Considerations
Before Planting
Cultivar
Selection
Home gardeners can choose from a wide variety of grape cultivars,
each differing in time of ripening, productivity, vigor, hardiness, and fruit
size, color, and flavor. The majority of the grapes grown commercially on Long
Island are vinifera grapes (Vitis vinifera). Vinifera grapes are the
classic European wine grape. Vinifera varieties include: Chardonnay, Merlot,
Cabernet Sauvignon, Riesling, Thompson Seedless and Gewurztraminer. The vinifera
grapes are more susceptible to winter injury and fungal diseases. Vinifera grapes
require the use of a rootstock and currently 3309 is a recommended rootstock
for Long Island.
American bunch grapes (Vitis labrusca) are the type most widely cultivated in the Northeast. American bunch type varieties include: Concord, Niagara, Delaware, Fredonia and Catawba. The juice and jelly industry is based on American types. They are more tolerant (but not resistant) of fungal diseases.
The French-American hybrid grapes are a cross between Vitis vinifera and Vitis labrusca. French-American varieties include: Seyval, Cayuga (white), Aurore, Ravat, Vidal, Baco Noir, De Chaunac, Marechal Foch (black), Cascade (blue), Chancellor (red). The hybrid grapes ideally have some of the fine wine qualities of the vinifera grapes and some of the disease tolerance of the American varieties. If managed properly, the hybrids can be high yielding and are less susceptible to winter injury in comparison to the vinifera grapes. Hybrid grapes are a good first choice for a home winemaker.
In addition to the three major types of seeded grapes mentioned above, seedless grapes for fresh consumption are also grown throughout the country. Some seedless table grapes to consider are: Concord Seedless. Glenora, Remaily, Canadice, Himrod, Einset, Vanessa, Reliance, and Lakemont. Even though these seedless varieties are less than perfect, their flavor far exceeds that of Thompson and Flame seedless from the West Coast. The cultural practices differ for the seedless grapes in comparison to other types of grapes and can be a challenge to home gardeners. Refer to The Home Fruit Planting, Information Bulletin 156, A Cornell Cooperative Extension Publication for further information on growing seedless grapes.
Purchasing
Vines
Purchase grapevines from a reputable nursery, placing orders
early to ensure that the desired cultivars will be available. Request that the
grapevines arrive in early spring, and plant immediately.
Site
Selection
A favorable climate is essential for successful grape growing.
Specific requirements include a minimum growing season of 150 days; winter temperatures
above -250 F; an area that accumulates more than 2,000 degree days above 500
F; and a site that is exposed to full sunlight, has good air drainage, and is
neither wet nor droughty. Southern slopes or exposures protected by buildings
or windbreaks are preferable to northern slopes and low ground, which tend to
be cooler throughout the growing season and delay ripening of the fruit. Grapes
tolerate a range of soil types and are not as sensitive to extremes in drainage
as other fruit crops. They are, however, most successfully grown on deep, well
drained sandy loam soils.
Early
Care
Planting
Purchased vines should be planted in the spring as soon as the
soil can be worked. Set vines a minimum of 8 feet apart both within and between
rows, digging a hole large enough to spread out roots sufficiently. After trimming
away broken or excessively long roots, lay out the root system in the hole and
cover completely with soil. Planting depth should be the same as in the nursery,
usually about 2 to 3 inches above root level. If using grafted vines, do not
cover the scion. You do not want roots on this portion -- this defeats the purpose
of using a rootstock. Remove all but the best single cane and tie it to a stake
or the bottom wire of a trellis to hold it erect. After several weeks, buds
should begin to grow. When the new shoots are 10 inches long, remove all but
the strongest as well as any other shoots that arise from the trunk. Flower
clusters or side shoots should be removed as the single canes is growing.
Maintenance
Fertilization
Use no fertilizer the first year. In early spring of subsequent
years, before growth begins, spread 10-10-10 around the vines in the following
amounts: second year, 2 ounces; third year, 4 ounces; fourth year, 8 ounces;
fifth year and after, 16 ounces. Commercial grape growers have a soil test and
leaf analysis done every three years to avoid unnecessary nutrient imbalances.
Home gardeners should consider this also. Contact Cornell Cooperative Extension
- Suffolk County for information on soil and leaf analysis.
Pruning
and Training Young Vines
The four-arm
Kniffen system (Figure 1) is the recommended training method for home gardens,
although many other systems can be used. This system uses a trellis made by
stringing two lines of galvanized wire (size 9, 10, or 11) or monofilament between
durable wooden trellis posts set about 24 feet apart. The top wire of the trellis
should be about 6 feet high and the lower, parallel wire about 3 feet high.
During the first year, follow the recommendations given for planting and fertilization. If the cane does not reach the top trellis wire in the first year, allow it to grow as a single cane the following year until it reaches the top wire.
In early spring of the second year, tie the cane to the top trellis wire and cut it off just above the wire. Leave 4 to 6 buds in the vicinity of each wire and remove the rest. As new shoots begin to grow from the remaining buds, remove any flower clusters that form.
In early spring of the third year before growth occurs, select a total of 8 canes (4 for each wire) and remove the rest. One cane should be tied along each wire in each direction. Allow these four arms to fruit up to the sixth bud along the arm. Cut the remaining four canes back to a stub containing two buds.
Pruning
Mature Vines
In early spring, remove the fruiting cane from the previous year.
Tie one of the two canes from the stub to the trellis wire and cut after the
tenth bud. Cut the remaining cane to two buds for next year's stub and arm (Figure
2). In subsequent years, adjust the number of buds on each arm. The presence
of too many buds results in poor fruit quality and vegetative growth; a shortage
of buds reduces the crop.
Grape buds vary greatly in fruitfulness. The most productive buds occur at the top of the trellis where the shoots of the previous season were exposed to the most light. These canes should have an internode diameter of 1/4 inch or more, an internode length of 6 inches, and a chocolate brown bark that is firmly attached to plump wood.
Pruning
Neglected Vines
It is possible to renew old neglected vines by pruning correctly
in stages. In the first year, limit the vine to a few new canes originating
as close to the trunk as possible, and remove all fruit clusters from the new
canes. Do not remove the old cane at this time. Select one vigorous cane originating
from the root or at a low level on the trunk and tie it to the wires of the
trellis to form a new trunk. Treat this sprout as a young vine, training it
to a four-arm Kniffin. Remove the old trunk after one year.
Training
Vines to an Arbor
Grapevines can be grown on arbors to furnish shade as well as
fruit. The same principles of pruning are followed, although the method of training
is modified.
The primary differences between trellis training and training vines to an arbor are in the amount of old wood left, the number of buds retained, and the distribution of the fruiting canes. More fruiting canes and spurs, and consequently more buds, are kept than would be desirable on a vine confined to less space. The trunk is allowed to grow longer to supply shade. Short permanent arms originating from the trunk are trained so the foliage will cover the arbor to the best advantage. For best results, arbor vines should receive annual renewal pruning.
Harvest
Grapes should be harvested
only after they are fully ripe. Unlike many other fruits, the sugar content
does not increase after grapes are picked. Often grapes have good size and color
one week before the sugar content is sufficiently high. After the sugar content
has peaked, the quality of the grape deteriorates rapidly.
Yield depends on the cultivar, climate, and vigor of the vine. In the third year, vines can be expected to produce 5 to 10 pounds of fruit.
If you plan on storing grapes for later use, proper postharvest care is essential for keeping them in edible condition. Grapes in the best condition when picked will last longest. Handle clusters with care and remove any discolored, injured, or undesirable berries. Cool them as soon as they are picked; a refrigerator with the temperature set in the mid-30's (0 F) is preferable to a cellar or other cool place where temperatures fluctuate. Wrap grapes loosely in plastic material to prevent excessive loss of moisture.
The information for this
fact sheet was obtained from: The Home Fruit Planting, Information Bulletin
156, A Cornell Cooperative Extension Publication, by Marcia Eames-Sheavly
and Marvin P. Pritts, 6/95; and Grape Growing For The Home Gardener, by Alice
V. Wise, Viticultural Research Specialist, Cornell Cooperative Extension - Suffolk
County.
3/97
For more information contact: Tom Kowalsick, Extension Educator - Horticulture, CCE - Suffolk County
4/03
