I recently moved to home in Florida and the yard is overgrown with muscadine vines, which I would like to save! The property is on 1.25 acres and I have long farm fence I can use as a trellis or arbor. The previous owners planted about ten plants, but the yard has not been maintained and vines grew long and into the yard (covering the Brazilian peppers which I've been removing) . Most of the vines start at the fence line. The vines are skinny and produce small fruit, but run 50 feet or so. I want to know how much I should cut back or prune. Do I cut them off at the top of the fence line? How do I get them to "T" off? How do I know if I am cutting too much?
I think I understand that the long farm fence may have been the support for the previously planted vines. If that's not correct, let me know.
I wouldn't use the farm fence as a trellis. It will make pruning much more difficult. Vines will grow into it, tendrils will attach to it, you'll have a difficult time removing them, sooner or later you'll feel like giving up...which is probably what the previous owner did. If it were mine, I'd get rid of everything growing in that fence. Then I'd build a proper trellis and plant new vines.
A proper trellis would be constructed of a single-wire trellis. The end posts should be sturdy and braced to allow the wire to be tightly strung without bowing or sagging. If you leave the fence, construct the trellis far enough away from the fence line to prevent the vines from growing into it.
But, if you decide to go ahead with the farm fence as a vine support, start by cutting all the vines off that stick out from the sides of the fence. Then cut off all the vines at the top of the fence. (Shave it both sides and on top.) This will allow you to see what you're doing.
Next, see if you can find the oldest grape vine trunks. Ideally the original vines should have been planted 20' apart, but there's no telling. If the oldest grape vine trunks are healthy and are spaced reasonably far apart, mark them somehow (colored plastic ribbon). See if you can identify two lateral vines at the tops of the trunks inclined to opposite directions along the fence to use as horizontal arms. Mark them, too, and try not to remove them. After that, remove everything else. That procedure should give you something approaching the T-shape you want. Take whatever is left of the lateral vines (soon-to-be arms) and train them horizontally at the top of the fence, going in opposite directions. Bear in mind that whatever errant vines and roots that remain in the ground will try to sprout next spring, so you'll have to stay on top of that situation.
If you think you've cut off too much for the health of the vines, don't worry about it. Even if you cut them all back to ground level, they'll sprout next spring.
John J Marshall
John also blogs at goGardenNow.blogspot.com.