Grapevines do best when pruned each year in January or February. If your grapevine has grown wild for several years, it may be producing less fruit and overtaking its planting area. It is highly beneficial for the production of fruit and the overall health of the plant to heavily prune back old grapevines. Fruit is produced only by new wood, so it crucial to encourage new growth each year. Don't be afraid to cut back most of the vines, as this will rejuvenate an old plant.
Prune all vines. Cut back all shoots, including thick woody growth, to the base of the grapevine. Leave a one- to two-foot-tall stump. Use a hand saw for the thickest vines.
Place a trellis around the grapevine. If your old grapevine used a trellis, check it for stability and re-anchor it into the ground. A four-foot-tall trellis is ideal for easy management of the fruit and plant.
Allow the grapevine to grow unchecked. Give your old grapevine about one year to grow without pruning. By the end of the year, it should have used its established root system and produced dozens of new shoots with full, hardy leaves.
Prune again inthe following January or February. Choose the strongest new shoot and tie it to the top of the trellis. Cut back all other shoots to the base of the plant.
Encourage the growth of the tied shoot. Allow new shoots to grow from it and tie vines along the trellis as needed. After four or five shoots sprout, cut back all other growth from the plant to encourage blooming and fruiting on only the strongest shoots.
Prune buds. As the plant grows, it will sprout buds on the shoots tied to the trellis. The flowers will eventually produce fruit. Cut off weak buds, leaving only the biggest and strongest to produce fruit.
Prune your grapevine heavily each winter. Encourage the growth of two sturdy trunks from the base of the plant and cut back all other shoots every January or February.