Although you can take cuttings from a Scuppernong grape vine almost anytime, taking cuttings in the growing season allows all fall and winter for the branches to root. Even trimmings left on the ground for a couple of days will produce roots if you provide them with a site conducive site for growing. The cold of winter will kill the young roots if they have not had enough time to grow.
When you take the Scuppernong cuttings, select sections with three or four buds per 8 inches. Use younger, green wood instead of the brown, hard branches. You can coax the older branches into rooting, but they will take longer and then slow growth will stunt the leaves in comparison with the leaves from younger wood.
Trim off the thinner wood at the ends of the Scuppernong vines and use the wood that is close to the thickness of a pencil. The roots and leaves that the pencil-sized branch produces will be larger and harder than trying to grow thin cuttings. Pencil-sized cuttings will have more buds per section than the thinner sections as well, creating more sites for rooting.
Bury the Scuppernong cuttings, leaving only the top one or two growth buds or leaves visible. The type of potting soil is typically a peat and sand mixture but other mixtures will work as long as they are well draining -- grapes do not like wet roots. Allow a couple of months for the cuttings to root in a warm place or in the shade of your yard outside before the onset of winter. If you are expecting a cold winter, protect the cuttings in a garage or basement. In the spring, transplant the rooted vines to a permanent position.