Grapevines (Vinis vitifera var.) are hardy, fast-growing climbing plants that can easily be trained to topiary forms as they grow. Because grapevine leaves are large and the plant has an open growing habit, choose large, simple topiary shapes that do not require fine detail better-suited to dense, small-leaf plants. Geometric shapes like globes or pyramid as well as wreath and standards are well-suited to grapevine topiary.
Mix two parts potting medium with one part sand and one part compost. Add water until the mixture is well-saturated.
Place 2 inches of gravel in the bottom of large pot. Fill the pot to within 2 inches of the rim with wet potting medium.
Drill a half-inch hole in the center of the block of 1-inch-thick lumber, using the electric drill and half-inch drill bit. Cut the dowel to desired length plus 6 inches with a hand saw. Paint the dowel if desired. Place the tip of one end of a spool of No. 9 wire in the drilled hole, then insert one end of dowel into the drilled hole, securing the wire.
Scoop out a 6-inch-deep, 5-inch-wide hole in the potting mix, in the center of the pot, with your hands. Stand the dowel and base in the hole. Holding the dowel upright, backfill around the base and dowel with the scooped-aside soil. Press the soil down firmly around the dowel to secure it in its upright position.
Plant the grapevine adjacent to the dowel, 2 inches off the center of the pot, following nursery tag directions for appropriate planting depth for your variety.
Wind the No. 9 wire in a spiral up the dowel, then form the wire into the desired standard shape atop the dowel (wreath, globe, or other form), leaving several inches between each loop of the wire. Cut the necessary length of wire from the spool with wire cutters.
Wrap the grapevine stems through and around the wire. Use bypass pruners to trim side-shoots that cannot easily be incorporated into the shape. Tie the stems to the wire frame with raffia placed 4 inches from the growing tip of each stem.
Place the topiary grapevine in a sunny location. Water weekly, adding water-soluble houseplant fertilizer once a month.
Continue to wrap the grapevine stems to the wire frame as it grows, tying the growing ends of the stems to the wire frame with raffia and trimming off side shoots with the pruners as needed. When the topiary has reached its desired state of fullness, regularly pinch off the growing tips of the stem ends to restrain additional growth.