(GoodFruit) - When choosing a wine grape clone, Washington growers have little Washington-based field research to help guide their decisions. But useful information is available, if you know where to look and how to interpret the data.

Jeff Sample, owner of Terroir Nouveaux Nurseries, has around 75 clones and 35 varieties in the mother block of his certified grapevine nursery in Sunnyside, Washington. When he started his nursery in 2002, he had two main goals: offer varieties and clones that weren’t already in the foundation block managed by Washington State University; and, provide clones associated with high quality wines, such as the Wente and Dijon clones of Chardonnay.

Just as tree fruit nurseries improve apple varieties with new strains that are earlier maturing or more colored, clones of wine grape varieties give growers and winemakers the chance to fine-tune grape production by choosing specific attributes within a variety. Technically, a clone comes from a single individual—the mother vine—by asexual propagation (cuttings, grafting, and such) and is chosen for characteristics that set it apart from the standard variety.

Clones can be earlier or later maturing, be more or less vigorous, or have smaller berries or looser clusters, among other attributes. Some perform so well that they become known and distributed internationally, like the Dijon clones for Chardonnay or the German Geisenheim clones for Riesling.

“Fifteen years ago, clonal information was scattered around in many different places,” Sample said during a meeting of the Washington Association of Wine Grape Growers. “It was challenging back then to match numbers of French clones with those at the Foundation Plant Services at the University of California, Davis.”

But today, with YouTube videos and seemingly endless information on the Internet, he says it’s much easier to evaluate clones and their potential in Washington’s climate and soils.

Foundation Plant Services at UC Davis is part of the National Clean Plant Network for Grapes and, along with the Clean Plant Center Northwest at Washington State University’s Prosser research station and other centers, the network makes new clones and varieties available to the U.S. grape industry after new selections are imported, quarantined, and virus-treated.