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.

I think the best time to prune in areas with freeze danger is in spring just before or as growth begins. I think this is too early in zone 7. I'd take cuttings for rooting 2-4 weeks before growth begins. Then they may need to be buried or stored in a cool place until rooting. It depends on whether you can control temperature or are reliant on nature, they need warmth to root rapidly. I'm not an expert on rooting grapes but have done it many times. Usually by just planting them where I wanted a vine, covering until spring, and then uncovering the top bud. This works but there are ways that result in much higher % takes. The key to rooting them is getting callus formation first. This works best at warm temperature, just the right moisture level, and rooting hormone. The cutting needs to be fully turgid but not wet. Some experts callus them in moist sand. This months Good Fruit Grower has an article on rooting grape cuttings. I've never used rooting hormone so that's not essential.

Linda, I cut a green (not dormant) vine about as round as a pencil, approx. 12" long with at least 3 nodes. I cut the vine with the bottom node as the bottom of the cutting. Make sure you know which is the top and the bottom of the cutting. I immediately soak the bottom node just to make it damp enough so the rooting powder sticks to it and plant it in a small pot filled with potting soil with the bottom node and wood in the soil up to the next node. I have a 14" pot that I put 5 cuttings in, Another 8" pot that I put 4 cuttings into, etc. I have pots for all varities of grapes labeled. I keep the soil moist but not soaked. I make sure the pots are in the sun long enough to keep warm but not hot. In a few weeks you will see green from the exposed nodes. Linda, this is what I do with complete success but I would suggest googling propagating from grape cuttings to find out the proper way. I'm probably doing a half dozen things wrong but it works for me. Good luck, John

Hi Spartan apples, thanks for the interest. Sorry for any gaps in the narrative, I posted previous bits and pieces on another site. However, the people in the know are either busy in their gardens or not very friendly, as I'm getting the silent treatment. The runty grapevine was actually bought and planted at the same time as the big one. They were both transferred into the ground last spring. The small one had to be emergency re-transplanted mid summer, to its current location. I believe that's what caused the stunting, although I thought it would return to normal vigor this spring, which it did not. This may be a permanent phenomenon? Summer pruning of the vigorous grapevine, it sounds like people just cut it wherever to improve airflow and get the shape thereafter. Leaf to vine to location on the vine ratios, in order to maximize production - I get the impression these are not clear for most people, so there isnt any clear guide online at least. Let alone transposing those to an actual living vine. I bought and planted the peachtree last spring. The central trunk had been cut quite short and it had a few small branches coming off. I believe it was the vase style you describe. It was about 3 feet tall and sparse. It grew very well, filled out, and was about 6 feet tall by the end of the season. I did no pruning until the spring, and only removed partial branches that had been damaged from OFM the previous year. This year it flowered and fruited profusely, and is growing much larger already. I have bagged many peaches on it. I think they'll ripen up in August. Not sure if I have to prune the tree in order for the fruit to ripen better? I know it might be a good idea to prune branches interfering with the grape trellis. However, the grapes could be repositioned in the future, while the Peachtree cannot. I just want to maximize production. At this point, I'm thinking to chop out a few of the center branches and a couple of the interfering branches on the trellis, just to get a bit more air circulation. Can't see the point of getting sun on the peaches, as they are bagged. Is the correct procedure to cut the entire branch off at the node where it springs from the parent branch? By the way, that's nice your wife was in Japan before, I hope she had a good experience. I originally came a bit after that, in 1999. I'm not too far from Kobe.