Ruby Cabernet resulted from a planned cross of Cabernet Sauvignon and Carignane by Harold P. Olmo in 1936. It was selected based on high yields and outstanding wine quality potential, and released for distribution in 1948. While its popularity has diminished since the 1960’s, it is still grown globally, primarily in hot climates, and is notable for its distinctive Cabernet Sauvignon flavor.
Origins and History
In 1936 Ruby Cabernet was selected from a cross of Cabernet Sauvignon and Carignane by Harold P. Olmo at the University of California Davis. The purpose of the cross was to combine the high yields and desirable viticultural traits of Carignane with the wine quality potential of Cabernet Sauvignon. Trial plots of Ruby Cabernet were planted in 1942 at the University Farm at Davis in Yolo County and in St. Helena in Napa County. These plantings began bearing fruit in 1944, and wine was made annually from Ruby Cabernet in the following years for comparison to wines of Cabernet Sauvignon and Carignane until 1948. During these experimental years Olmo noted the vine performance was as desired; Ruby Cabernet consistently exceeded the yields of Cabernet Sauvignon and grew open and semi upright which aided pruning and training. The Ruby Cabernet wines made from the trial plots were described as having good color stability, and Cabernet Sauvignon character.
Ruby Cabernet’s canes are symmetrical and lignify early abetting resistance to breakage by wind. The tendrils are thin, few in number, and weakly coiled. Shoot tips are downy with downy bronze-red leaves. The dark green leaves are large, floppy, and deeply 5-lobed with a U-shaped petiolar sinus. Teeth can often be found in the leaves superior sinuses along with sharp teeth bordering the leaf margin. The lower surface of the leaf is glabrous, petioles and veins are pink, and puckering is present on the leaf surface like that of Carignane.
The conical clusters are loose to well filled, have a thick peduncle, and are medium sized withsingle or double wings. The berries are medium in size, and range in shape from round to short oval. Berries have the potential to set irregularly, especially if the vine is grown on sandy, zinc-deficient soils. Also, the skin is thick and dark purple. Ruby Cabernet buds out in late spring and is ready to harvest late in the season; from mid September to mid October.
Ruby Cabernet is resistant to rain damage and bunch rot and is moderately susceptible to powdery mildew. It is also very resistant to Botrytis and sour rot, and shows some resistance to Pierce’s disease.
Ruby Cabernet is a high vigor vine on deep, fine, sandy loam to clay loam soils. On coarse sands, the vigor is low to moderate. The canopy is open with semi- erect shoot growth which aids in hand pruning and training and is also suitable for mechanical hedge pruning. Verdegaal (2003) considered Ruby Cabernet to be “capable of bearing large crops”, but his yield estimate of 8-12 tons per acre would be considered moderately productive in some growing regions today. Ruby Cabernet is suited to bilateral or quadrilateral cordon training and spur pruning..
Because of the vines vigorous growing behavior, moderate vigor rootstocks such as 101-14 Mgt or Kober 5BB may be preferred in vineyard sites with high growth potential. If grown on sandy or shallow soils, then more vigorous rootstocks may be needed, such as Freedom, 1103P, and 110-R.
The wines are deeply colored with a reddish hue, tasting slightly rustic with flavors of sweet red fruit that can range to darker fruit flavors. Ruby Cabernet can be made as a varietal wine, but is also commonly used in blends or to stretch Cabernet Sauvignon wines.
FPS. Foundation Plant Services, Grape Variety: Ruby Cabernet. Foundation Plant Services Grapes (2021). Available at: https://fps.ucdavis.edu/fgrdetails.cfm?varietyid=1322&bigpics=yes#26404. (Accessed: 15th April 2023)
Olmo, H. P. Ruby Cabernet and Emerald Riesling: Two New Table-Wine Grape Varieties. California Agricultural Experiment Station, College of Agriculture, University of California. (1948).
Walker, M. A. UC Davis' Role in Improving California's Grape Planting Materials, pp. 209-215, Proceedings of the ASEV 50th Anniversary Meeting, Seattle, Washington, June 19-23. (2000).
Verdegaal, P. 2009. Variety Observation Trial. https://ucanr.edu/sites/CE_San_Joaquin/files/35897.pdf
Anderson, K., Nelgen, S. Which Winegrape Varieties Are Grown Where? Revised ed., University of Adelaide. (2020).
Robinson, J., J. Harding, J. Vouillamoz. 2012. Wine Grapes. HarperCollins, New York
Bettiga LJ, Golino DA, McGourty G, Smith RJ, Verdegaal PS, Weber E. Wine Grape Varieties in California. United Kingdom: University of California, Agriculture and Natural Resources. (2003).