Pruning a GH grapevine

So my Concord grapevine in the greenhouse is doing great. Came back to life about a month ago and is growing well. It has been trained up ~9’ or so to just below the roof of the greenhouse, and from there arms are headed sideways towards both ends. I’ve been pulling off buds which start lower down on what will someday be the main trunks, but have been unsure what to prune elsewhere. The ends of the horizontal arms are continuing along the wires. But there are quite a few vertical “side branches” from buds along the arms that are hanging down.

So far I have just left those vertical branches but if I don’t do something soon they will be reaching ground level. I assume that I should pinch off the growing tips of these to force them to become more bushy, and to put some more growth to the end of the main arms.

Any suggestions on an optimal length for these “side branches”? Oh, and there are some fruit clusters forming here and there on these side branches too…

Are the side branches this yrs growth or last?

Side branches are new growth this year, off of last years main arms.

I let the current season canes extend to the floor, about 8ft on mine. There are two curtains of such canes about 3ft apart. On each cane usually one cluster of grapes. I thin out the canes so there is probably one cane per ft of curtain. More canes or clusters might be appropriate under different conditions. When they reach the floor I just cut the tip off as often as needed.

Thanks @fruitnut. I am surprised that you let them go so long. I had actually planned on growing a few low things under them this year, so may have to prune the tips a couple of feet from the ground; but that is good to know for next year.

BTW, what is the recommended spacing on the fruit bunches? Sounds like you are giving each one 8’ or so of cane and leaves.

That’s all by feel and experience. Too much fruit will lower the brix. It’s just what you want. I can’t tell you about Concord.