There are countless varieties of grapes. Table grapes are those grown to eat fresh from the vine, while wine grapes are better used in the production of that beverage. Select plants based on climatic zone as well the desired use. Popular varieties of table grapes include Concord and Red Flame. Popular varieties of wine grapes include zinfandel and chardonnay.
Grape vines should be located in sites with well-drained sandy soil that receive full sun. Work at least 2" of organic soil conditioner into the top 10" of the planting site. Grape vines require a trellis or support system of some kind. As a general rule, each grapevine needs about 4' to 5' of trellis space. It’s wise to position the trellis before planting the grape vines.
Soak the vines in a bucket of water to keep the roots hydrated. Dig a planting hole at the base of the trellis. If planting multiple vines, space the holes 5' to 8' apart. Place the grape vine in the hole and fan out its roots (Image 1). The point on the stem where the roots flare out should be about 1" below the soil line. Backfill with soil until the hole is three-quarters full (Image2). Water well to settle the soil. Finish filling the hole and water again. Add mulch around the vines (Image 3).
To keep your grapes healthy, it is important to prune your crop. The pruning method you use will depend on your climate and the type of grapes you are growing. One method is a training method called a double split trellis system where the vine is trained by splitting it, sending part of the vine to the left and part of the vine to the right.
Proper pruning techniques can make or break the success of a grape vine. After planting, prune the vine back to just one vigorous cane. The following spring, prune all but the most vigorous canes. Carefully tie the remaining canes to the trellis with twine. In future years, continue to keep only the most vigorous canes while pruning older, weaker ones.
Properly irrigating your grapes is essential to a healthy grape crop. Young vines need a fair amount of water, while older vines do not require as much water. To give your plants what they need, a drip irrigation system is best since it keeps the foliage dry, which reduces the likelihood of disease.
Young vines need a fair amount of water while they are getting established. Drip irrigation is the best method since it prevents water from getting on the leaves, which can cause disease. For mature vines, too little water is better than too much water. In late spring, apply a slow-release 10-10-10 fertilizer around the plants but away from the stems.
The first year, thin all the flower clusters that appear on the vines. This focuses the plant’s energy on producing healthy leaves, branches and roots. In following years, thin flower clusters to just one or two per shoot. This provides more room for the remaining clusters to grow to full size.
The best way to tell if your grapes are ripe is by tasting them. Since grapes do not continue to ripen after they are picked, be sure to test your grapes before you harvest. When you are ready to harvest, cut a whole cluster of ripe grapes at one time by using a regular pair of shears with an extra long nose. This will help you reach into the top of the stem of the grape without damaging the cluster.
The best way to tell when table grapes are ready for harvest is by tasting them. Grapes don't ripen after picking, so make sure they're fully ripe before harvesting them. For wine grapes, the use of a refractometer to test the fruit’s sugar content may be necessary. The grapes should have between 18 and 22 percent sugar.