Table Grape Varieties for Michigan (E2642)
Table grapes are an important food category in the United States. Per capita consumption of table grapes has quadrupled over the past 25 years, with annual consumption now exceeding 7 pounds.
Table grapes are an important food category in the United States. Per capita consumption of table grapes has quadrupled over the past 25 years, with annual consumption now exceeding 7 pounds. Table grapes now rank fourth in fresh fruit per capita consumption after bananas, apples and oranges.
Portions of Michigan are conducive to commercial table grape production because they have a favorable growing season, well drained soils, an extensive infrastructure for fresh marketing of horticultural crops and proximity to a large portion of the U.S. population. Other areas of Michigan will support successful backyard table grape vineyards.
Over the past 50 years, a large number of table grape varieties with potential in Michigan have been released from several grape breeding programs. Reports and nursery catalogs often suggest that many varieties are excellent and worthy of culture. In reality, however, only a small percentage of them are actually worth planting in Michigan. This publication identifies varieties with potential in Michigan by summarizing years of evaluation of numerous named and unnamed table grape varieties.
Large quantities of the native American grape varieties Concord, Niagara, Delaware and Catawba were grown years ago in Michigan for table grapes. These and other seeded table grape varieties have become less important with consumers, who now tend to prefer seedless table grapes. Therefore, this publication emphasizes seedless table grape varieties. Presentation of seeded table grape varieties is limited to a list of “top 10” choices.
Descriptions of varieties include not only their physical characteristics but also their major strengths and weaknesses. There are no perfect table grape varieties! Fortunately, a weakness does not eliminate a variety from consideration for planting.
Vine hardiness is critically important to Michigan growers. Descriptions used in this publication may be interpreted as follows: slightly hardy = significant winter injury to vines occurs at -5 to -10 degrees F; moderately winter hardy = significant winter injury to vines at -10 to -15 degrees F; hardy = significant winter injury to vines at -15 to -20 degrees F; very winter hardy = significant winter injury to vines at temperatures from -20 to -35 degrees F. Winter minimum temperature data for several locations in Michigan (Fig. 1) indicate regional trends for suitability of table grape production. Areas along the Great Lakes shoreline are generally good to excellent for table grapes. Areas inland in the lower one-third of the Lower Peninsula are generally acceptable for varieties that are at least moderately hardy, and the Upper Peninsula and inland portions of the upper two-thirds of the Lower Peninsula are generally unacceptable for grapes. There are exceptions to these generalizations. Furthermore, even if a regional climate favors grape production, the characteristics of a specific vineyard site must be evaluated.
Time of fruit ripening in this publication is for grapes at the Southwest Michigan Research and Extension Center at Benton Harbor, which has a growing season of approximately 2,600 growing degree-days (base 50 degrees F) from April 1 to September 30. Fruit maturity classes are: early = fruit ripens from August 15 to September 7; midseason = fruit ripens from September 8 to September 22; late season = fruit ripens September 23 or later.
Fruit appearance — cluster compactness, berry size, berry color and fruit maturity — greatly influences table grape marketability. Those characteristics that influence fruit appearance are highly influenced by cultural practices, which often must be uniquely tailored to each variety. Therefore, successful cultivation of table grapes involves not only choosing a good variety but also applying appropriate cultural practices. For this reason, comments on the culture of the most desirable varieties are included with their descriptions whenever possible.
Common cultural practices in the production of seedless table grapes are: applying gibberellic acid (GA) sprays, which can reduce berry number per cluster and/or increase berry size; girdling canes or trunk, which can increase berry number per cluster and/or increase berry size; and thinning, which reduces the crop level on the vine to ensure acceptable fruit quality. Detailed information on planting, pruning, training, pest management, harvesting, storage, packaging, etc., for table grapes is available in publications listed in Appendix A.
Storage life is another important characteristic of table grapes. A typical farm storage kept near 32 degrees F will allow at least fair storage of most varieties for two weeks if efforts are made to maintain high humidity. Some varieties are capable of good or excellent storage under such conditions and will maintain quality for 3 to 4 weeks or longer.