The real story behind old-vine field blends
Clawing at the sky like gnarled bursts of lightning, the 130-year-old grapevines at Bedrock Vineyard in Sonoma are pillars of survival. There are nearly 30 varieties in this vineyard — burly, twisted limbs pruned goblet-style.
They look like trees in an arthritic pygmy forest.
Bedrock Vineyard was planted in 1888 and today is meticulously cared for by winemaker Morgan Twain-Peterson and his father, winemaker Joel Peterson.
The 35-acre “field blend” vineyard contains zinfandel, alicante bouchet, mourvedre, carignane, tempranillo and petite sirah, as well as more obscure varieties, such as peloursin, mondeuse, negrette, serine and more, many of which are combined to produce Twain-Peterson’s award-winning wines.
These are some of Sonoma County’s oldest vines. But the story behind them is sometimes muddied with myth.
Some say they were planted by Italian winemakers. Others believe they were planted haphazardly, because there are so many varieties in a single vineyard.
But in fact, these vines — sometimes encompassing up to 50 varieties in a single vineyard — were planted with great deliberation and foresight. And that foresight is still paying off today, according to John Olney, winemaker at Ridge Vineyards in Dry Creek Valley.
“The proof is in the pudding when it comes to field blends,” Olney said. ”People were deliberate in choosing the grapes they did because it’s clear they complement each other.”
But how did so many varieties come to be in one vineyard?
The answer is rooted in the crisis that nearly ended grape growing in Sonoma County for good.
These intermingled varieties — recognized as field blends — were no accident or haphazard experiment.
“Field-blend vineyards came out of a concerted, organized effort to produce higher-quality, well-balanced wines in the 1880s,” said Twain-Peterson, winemaker and owner of Bedrock Wine Co. in Sonoma. “It all started with phylloxera.”
In 1873, grape phylloxera — a destructive, sap-sucking insect that feasts on the roots of certain Vitis grapevine species — was officially documented in California, in a vineyard 2 miles north of the town of Sonoma. By the 1880s, phylloxera had quickly spread from Sonoma County to vineyards across the state, decimating every vineyard in its path.
Thousands of diseased vines were ripped out in California, leaving empty fields across the landscape. Bedrock Vineyard was first planted in 1854, but like every vineyard in the state, it, too, was wiped out by the scourge.
Faced with a potential death knell for California’s burgeoning commercial grape industry, state legislators went back to the basics to find a way forward for grape growers.
They established the Board of State Viticultural Commissioners, a collaborative of scientists, academics, winemakers and nurserymen who hopefully could solve the phylloxera crisis, set standards for grape imports and improve wine quality overall.
The board and its chief executive viticultural officer, Charles Wetmore, worked with growers and nurserymen to test 200 grape varieties to determine which vines would perform best, given the state’s weather and soil conditions.
They found they could control phylloxera by grafting imported grapevines onto American Vitis rootstock known as St. George. Now, the viticultural board could provide science-backed guidance to growers on which grape varieties to plant.
“Phylloxera really forced growers to wipe the slate clean and pull out vines that made no sense in California,” Olney said. “What we ended up with are these diversely planted vineyards that continue to produce extremely well-balanced wines. Field blends are the silver lining of phylloxera.”
Not only that, the solution the board came up with more than a century ago still has value today in another sense, as grape growers look for stability in a climate that is growing hotter and drier.
At Ridge’s Geyserville vineyard, the “Old Patch” is comprised of vines more than 130 years old. At the winery’s Lytton Springs vineyard in Dry Creek Valley, there are centenarian vines.
In both locations, zinfandel vines are intermixed, or “interplanted,” with carignane, petite sirah, mataro (mourvedre) and other grapes, which are used to produce Ridge’s highly regarded wines.
“Zinfandel grapes produce a lot of sugar, typically at the expense of acidity,” Olney said. “Carignane is the opposite. It adds acidity, so when it’s blended with zinfandel it keeps the wine fresh and focused, with flavors more in the red fruit spectrum. Carignane is really important grape for us. It’s going to be even more so as the climate gets warmer.”