How Heritage Old Vines Renewed California Zinfandel

Joel Peterson grew up drinking European wines. In launching Ravenswood Winery in 1976, he pondered how to capture that old world style in his own wines.

“The answer came back clear,” he says. “California’s old vine Zinfandel!”

According to Peterson, the vines are low-production, predominately dry farmed, and, because these are some of the state’s oldest vines, they are planted in ideal locations.

As he sourced Zinfandel fruit throughout the state, he noticed notable variations in the character of the wine. “Wines from Amador County have a more cherry cola character. Whereas wines from Sonoma tend to be more black berry. And, wines from Paso Robles tend to be slightly more earthy in character,” he says.

In observing growth pattern variations based on location, Peterson wondered, “Is this a matter of different location or is it a matter of different clone variations of Zinfandel in these places?”

By the mid-90’s, other Zinfandel producers were posting the same question. Plantings had swelled to 50,000 acres across the state and the grape was preparing for a post-white Zinfandel renaissance. However, commercially available vine selections were sub-standard in quality.

A research collaboration between UC Davis Foundation Plant Services and Zinfandel Advocates and Producers (ZAP) was born. The project, called the Heritage Vineyard Project, procured “rare and famous Zinfandel vine cuttings” from some of California’s oldest and most prestigious vineyards to provide growers “superior Zinfandel selections for future plantings.” Twenty years later, the project has resulted in a wider selection of higher quality Zinfandel selections as well as continuing the legacy of California’s old vines.

Safari For Old Vine Zinfandel

The original Heritage Vineyard Project researchers from UC Davis believed the best way to improve the grape was to return to its origins, a complicated task for Zinfandel.

While Primitivo is a genetic match, Italians knew the grape was not native. A more likely origin is Croatia, Crljenak Kaštelanski is clonally identical, but commercially viable vines were not available.

Turns out, ideal source material was closer in reach. The team embarked on “Zinfandel Safaris” to more than one-hundred sites throughout California in search of pre-Prohibition planted vines with small berries and loose clusters free of visual disease and viruses.

Heritage Vineyard Project

Old vine cuttings were taken from fifty different vineyards in fourteen counties ranging from Amador to Santa Clara and Mendocino to Riverside and brought to the UC Davis Oakville Research Station in Napa Valley, California.

The project involved three phases, each keeping with nineteenth century viticultural practices. Phase one tested grape variability, phase two tested clonal performance and scalability, and phase three expanded the project to vineyards beyond the Oakville experimental vineyard to examine the role of climate in growing Zinfandel.

The results significantly aided the industry with a greater diversity of superior selections of Zinfandel. The initial release in 2009 was nineteen selections. Five years later, four more selections were added— Lytton, Moore, Teldeschi, and George Zeni. An array of these selections are now planted in vineyards throughout California.

“It turns out site is almost more important than whatever clonal variation we have in California. We thought there might be clonal variation; however, the project showed very little. There might be two variations but the differences are fairly small,” shares Peterson.

Rebecca Robinson, executive director of Zinfandel Advocates and Producers (ZAP) sees the project as a success. “It achieved the primary goal to provide superior Zinfandel selections to growers as the basis for future plantings.”

Beyond Phase Three

The project’s last vintage was 2017. However, experimental vineyards live on at Bedrock Vineyards, Peachy Canyon Winery, and Ridge Vineyards.

As a founding member of ZAP, Joel Peterson was involved in the Heritage Vineyard Project from the beginning. He shares the experimental vines in his Bedrock Vineyard are performing very well and hopes these are the old vines of the future.

“I like to say, I am just passing through. I am a momentary caretaker of these vines. They will be there long after I am gone,” says Peterson.

Peachy Canyon Winery, in Paso Robles, planted Heritage Vineyard Project clones in two different estate vineyards. Over ten years ago, they allocated the ‘D Block’ of their Home Ranch Vineyard to nineteen of the experimental clones planted intermittently over one acre.

Jake Beckett, co-owner of Peachy Canyon Winery, says they had some fun vinifying each clone into separate wines to educated tasting room visitors. Their preferred clones are blended into the Old Schoolhouse Zinfandel for commercial production.

“We have always been into Zin and we love the older vines,” Beckett says. “We appreciate history. It is a bit discouraging seeing these old vines getting torn out, whether they were being replanted or houses where being built. We wanted to be a part of that preservation and stay involved in education.”

Ridge Vineyards embraced the project because “from our inception in 1964, we have sought to work with beautiful historic vineyards,” says Dave Gates, senior vice president of vineyard operations for Ridge Vineyards. “We found this was a great way to continue to preserve this work and help keep those vineyards going as they die out.”

As part of phase three, Ridge planted eighteen heritage clones in an experimental vineyard on their property to measure performance.

“Thanks to this project there are now 50-60 clones available. So, there is a lot more to choose from,” he shares.

Ridge Vineyards uses Heritage Project clones in their Lytton Springs and Paso Robles Zinfandels.

Cherish Old Vines

Another accomplishment of the Heritage Vineyard Project was preserving old vine Zinfandel selections for future vineyard plantings. Some of the original vineyards no longer exist, making this project even more valuable in continuing the legacy of old vines.

“This was so important. The old vines will not live forever. We want to be able to replant and save their heritage going forward,” says Robinson.

Peterson’s passion for old vines is driven by the fact they make great wine.

“If you want your best quality vines and ultimately the best quality wine, which California bases its reputation on, then you have to take care of the heritage vines planted at least two generation ago up and down the state, he says. “If you are going to save anything, it should be those vines because they are economically viable, they produce some of California’s best wine, and they contribute significantly to the landscape of California.”

Dave Gates, who has been with Ridge Vineyards nearly thirty years, shares a similar philosophy.

“I am a viticulturist. I love old vines because if you do a good job taking care of them and pruning them, they make amazing wines without a lot of other input. You don’t have to work them like you do with young fruit,” he says. Adding, “Each of the heritage clones have survived for a long time for many different reasons, based on the founders that were farming them. That is a great story in and of itself.”