Gardening Basics: Grapes

Grape Essentials
By: National Gardening editors
Planning
• Choose a variety that is recommended for your climate. Grapes require a long, frost-free growing season.
• Grapes start to bear 2 years after 1-year-old vines are planted. Established vines will yield up to 15 pounds of grapes per year, 30 to 40 pounds from a muscadine.
• Plant grapes in the spring.
Preparation
• Select a site with deep, well-drained, loose soil in full sun.
• Set up a trellis system before planting.
Planting
• Space vines 6 to 10 feet apart (16 feet for muscadines).
• For each vine, dig a planting hole 12 inches deep and 12 inches wide. Fill with 4 inches of topsoil. Trim off broken roots and set the vine into the hole slightly deeper than it grew in the nursery.
• Cover the roots with 6 inches of soil and tamp down. Fill with the remaining soil, but don't tamp this down.
Care
• Prune the top back to two or three buds at planting time and follow the first-year training steps.
• Prune annually when the vines are dormant according to the training system you select.
• Do not fertilize unless the soil is very poor or the plants show poor foliage color or signs of nutrient deficiencies.
• Cultivate shallowly around the base of plants to control weeds.
• Drape netting over vines to prevent birds from destroying your harvest.
• See our article Fruit Pests and Diseases for controls of common grape pests such as aphid, scale, anthracnose, and black rot.
Harvesting
• Grapes will only ripen on the vine. As they ripen, the sugar content rises to about 20 percent.
• Harvest table grapes when the flavor is right; harvest wine grapes when they reach the appropriate sugar content.
Planting Grapes
By: National Gardening editors
The fall before you plant, mark the location for your vines. Get rid of all weeds, especially perennial ones, as your vines can easily survive 30 years or more in the same location. Grapes don't require superior soil, but good drainage is a must. Although you won't start training the vines until the second year, set up the trellis system before spring planting so you don't damage the roots later.
Planting
In the spring, work the soil again and plant the vines 6 to 10 feet apart. (Double this spacing for muscadines.) For each vine, dig a hole 12 inches deep and 12 inches wide to accommodate the roots. Shovel in a 4-inch layer of topsoil. Then prune the top of your grapevine back to two or three buds and trim off any broken roots or roots too long to fit into the hole without crowding. Set the vine into the hole, slightly deeper than it was grown in the nursery, and spread its roots. Cover the roots with 6 inches of topsoil, keeping the buds above the soil line. Tamp down the soil, then fill the remainder of the hole with topsoil but don't tamp it down. Water the new plants well. Although grapevines are known to be drought tolerant, they need plenty of water right after planting so roots can get established.
Photography by NationalGardening.com

Care & Harvesting of Grapes
By: National Gardening editors
Grapes should be pruned yearly because fruits only form on buds that arise from the previous season's growth. There are various methods of training grapevines. Your preferences, space limitations, and the variety of grape you are growing will determine your trellis system. Prune vines when they are dormant; in most of the country, that means very early spring, before any green shoots appear. Muscadines in the Deep South can be pruned any time after the first fall frost.

Fertilizing

Unless your soil is very poor, grapes, which are very deeply rooted, don't require much fertilization. Where fertility is low, a soil test will determine whether you should add phosphorus or potassium. For all soils, fertilize lightly the second year. Apply no more than 1/4 pound of 10-10-10 fertilizer in a circle up to 4 feet away from each vine. In following years when the vines are established, apply about a pound up to 8 feet away from the base if growth was slow or foliage color poor the previous season. Apply it only when the buds start to swell in the spring; later fertilizing may cause extensive growth in late summer, making the plant more vulnerable to winter injury.

Grape Checklist

While grapevines can survive some neglect, they need regular attention to reach maximum yields:

1) Prune carefully. Leaving too much growth causes far more problems than

overpruning.

2) Cultivate shallowly around the base of your plant while it's young to avoid damaging roots near the surface.

3) Fertilize lightly. Unless the soil is particularly poor, grapevines need little feeding. Grape growers encounter a few common problems. For example, if you plant a seedless variety, you may find that your grapes are smaller than those in supermarkets. Grape seeds produce a plant hormone that causes the berries to increase in size. Seedless varieties are missing this hormone and thus produce smaller grapes. If you want larger grapes, keep more buds at pruning and thin out one cluster of every three just before spring bloom. If your grapes are of mature size but fail to ripen on the vine in the (all, the leaves may be shading the grapes, which inhibits ripening. Try pinching foliage-bearing side shoots back to one leaf, which will bring more sunlight and warmth to the clusters.

Grape Pests

Your first planting of grapes may escape insect or disease attacks for a while, but eventually some trouble usually arrives. In humid areas, mildew diseases can be a problem; European grapes are very susceptible to downy mildew, for example. Black rot, caused by a fungus, develops in warm, moist climates of Eastern states. Anthracnose, another fungus disease, flourishes in wet spring weather. Japanese beetles, aphids, and mites are common garden insects that you may find. The grape berry moth is a pest in central and eastern regions. Larvae of the moth feed on buds, blossoms, and berries, tying berries together with silken threads as they feed. Two generations usually occur. Clean up grape leaves in the fall to reduce the number of overwintering pests. The following spring, cultivate around plants to turn up overwintered pupae. The grape phylloxera is a pest common in California, where it attacks roots by sucking juices from them and creating galls, and in the East, where it attacks leaves as well as roots. Galls about the size of peas form on leaf undersides. American varieties are resistant, but other types are not. No chemical controls exist; if you have a severe problem, grow American types or European varieties with resistant American rootstocks.

Harvesting

Grapes do not ripen off the vine, so pick them when they are completely ripe. Use a sharp knife or small pruner to cut the bunches. Bees and wasps may occasionally light on the grapes to feast on some sweet juice, so watch for them.
Grape Pruning: Three Systems
By: National Gardening editors
Grapes must be pruned every year to keep producing because once a cane has fruited, it don't fruit again. Fruits form only on buds that arise from the previous season's growth. Which pruning method you choose depends on the type of grape and variety you have and which seems convenient and efficient to you. For American grapes, the most widespread system is the Four-Arm Kniffen System. For the vigorous muscadine grapes grown in the South, a two-arm version of-the Kniffen System prevents excessive leaf shade.

European wine grapes are generally trained to have two permanent arms and are spur pruned. If you have only a few vines and don't want to put up a wire trellis, you can head-train European grapes instead. .

Pruning is done once a year-after the coldest part of the winter. Be sure to cut back to firm, live wood; the tips are often killed back. Muscadines are usually pruned after the first severe frost in the fall

Training the Vine

The first few years are the same for the basic systems, the goal being to produce a strong root system and trunk. Here are the steps:

1.When planting, cut the vine back to two or three buds. It's a good idea to place trellis stakes or posts by the vine at this time; the wire can be put up later.

2.Early in the first summer, pick out the strongest growing cane and let that one grow. As it gets taller, let several side shoots develop off the main one where you intend to place horizontal supports.

3. The following winter or early spring, prune back all canes as shown. Leave three buds on each of two or four lateral spurs (depending on how many arms you want). Put up wire supports.

4. The second summer, tie the side shoots to the wires as they grow. Remove flower clusters - you don't want the vine to fruit yet. Also remove shoots from all buds except those on the spurs.

Four-Arm Kniffen System

Second Winter

Choose four healthy, well-spaced arms to train on the wire for fruit production. If they are very long, trim back to ten buds. Choose four more canes for

renewal spurs; cut these back to two buds. Remove all other canes. The following summer, the buds on the fruiting canes will grow into long shoots, each bearing two to three bunches of grapes. The buds on the renewal spurs will also produce shoots; if they are vigorous, let them fruit. If not, remove their fruiting clusters.

Third Winter

Remove the canes that fruited and choose one replacement from each renewal spur to tie to the wires. Trim to ten buds. Cut back another four canes to form renewal spurs. Your vine should now look approximately as it did a year ago. Repeat each year.

Spur Pruning: Two-Arm

In this system you develop two permanent arms with spurs that produce fruiting wood each year.

Second Winter

Remove all canes except the best two; tie these to the support wire. The next summer each bud along the arm will send out a fruiting shoot. Weave these in and out of the upper wires.

Third Winter

Check the horizontal branches for the strongest vertical shoots and cut each of these back to two buds. These wilt be the fruiting spurs. Space them about 6 to 10 inches apart. Every bud you leave on the spurs will produce a fruiting shoot the following year. Each year, repeat the process.

Spur Pruning: Head-Trained

For this system, the vine will need only a strong, vertical, 4-foot post for support.

1. Allow the vine to grow to the top of the post and cut just above that point. Tie to the post. Remove any branches below. Next year, let four or five branches grow.

2. In the winter, cut each of the branches back to two or three buds. Remove any weak branches and any on tower parts of the trunk. Buds left on spurs will produce fruiting shoots next year. You can allow more branches to develop as the vine matures so there will be more fruiting shoots each year. A mature head-trained vine can have more than seven main branches.
Buying Grapes
By: National Gardening editors
It's a wonder more gardeners don't plant grapevines. Just 2 years after planting, you can be sampling your own grapes; in 3 years, you can be harvesting up to 15 pounds of grapes from each vine - plenty for eating and making jellies, juice, or wine. Two healthy vines are enough for most home growers. Many gardeners who raise everything from Brussels sprouts to plum trees have never tried grapes. Often, it isn't because they don't like them, but because they think grapes are difficult to prune properly. However, many home gardeners know that grapes are easy to grow. After the first year, you

just need to give vines a simple annual pruning to keep them bearing well. There are three major groups of grapes. American grapes (Vitis labrusca) are generally quite winter hardy and grow well in most parts of the United States. European grapes

(Vitis vinifera) grow best in warm, dry areas. Crosses between European- and American-type grapes have produced hybrids that are hardier and can be grown over a greater range. Muscadine grapes (Vitis rotundifolia) are native grapes well adapted to growing conditions in southeastern United States.

Planning for Grapes

Choose grape varieties carefully. American-type grapes such as 'Concord' and 'Catawba' do well in the cool climate of New England, in the Midwest, and in the Northwest. The 'Concord', developed in the 1850s, is still a mainstay in many home gardens; it's vigorous, hardy, and easy to propagate from cuttings. European grapes (usually wine varieties such as 'Zinfandel' or 'Chardonnay') flourish in California where bright, dry summer days and mild winter temperatures provide a favorable environment. Tougher-skinned muscadine grapes do best in the Deep South.

Some of the new hybrid crosses between European and American types, such as the 'Baco Noir' and 'Seibel' varieties, are hardy and have extended the range in which wine grapes can be grown. Vineyards in New York State, where winter temperatures drop well below zero, produce high quality wines.

Hardy Grapes

Over the years plant breeders have introduced earlier-ripening and more winter-hardy grapes. 'Swenson Red', for example, produces delicious medium to large red table grapes and is winter hardy to -25F. Most grapes are self-fertile, but check to be sure when you place your order. A few will need pollinizing plants. Muscadines come in self-fertile and self-sterile lines. The best fruits are from the self-sterile vines; to assure pollination you have to grow a pollinizing vine, too. Whether a variety is from a self-fertile line or not should be noted in the mail-order catalog or at the nursery. Many garden centers sell grape plants in containers (in 8-inch pots, for example). There's usually a thin, 8- to 10 inch-tall stem that will develop over the years into a sturdy trunk. Vines grown in containers are easy to plant because the roots are less stressed in transplanting. Tap the plant out of the container and set the root ball, with as much of its soil as possible, into a prepared hole.

Buying Grapes

Buying container plants locally can be more expensive than ordering from a mail-order company. If you send away, your grapevines will probably arrive bare-root with a moist packing of peat moss or other material to keep the roots from drying out. The stem is usually cut back at planting. There is no advantage to buying a vine older than 1 year. Roots always have to be trimmed back at planting time, and no matter how old the vine is it takes a certain amount of time for the roots to reestablish themselves. Older vines won't necessarily give you earlier fruiting.