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Grape Growing and Harvest Information

by chuck.mcmullan
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Grapes are a hardy perennial, well adapted to growing in a wide variety of climate conditions. Although grapes can be a challenge to grow, the time invested now will ensure a bountiful harvest for many years to come. A single grapevine will produce up to twenty pounds of grapes per year and a properly maintained grape plant could last up to forty years!

Where to Grow Grapes

All grapes love full sun. They also like good drainage and air circulation, making a southern facing hillside an ideal location for growing grapes. Grapes require a large area around the base of the plant, at least 8 feet, so be sure to pick a spot with plenty of room for the plants to spread out as well as a place where they can stay for a long long time.

Recommended Varieties of Grapes

Grapes can be grown just about anywhere, but they do differ greatly in their tolerance to disease, pests, and cold weather. Since grapevines are naturally adaptable, many successful backyard vineyards have been established in nontraditional growing areas. The important thing is to select a variety that does well in your specific conditions. The grapes should have enough time to mature within the duration of the growing season for your area. There are early and late varieties that vary quite a bit in the length of season they require to produce fully mature grapes. Ask your local nursery which varieties are best for your area.

Another important consideration is how the grapes will be consumed. Table grapes are intended to be eaten, and wine grapes are intended to make wine. You might be disappointed if you unknowingly substitute one for the other thinking they are all the same. Most table grapes cannot be used to make wine because they don’t have a high enough sugar or acid content, whereas, most wine grapes are small and seedy, not great for eating. Some table grapes are best eaten right off the vine, some are best preserved in jellies and jams, and others are best dried into raisins.

In the eastern United States, local nurseries commonly carry Concord varieties. Concord varieties tend to have a more drooping growth habit and need to be trained high. In the western United States, local nurseries commonly carry European Vinifera varieties. Vinifera varieties tend to have a more upward growth habit and need to be trained low.

Popular table grapes include Concord, Perlette, and Ruby varieties.

Popular wine grapes include Chardonnay and Muscadine varieties.

Temperature
Germination70F
Soil and Water
FertilizerWork in compost before planting in early spring. Fertilizer can be used sparingly the first year or two to encourage growth of your news plants. Fertilizer encourages the growth of wood and green leaves, which takes away from fruit production, and is not recommended for mature plants.
Grapes can grow in any soil type with good drainage, air circulation and full sun. They are a very deep rooted plant and therefore do not require frequent watering.
pH6.0 - 7.2
WaterHeavily and deeply, but infrequently
Measurements
Planting DepthCover root ball
Root Depth> 6'
Height4 - 10'
Width6 - 10'
Space between plants
In Rows8'
Space Between Rows8-10'
Harvest
Grapes are full colored long before they are ripe and do not continue to ripen once they are picked. Taste the grapes and pick them when they are at desired sweetness.
Companions
CompanionsClover, Geraniums, Hyssop, Oregano, Basil, Beans, Peas, Blackberries, Chives
IncompatiblesCabbage, Radish

Soil for Planting Grapes

Grapes are not particular about soil composition, planting depth, or fertilization. They will thrive in sandy or rocky soil but do require good drainage and air circulation. Excessively wet or dry soil should be avoided. Frost-free micro-climates are preferred for those growers in the colder growing regions that might experience some frost on the edges of the growing season. Grape plants are sensitive to frost. Adequate soil preparation is essential since grapes have deep roots and are very long-lived plants. It’s always best practice to remove weeds and work compost into the soil before planting. You will want to cultivate a large area around the base of the plants (at least 8 feet in diameter). The roots of a single grapevine can spread out three to six feet from the base of the plant, and penetrate deep into the soil.

Planting Grapes

When to start seeds –

While it is possible to grow grapes from seed, it can be difficult. Grape plants are typically purchased as a plant, made from cuttings or grafted onto a suitable rootstock. Grape seeds must undergo stratification or undergo a simulated winter period in order to germinate. Seeds can be placed in a moist paper towel inside a plastic bag and stored in the refrigerator for at least 2-3 months. After removing your seeds from the refrigerator, plant them in peat pots, place them in the sun, and keep them at around 70 degrees during the day (spring weather). Once the seed has germinated the seedling can be planted outside once all danger of frost is gone in your area.

When to start plants –

When purchasing plants, choose plants that aren’t diseased, are well rooted, and at least one year old. It is important not to let the root ball dry out before planting. Plant grapes in early spring, as soon as the soil can be worked, and the danger of frost has passed for your area.

How to plant Grapes –

The first and most important step is to select a location for your backyard vineyard. Choose a place that gets full sun and has good drainage and has plenty of room for your grapes vines to spread out. You also need to consider how you plan to train your grapes, for example, it may be practical to use an existing trellis or fence line to support your vines. Be sure to till the soil well and add some sand or peat moss if you have a lot of clay in your soil to ensure good drainage. Dig a hole deep enough to comfortably place the root ball and cover the root ball completely with dirt.

The spacing of grape plants depends on how vigorous the particular variety of grapes are. There are grapes that grow with a so-called high vigor and some grow with a low vigor, which basically refers to the rate at which the canopy grows. If high vigor vines are planted too close they will run into each other and create a tangled mess. Low vigor vines planted too far apart will create gaps between plants and waste space in your backyard vineyard. Be sure to look up planting instructions for your specific variety. Generally speaking, grapevines should be planted approximately eight feet apart with eight to ten feet between rows for optimum productivity.

Storage Requirements
Fresh grapes maintain good quality for 2-3 days in the refrigerator in a covered container or plastic bag. Wash just before eating or preserving.
Fresh
TemperatureHumidityStorage Life
32 - 36F90 - 100%up to 2 weeks
Preserved
MethodTasteShelf Life
CannedGood12+ months
FrozenExcellent8 - 12 months
Dried (Raisins)Fair 9 - 18 months

Cultivating Grapes

Keeping your grapevines pruned each year will increase the quality and quantity of grapes produced as well as the overall health of the vine. Pruning encourages new growth which is very important since grapevines only produce fruit on new growth. Maximum exposure to the sun will give your grapes optimal conditions for ripening. Overgrown vines become shaded by their own leaves and are much more susceptible to diseases and pests. For maximum production, remove 75-90% of the previous year’s growth in late winter to have the proper amount of year-old cane ready for production in the following spring. Too much pruning results in an abundance of foliage, but very little fruit. Too little pruning results in large yields of poor quality fruit. The idea is to balance the vine to provide enough green leafy growth to support the fruit crop and allow the correct mixture of sun and shade to ensure good grapes. The pruning method will depend on the variety of grape and it’s growth habits.

A few terms describing the anatomy of the grapevine will be helpful to describe how to prune them. The main support for all vines is the trunk. Growing laterally from the trunk are “arms”. There are commonly two arms, but sometimes several more. Coming from the arms are “canes”. Located on the canes are “buds”, these are little nodes that give rise to the new wood on which fruit develops. If you leave too many buds there will be little or no fruit and lots of bushy vine. If the cane is pruned quite short, to two or so buds, it is called a “spur”. Do not count buds closer than ¼ inch from the base of the cane. Generally speaking, grapes should be pruned in the winter, but preferably after the most severe winter weather. March is generally a good time of year for pruning in most locations.

Grapes growing on an established grapevine

When starting vines put the vine in the ground with a post and let it grow until it’s next dormant period. This allows the vine to settle in and establish a sound root system. During the next dormant period select the dominant cane and remove all the other canes at their base. Prune this dominant cane back leaving two or three buds on it. In the growth period of the second year, when the dominant cane bud shoots have grown about 12 inches, select the dominant shoot (cane) from these and cut all others off. This will become the vine’s trunk. In order to develop the lateral arms, pinch the tip off the dominant cane about six inches above the level you want the arms to finally be. When sturdy lateral canes (to become the arms) have developed, remove all other buds and canes. In the vine’s third year the training period is largely complete. It is now in its permanent form and ready for production. It is important to remove all fruit from young vines early each summer when the vines are in their formative years. Fruit-bearing before the vines are sturdy and mature may reduce its productivity for many years to come.

Once the plant is established, there are two common methods used to prune the canopy. Cane pruning involves looking at the arms and selectively cutting out canes leaving about six inches between each. Each cane should ideally have about 10 to 15 buds left. The alternate canes are then pruned so that they only have two buds left, resulting in an alternating pattern of one short cane and one long cane. The short spurs will send out canes for next year’s crop. All varieties of grapes can be cane pruned, but Thompson Seedless grapes must be. This is because the first three to six buds on Thompson Seedless grape canes are virtually fruitless. Spur pruning is less complicated in that all selected canes are pruned to two or three buds. Check the recommendations for your particular variety, or experiment with both methods to find out what works best for you and your grapes.

Grapevines do not perform well left to grow along the ground and they will need some sort of support since they are not strong enough to support themselves. A trellis can be made from a wide variety of materials, and may even utilize some existing structure, such as a fence if preferred. For larger crops, a wire based trellis system is usually fabricated. It is important to make the trellis strong enough to support the vines as well as a full crop of grapes in high winds and other weather conditions. Trellis systems vary based on the climate with taller ones in warmer areas, and shorter ones in cooler areas. They basically consist of a strong post placed in intervals of approximately 20 feet with 12 gauge galvanized steel wire along the post. The wire is run along the posts and secured under tension to properly support the grapes.

Harvesting Grapes

Grapes change color long before they are ripe. To best judge when to harvest your grapes, taste them! Grapes will not continue to ripen after they are picked. The longer they are on the vine, the sweeter they become. If you intend to make wine with your grapes, you may want to purchase a refractometer to determine the sugar content of the grapes. A refractometer is a handheld device that measures in index of refraction of liquids. A juice sample is placed on the prism, and the device measures how the light is reflected; which corresponds directly to the sugar content of the sample. Wine grapes usually need a sugar content of 22-24% or more. Grapes are full-colored long before they are ripe and do not continue to ripen once they are picked. Taste the grapes and pick them when they are at the desired sweetness.

Grape Pests

Keeping your plants properly pruned and cleaning up grape leaves in the fall will help to decrease the number of overwintering pests. In the spring, cultivate around the base of each plant to turn up any overwintered pupae. Planting coriander or borage in your yard can help attract bees to your grapevines. Planting chives and Nasturtiums will discourage Aphids.

  • Japanese Beetles can reduce productivity. Geraniums planted within or around your backyard vineyard will help to deter Japanese Beetles.
  • Rose Chafer are large beetles that eat the grapes.
  • Grape Berry Moths lay eggs directly on the grapes. The larvae will drill into the berries, leaving small holes and webbing in between the berries.

Deer and birds can also devastate your grapevines. Use of tubular wire cages can help to deter deer as well as human, dog or coyote scent. Netting can be used to protect your plants from birds as well as aluminum pie plates and artificial hawks, owls or snakes. If using netting to protect plants from birds, be sure to remove before winter to avoid ice forming on the netting and damaging the plants.

Grape Diseases

  • Mildew and fungus diseases are common among grape growers in humid areas. Symptoms of disease include discoloration of leaves, film on leaves, lesions on leaves or decay of berries. Seedless varieties are usually the most disease resistant.
  • Powdery Mildew – white, powder-like substance on the leaves
  • Downy Mildew – light green to yellow spots on leaves
  • Black Rot – brown circular lesions on leaves

Diseases can vary depending on what region you live in. Be sure to research diseases that are common in your particular growing area.

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