Prune muscadine or bunch-type grapevines annually during the winter dormant season. Prune in late January in South Florida, February in Central Florida and by mid-March in Northern Florida--before the dormant buds swell and the new leaves emerge.
Reduce the length of all side branches that dangle off of the four cordons on the trellis system so that only two to four leaf buds remain (this creates a "spur"). Make these cuts on side branches with a hand pruner 1/2 inch above a bud. Discard the branches into a compost pile; consider cutting long vine debris into 18-inch segments for easier handling and faster decomposition.
Remove spurs on each cordon so that they are spaced every 6 to 10 inches. Make pruning cuts to remove the spurs 1/2 inch above their point of attachment to the main horizontal cordons.