Before you start growing grape vines, it is imperative to build a trellis system to support your vines.
Constructing a trellis
The trellis should be constructed with heavy treated posts. Light-weight trellises will give you nothing but trouble later on, so spend the time and money to build it the right way the first time.
End posts should be solid because they will carry the bulk of the weight. Treaded wooden posts, measuring 6 to 8 inches in diameter or a heavy gauge 4-inch metal pipe will work. Brace the end posts using a deadman, screw anchor, or H-end post brace.
A 9-foot end post should be set 3 feet into the ground with 6 feet sticking up to support the wires. Intermediate posts are set every 50 to 80 feet along the row to give extra support. Treated landscape timbers work well as intermediate posts. A 2 x 2 treated stake or metal T-post is placed at the location of each grape vine (every 8 feet).
High tension galvanized wire, size 9 to 13 gauge, is usually recommended. You will need 2 wires to support the grape vines and an optional wire to support the drip irrigation line. The irrigation wire should be hung at a height of 18 to 24 inches. The other two wires are hung at 4 feet and 6 feet. Once you have completed this step you may plant your vines. A similar structure can be built for muscadines, but the grapes should be planted 20 to 22 feet apart.
Training and Pruning
Vines should be purchased and planted during the dormant season (December through February). It is best to have the vineyard trellis already constructed and ready to go before planting the vines. Trim off any dead wood and damaged or diseased roots. Plant the vines in existing soil in a location with good drainage.
After planting, trim the vine back to 2 good, healthy buds and tie it to the stake. As the vines grow, the strongest shoot can be trained up the stake to become the main trunk.
At this point you must decide which training system you plan to use. There are two main systems in use today: the cordon system and the cane system.
As soon as the main trunk reaches the wire located at 4 feet above the ground, the tip should be pinched out to encourage branching. Remove any suckers that develop along the trunk and select two lateral shoots to train down the wire. These lateral shoots will become the permanent scaffolds for the life of the vine.
By the end of the fruit growing season, the main framework should be fairly developed. The lateral branches should be attached to the wire and trimmed back until they are 4 feet long. Any branches that may have developed on the laterals should be removed at this time.
During the second growing season, select only upright cordons, allow them to grow until the new growth can be attached to the top wire of the trellis. Any fruit that develops during the second season should be removed.
By the end of the second season, you should have completed the basic structure of the cordon system. Grapes produce their fruiting canes (cordons) from the healthy buds on last year’s wood. Each cane will produce about two clusters of grapes and an average healthy vine will only support 60 to 90 bunches. This means that each year, only 30 to 45 healthy buds should remain after pruning.
With the cordon system, you should prune the vines each year, usually in December. Select 15 to 22 upright cordons and prune them back to 2 buds. The grape spurs should be spaced 4 to 6 inches apart along the lateral branches. These grape spurs will support the next season’s fruiting canes. When you have finished pruning the vine, all that will remain in the main trunk, two 4-foot-long lateral branches, and 15 to 22 grape spurs with 2 buds each. Now the number of spurs will vary from year to year, based on the rate of growth. A very vigorous vine producing more than 4 feet of new growth can have a few more buds, while a vine producing less than 2 feet of growth should have less buds remaining after pruning. This same pruning system will be used throughout the life of the vine.
The cordon system is the most common training system in use today, but some varieties produce better using the cane system. Begin the same way with the cane system as you would with the cordon system. When the vine reaches the bottom wire, it should be tipped to encourage branching. Select two lateral branches and train them down the wires. Attach the vines to the trellis with vineyard ties every foot or so. Tie a third upright shoot to the stake and train it toward the top wire. If it gets to the top wire, it too should be tipped and the 2 laterals should be trained down the top wire.
By the end of the first growing season, you will ideally have a main trunk to the top wire and 2 to 4 lateral branches. Everything else should be removed. The lateral branches can be cut back, leaving 12- to 18-inch stubs. Remember do not let the vines produce the second season.
The second year, allow the vines to grow but not to bear. In December, once the vine is dormant, select 4 strong arms or laterals and attach them to the wires. Near the main trunk, find a renewal cane and prune it back to 2 buds. These spurs will develop into replacement cane for the next season’s crop. The 4 laterals should be pruned back, leaving a total of 30 to 45 buds.
Once you have finished pruning the grapes, all that will remain is a main trunk, 4 renewal spurs, and 4 lateral canes with a total of 30 to 45 buds. As with the cordon system, the rate of growth determines how many buds remain after pruning. Each year, you should remove all but 4 of the new canes and 4 renewal spurs.