Zinfandel – a heritage grape worth preserving

Dr. James Wolpert speaking at “Flights” seminar at last year’s Zinfandel Festival sponsored by the Association of Zinfandel Advocates & Producers. Photo: Wayde Carroll

The 21st annual Zinfandel Festival in San Francisco this week, sponsored by the Association of Zinfandel Advocates & Producers (ZAP), highlights why California’s signature grape is worth preserving.  Zinfandel is not just the charmingly fruity wine that we all love, it is a chameleon of a grape that expresses its diverse origins and reveals true complexity and signature spiciness with age.  ZAP works to preserve this diversity by sponsoring a long-term zinfandel research program – conducted by the University of California, Davis (UC Davis) – whose aim is to find the best and most unique clones for commercial propagation.

Tasting terroir

Zinfandel is highly adaptable to most growing conditions, making it the 2nd most widely planted and crushed red wine grape in California according to the California Dept. of Agriculture.  And because of its relatively thin skins and deep-rooting habit, zinfandel expresses terroir better than any other grape, according to Robert Biale winemaker Steve Hall.  Zinfandel can range from earthy in Paso Robles to perfumed in Sonoma Valley to fresh and elegant in Mendocino’s cool Anderson Valley, but its real personality reaches laser-like precision depending on the vineyard soils and elevation where it’s planted, vine age and cultural practices like dry-farming and vine training.

Old vine zinfandel

Old vines are typically defined as being 50 years of age or older but many zinfandel vineyards, particularly in Sonoma, go back to the 1880’s.  Why does age matter so much with zinfandel?

Zinfandel is by nature a vigorous grape variety with large clusters and berries that creates a wine loaded with berry flavors, luscious body and silky tannins.  But as it loses its vigor with age or hydric stress, the vine produces smaller and more concentrated berries with yields dropping from 5 tons per acre to as low as ¾ ton, for example, at Bucklin Winery’s Old Hill Ranch vineyard in Sonoma.  And with lower yields come more flavor intensity, structure and complexity.

David Gates of zinfandel specialist Ridge Vineyards said at last year’s ZAP Festival ‘Flights’ seminar that old-vines “self-regulate” providing the natural balance and fruit intensity they require for quality.  For Gates, old vines provide “more nuance, more texture on the mid-palate” and a long, savory finish.  For Joel Peterson of Ravenswood, old vines add minty, peppery and spicy complexity to Sonoma zinfandels.

Field blends

Another aspect of old vineyards that creates such uniqueness in the wines is the historic tradition of co-plantation of zinfandel vineyards with other black varieties such as carignane, alicante bouschet, petite sirah and grenache with some, like Old Hill Ranch, planted with over 25 different grapes.  Most producers co-harvest and co-ferment these field blends for complexity and structural balance in the wines.  For example, according to Gates, there is typically a higher percentage of carignane in the northern and warmer Dry Creek and Alexander Valleys which add acidity and tannins to the full-bodied zinfandel there, as well as adding aromatic lift to the nose.

Seeking clonal excellence

The quest to treasure-trove zinfandel clones began in the early 1990’s.  Zinfandel Heritage Vineyard project leader Dr. James Wolpert of UC Davis was getting feedback from winemakers about the poor quality of the four available commercial zinfandel clones from the Central Valley whose main characteristics were high-yield, large berries and poor varietal character.  But where does one source better clones?

When new wine regions are established, clonal planting material – genetic duplicates of single vines with desirable traits – come from the place of origin.  Our cabernet clones come from Bordeaux, and our pinot noir from Burgundy – whether brought over by suitcase or imported from official sources like UC Davis’ Foundation Plant Services.  But what does one do with a de facto naturalized grape?*  For Dr. Wolpert, the solution was to go on a California “safari” to find old-vine selections that had evolved uniquely over time on their own home turf.

Dr. Wolpert, speaking at Flights, said he was inspired by a trip to Tuscany where he found Italian researchers conducting a similar project – attempting to mine the best Sangiovese clones by collecting high-quality selections from various areas such as Chianti, Montalcino and Montepulciano, and studying them.  This 16-year Chianti Classico 2000 project culminated in the release of seven new, high quality Sangiovese clones.  They suggested to him that he should do the same with zinfandel because of its then association with ordinary red and pink (white zinfandel) wines in the U.S.

With the support of ZAP and the American Vineyard Association, UC Davis commenced the Zinfandel Heritage Vineyard Project in 1995 to record, study and preserve distinctive zinfandel clones which they collected from 50 notable old-vine vineyards in 14 counties throughout California.  The selection criteria at the outset included old vines greater than 60 years for their presumed virus-free status, loose clusters for disease-resistance, small berries for fruit concentration, and diversity of location.

The earlier phases of the project conducted at the Oakville Experimental Vineyard in the Napa Valley with 90 selections resulted in the release of 19 new zinfandel clones by Foundation Plant Services in 2009.  The Zinfandel Heritage Vineyard project is ongoing, with new clonal studies being conducted in the field at various vineyards in California.

Taste the Heritage

The vineyard source of each of the 19 new zinfandel clones has not been released, but UC Davis did confirm that one of them is from the R.W. Moore Vineyard in Napa Valley’s new Coombsville district.  The two producers who make single-vineyard R.W. Moore zinfandel wines and will be pouring it at the Grand Tasting on January 28, 2012 are Mike & Molly Hendry (separate from Hendry Wines) and Robert Biale Vineyards.

There will be over 60 other producers pouring at the Grand Tasting who make “old-vine” zinfandel.  They are listed on ZinTracks, the official guide to the tasting available on entry.  Here is an example from last year’s Grand Tasting.

For more information on the 21st anniversary ZAP Zinfandel Festival January 26-28, 2012 check the ZAP website.


* Most studies trace zinfandel to Croatia but it was never grown as widely as it was in California.

Article previously published on www.examiner.com