year. The simplest system is to prune like you would a normal vine. Head off your trunk in the middle of the arbor. Hopefully you then get at least 4 canes off the head. Position as needed for coverage. Those canes bear the next year. The following winter prune back as much as possible while still retaining 4 new canes for fruit the next year. The difference between normal and on top of arbor is how the canes are positioned. Normal they run down wires in two directions. On the arbor the canes are positioned so new growth covers area needed. They may pinwheel out from the head. You might have two heads depending on shape of arbor and area needing coverage. Once you get the feel for it pruning grapes is a lot easier than describing it.

Hi Carol, I have a grape vine that I will have to prune too. I am new to grapes and just moved it last spring, so I'm not sure whether I should let it grow and establish itself this year, or prune it first thing. I do think any pruning in general would be better off late in the winter, because with our crazy weather this year and the warm weather during winter months, I wouldn't want to encourage growth before spring. I think this unseasonably warm weather makes us feel like spring is around the corner and we get itching to get out there and start gardening (g).

nice looking vine! I'm as clueless as you say you are about grapes, but, I know the old, fruiting canes don't re-fruit the following year. Heck if I know what the old canes look like, so, I just cut back a little of everything. This way, the new growth from last year will fruit. If you cut back the new growth from last year too much, nothing will fruit. If the canes are long enough from last year's growth, they will fruit. It might take another season for your young canes to bear fruit. Sorry if this is confusing. I just cut back a little every year and let it grow on and not worry too much. I'll let the "vintners" out in Calif. worry when they're making my wine. :-)

well, likely as not either the vines grew or they didn't by now. Yes, grapes can bud from the side of the bark where no bud is evident. If you pruned them late, then you should not remove more than 1/3 of the vine if you want grapes this year. Don't know where you're at, but if Black Rot is a problem, then I would switch varieties. Here in the East, seedless grapes are very hard to grow without a lot of spraying. Most sucess has been with varieties that originate in NY state.