By Joan Allen
UConn Home & Garden Education Center
Have you ever thought you would like to try growing grapes at home, but felt like it might be too difficult? With a little preparation, grapes can be successfully grown in the home garden on a trellis or on an arbor. There are many varieties suitable for Connecticut including both wine and table grapes. Mature vines (4-5 + years old) can produce 20 pounds or more of fruit per vine each season. Planting early, midseason and late ripening varieties can extend the harvest season to several weeks. Vines grown and trained on an arbor provide beauty and shade in addition to fruit. Growing grapes successfully requires good site preparation, selection of winter hardy cultivars, annual pruning and fertilization, and management of diseases and insect pests.
Grapes do well on a site with full sun, well-drained soil and good air flow. The best time to plant is early spring as soon as the ground can be worked. Have the support system, whether it is a trellis or an arbor, in place prior to planting. A simple trellis is economical and versatile. Place sturdy wooden posts 24 feet apart and string galvanized wire between them at heights of 3 and 6 feet above the ground. Place vines 8 feet apart on a trellis or 4 feet apart for an arbor. At planting time, prune off broken or dead branches and roots. Prune off all but one vigorous cane from the top growth. Prepare a hole large enough to spread out the roots and place the plants at the same planting depth as in the nursery, usually 2-3” above root level. Do not fertilize at planting time. Keep an area 18-24” around each vine free of weeds by hoeing or using plastic or organic mulch. If the cane does not reach the lowest wire or support, tie it to a stake for the first season.
Fertilize your new grape vines 1-3 weeks after planting with 4 oz. 10-10-10 fertilizer per vine applied 6-12” from the trunk. Water if conditions are dry. In the second season, apply 1 lb. 10-10-10 fertilizer and in subsequent years apply 1-1.5 lbs. Applications may be split between just before bud break and 4 weeks later. For wine grapes, decrease fertilizer to 3 oz. the first year and 0.5 lbs. in subsequent years. Maintain a pH of 5.0 – 5.5 for table grapes and 5.8 – 6.5 for wine grapes. Soil testing is recommended prior to planting and every 2-3 years for lime and fertilizer applications.
Annual dormant season pruning is important for maintaining vine size and form and for optimizing vegetative growth and fruit production. Pruning also improves air flow around the leaves which aids in disease prevention. A popular pruning system for the home garden is the four-arm Kniffen system, shown in the illustration. It consists of a single main trunk with four side branches, extending out from the trunk along the wires. Late in the dormant season (March) of the second year, tie the cane to the top (6 foot) trellis wire and prune it off just above the wire. If the cane does not yet reach the top wire, treat it as a first year cane. Remove all growth except for 4 – 6 buds near each wire. As shoots develop, remove any flower clusters that form. In early spring of the third year, before growth begins, select 4 canes for each of the two wires (total of 8). Tie one cane to each wire in each direction (4 canes). Allow these to bear fruit up to the 6th bud along the arm. Cut the other 4 canes back to a stub bearing 2 buds. When pruning mature vines, remove the fruiting canes from the previous year. Tie one of the 2 canes that grew from the stub to the wire and cut after the 10th bud. Cut the remaining cane to 2 buds for next year’s stub and arm.
To train vines to an arbor, the trunk is allowed to grow longer to provide shade. Short permanent arms are trained so the foliage will cover the arbor. For best results, do an annual renewal pruning.
The best grapes for Connecticut are at least moderately winter hardy. American cultivars (Vitis lambrusca) and French hybrid types (crosses between V. lambrusca and V. vinifera) are recommended. European (Vitis vinifera) grapes are generally less winter hardy. Cultivars can be selected based on grape color, size, flavor, end use, ripening time and vine disease resistance. Some popular table grape varieties include Concord, Lakemont, Reliance, Interlaken, Canadice and Himrod. Wine grape cultivars suggested for Connecticut are Cayuga white, Niagara, Baco noir, and Marechal Foch. A good source for more information on cultivar selection is the fact sheet “Grape Varieties for Connecticut” available online at www.ct.gov/caes (CT Agricultural Experiment Station). Search for fact sheets and select the fruit option.
There are important diseases and insect pests of grapes that need to be managed to produce healthy fruit. The most common diseases are black rot, downy mildew, powdery mildew and botrytis bunch mold or gray rot. Insect pests include grape berry moth, grape cane girdler, grape flea beetle, Japanese beetles, and grape phylloxera. Controls include culture, sanitation, resistance and chemical sprays. A general spray guide is available at the website mentioned above. Cultural methods improve plant vigor and include proper fertilizing, pruning and care practices that minimize stress. Sanitation involves removal of affected or dead plant material by pruning and removing plant litter on the ground.
For more information on growing and caring for grapes or other home and garden topics, contact the UConn Home & Garden Education Center toll free at (877)486-6271 or by email at email@example.com.