It is best to transplant a grape vine in the spring after danger of frost has passed in your area. Prepare the new area by soaking with water for several days. Prepare the new hole before you dig up the grapevine. A hole 2 feet in diameter is a good size. Dig to a depth of 2 feet or more. Fill the bottom half of the hole with compost or other organic matter.
Prune the wood on the plant back to within two feet of the base of the plant, cutting the vine just on the outside of a stem node. Dig around the plant a foot to a foot and a half out from the base of the plant, depending upon the size of the plant. Lift the plant and transport it to the new location. Position it in the new hole at the same depth as it was in the original location and fill in around the plant with more compost and garden soil. Water in, adding a solution of Vitamin B1 (available at garden centers) to promote good root growth. Water every day until new growth is established.