Wild grape vines are not much different than cultivated grapevines, except that they probably sprouted up from a seed instead of being planted. Some wild grapes are very tart or even bitter, but with some pruning and care, the same wild grapevine can be cultivated to produce much larger and sweeter grapes than if left to grow wild.
Things You'll Need
Support posts or stakes
Clear out the area around the grapevine trunk, removing any shrubs and weeds. Since grapes need plenty of sun to grow, you will often see the vines stretching high into the canopy of trees as they reach for the sunlight. If you are going to cut back a wild vine to prune and cultivate, make sure it is not growing under trees or it will not get enough sunlight. Mow down any competing weeds within at least 3 feet of the base of the vine and then pull out weeds within 1 foot.
Cut off everything on the vine above 6 feet. The best time to do this is in the early spring around March, before vigorous growing has started, but grapes are extremely hardy and will rebound from severe pruning even if done later in the year. Cut the vine back every year to the 6-foot mark and it will thicken to form a sturdy trunk after several years of pruning.
Prune any side growth all the way back to the main trunk, leaving three or four evenly and oppositely spaced side branches. On these branches--called laterals--prune growth to just after the third growing bud. This will force all the energy in the vine into just a few branches and the fruit growing on them. Make sure your cuts are at a 45-degree angle and face downward towards the center branch.
Secure a support pole, such as 7-foot steel plant stake, into the ground 6 inches out from the base of the vine. Or, construct a trellis from 14-gauge wire stretched between 6-inch-thick and 6-foot-tall side posts, placed at least 6 feet apart. Place the wires through holes drilled every 18 inches to tie on the side branches. The posts will need to be buried about 3 feet deep to withstand the weight of the wires and grapevines.
Wire the vine to the support. Wrap the wire loosely so that it does not cut into the bark of the vine, which would damage and possibly kill it.
Prune and rewire the vine every spring.