Growing Grapes

Basic grape-growing guidelines

Grapes

If you've been thinking about adding grapes to your garden, consider a Concord, Flame Seedless, or Thompson Seedless or one of the many varieties that are never available in the local markets. Grapes are wonderful fresh, dried, and juiced. If cultivated, they can provide plenty of good eating and drinking year around. In addition to their edible qualities, grape leaves and vines are useful in crafts such as wreaths.

Cultivation in home gardens

Grapes like heat and most of the sweetest grapes tend to like plenty of sun and warm temperatures. Most of the continental US is in the grape belt between 30 - 50˚ N. latitude. Cool season plants produce less sugar and are higher in acid. Most areas can grow grapes but check with your County Extension service for tips on the healthiest, most productive varieties for your region, then research detailed cultivation types specific to that variety for the most reliable performance.

Depending on your purpose (i.e., eating, drying, or making juice or wine), climate, and cultivation, a single plant can produce as much as 25-30 pounds of fruit. To get the most from your plants, plant vines where they will get a good southern exposure. The optimum placement is in full sun oriented on a North-South axis. This provides the optimum amount of light and heat.

The growing season is about 150–180 days for standard varieties, though short and long season types are available. The key to production is to select a variety that matures during your growing season ... the earlier the better.

Grapes like deep, well-drained loam soils. Soils that are either too clay-ey or too sandy tend to retain too much water or drain too quickly, so amending the soil to maintain even moisture is important. They also like somewhat acid soils with a pH of between 5 and 5.5. Mulch with fir or pine needles to eliminate weed problems and maintain the pH.

Plant spacing should be about 5–8 feet apart in rows with 8–12 feet between rows. In home gardens, if you plant a sod walkway between rows and fertilize or compost the grass, you will probably not need to add extra fertilizer for the grapes which have far reaching root systems that are capable of harvesting nutrients from some distance.

Propagation

A range of grape varieties are available in containers at nurseries.

Alternately, you can take cuttings without much difficulty in the late winter or early spring during pruning. Select a healthy cane about the diameter of a pencil. Cut the cane straight across below a set of nodes and remove from the plant. Make a second cut at an angle above the third set of nodes. Apply a little rooting hormone to the end with the straight cut, then plant almost up to the middle set of nodes in growing medium. (The cuts help you remember which end is the planting end because it isn't always obvious from the direction of the nodes.) Stake the cutting with an old broomstick or other sturdy support. As the plant grows tie the cane loosely to support it. Tie to the trellis wires as it achieves the height.

Young grape plants like humid conditions and can be put outside if the temperatures are above freezing. Keep them out of direct sunlight until they are acclimated ... usually a week or two.

Pruning

Pruning grapes is important to ensure large bunches of good sized grapes. Though the plants will grow without pruning, you'll notice fewer, smaller bunches over several seasons.

Because grapes are a vine, it's important to give them some structure. You can train them over an arbor, trellis, or along wires. The wire trellis systems used by vintners have sturdy 4x4 wood posts with tightly stretched 9–12 gauge wire running from post to post. Wire vise clamps can be used to secure the wires.

Though there are different pruning systems for grapes, we use the 4-cane Kniffen method. It's fairly straight forward, so it's easy to maintain your grapes if the varieties are hardy and need no winter protection.

Because grapes produce fruit on year-old canes, you'll want to select four young canes to keep (two per side). The canes should be shiny, with a smooth tight brown bark. Canes that are two years old show cracking and peeling and will be removed. Select canes that are the diameter of a pencil or a bit more if possible, one on each side of the plant at a distance of about 36 and 60 inches from the ground. Use bright yarn or tags to mark the canes you want to keep.

Each cane should have well spaced nodes with no more than 10–20 buds per cane. Clip the canes if necessary. Generally, as yield increases, quality decreases so pruning in the early spring or late winter is vital as well as cluster thinning during the growing season if you have a more fruitful variety.

Leave a dozen short renewal spurs close to the main trunk on both sides of the plant at both the first and second wire levels. These will develop into next year's canes.

Pruning should be done early in the spring or late winter. Depending on where you live and your growing season, it could be from January to March. It's best to prune before the sap starts to run, however. Pruning a little too late means that you could leave exposed cuts that will drip profusely and that could attract pests.

Problems

Planting clean, disease-resistant varieties is often useful, especially if you want to avoid using chemical controls.

Birds are often a nuisance with many berries and fruits. Grapes are no exception. Netting to prevent birds from getting to the grapes or flash tape that flutters in the breeze are both effective ways to deter them.

The most deleterious problems for grapes are caused by fungi. Powdery mildew is the bane of gardeners around the world, so control is achieved by plenty of sun, clipping leaves during the growing season to encourage air flow, and good sanitation practices. Other notable fungi problems include black rot and downy mildew, both of which can be controlled by removing and destroying infected fruit, leaves, and vines.


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