If wine is a symphony, and a winemaker is the conductor and terroir is the band, then grape clones are the stage managers.

Depending on the conductor you speak to, clones are either essential to the success of the operation, necessary but mercurial entities that must be rigorously controlled or ghostly reflections of the real McCoy.

What gives? For starters, we’re just beginning to understand clones. While winemaking has been going on for thousands of years, and humans around the world have poured billions into everything from understanding the geology of grape varieties and the implications of climate change for the world’s most popular varieties, to ever-more intricate farming and production techniques, there are 10,000-plus grape varieties out there, all of which react differently in different soils, depending on what type of rootstock they are grafted to, if they’re own-rooted, whether they are clones or grown using «massal selection».

Also, there are more than 1000 clones of Pinot Noir alone! I’m no math whiz, but even I can see the data set tracking the potential aromas, flavors and traits emerging from these combinations could be as infinite as Pi.

That’s a ghastly enough challenge for winegrowers, but it’s even more complicated than it appears. A clone (or cultivar) is a vine created through vegetative propagation from the cutting or bud from one «mother vine». This vine is picked carefully, in a process known as clonal selection. The Germans popularized the process in 1926, in which one particularly primo plant is selected among its more lackluster compatriots to be identically replicated and planted elsewhere. This top dog is usually picked for its ability to resist disease and climactic challenges, and the quality of its juice.

Few would say these carbon copies are identical, because climate, soil and the rootstock they’re connected to can significantly impact a clone’s expression. And in a data-crazed industry, there are few comprehensive studies comparing large sets of clones across climates, soils and rootstocks.

In other words, there’s a lot of guess work inherent to the process of picking the «perfect» clone. The result, as in other subjective areas of human inquiry – religion, sex, rock n’ roll – is a lot of people passionately advocating their own POV.

Frankenfruit’s monster

Winemaking in the US is built on clones. Most modern wineries purchase hundreds of identical vines from nurseries and plant them in blocks; many in recent years have turned blending an array of clones into an art form (more on that below).

But other regions view clonal selection as utterly anathema to quality.

«We tried clonal selection in the mid-1990s here in Argentina,» says Daniel Pi, winemaker at Mendoza, Argentina’s Trapiche.

«There was a boom of importing European materials. But we found that the clones are a weak imitation of the Malbec vines we have. The DNA of the original Malbec is so rich and complex; it was first transported here in the 1800s from Burgundy. We use massal selection, and to me in comparison, using clonal selection to make wines is like creating a city of dollies with blue eyes and blonde hair. Beautiful perhaps, but so boring.»

In massal selection, new vines are planted from cuttings of several of the highest-quality vines in the vineyard. The end result is different because vines mutate quickly, the vineyards that use this method are much more genetically diverse, creating, Pi and other proponents say, more nuanced wines.

But clone enthusiasts argue that this subtly gradated complexity can be found as long as a variety of clones is used.

«I don’t like monoclonal wines because they can be too simple,» says Steven Gerbac, winemaker at Ballard Canyon’s 8000-case Rusack Vineyards. «You don’t get that sense of wholeness. By using multiple clones from one vineyard, I think it offers a fuller picture of the terroir.»

Gerbac says that while the site is ultimately the most essential factor in building a great wine, that clones can be used by winemakers as a great chef might use an herb garden or spice rack.

«You can tease out more of a super dark and fruity flavors with a great clone if your site may not deliver that on its own,» he says.

Anthony Beckman, winemaker at Balletto Vineyards in Santa Rosa, concurs, saying that they have selected California Heritage clones of Pinot brought over from Burgundy, propagated, field selected and propagated again during California’s early wine-growing history. His «Holy Trinity is Swan, Calera and Mt. Eden», as they deliver a blend of aromatics, spice and structure.

Essential tools

Other winemakers believe that clones, if deployed correctly, are predictable and consistent tools that can be used to showcase a vineyard’s supremacy and refinement.

Theresa Heredia, a chemist-turned-winemaker at Gary Farrell Vineyards & Winery in Sonoma, in many ways sees vineyards as laboratories. She makes 12-14 Pinots a year, each of which are either a distinct expression of place … or clones. For example, one 2016 Hallberg Vineyard Pinot is comprised of clones 667, 777, 828, Pommard and a mystery suitcase selection, while another 2016 Hallberg Vineyard Pinot is made from 777 and 667. Tasted side by side, they’re completely different: the first is lush, concentrated, red-fruit driven and powerful while the second is subtler, softer, spicier, with more floral aromatics.

«Terroir and clones are a balancing act,» she explains, adding that the Hallberg selections drive that point home.

For the director of winemaking at Hahn Family Wines in Santa Lucia though, it’s «the more the merrier for the best finished wines. Currently, we have more than 20 clones planted throughout our SLH vineyard, and each gives its own imprint of the site and adds a layer of flavor to the blend.» But more importantly, he says, is that with a symphony of clones means that the terroir itself can perform the aria, without one clonal influence dominating.

Clones can also be used to disguise a site’s weak points, others say.

© Wikimedia | Cabernet clones are hugely important in Napa.

«When the Sullivans planted the vineyard here in the late ’90s, they were looking for a Cabernet clone that would provide more structure,» says Jeff Cole, winemaker at Sullivan Rutherford Estates in Napa. «The floor can be vigorous, and they wanted smaller berries that would produce mountain-fruit like flavors.»

At Rotari in Trentino and Sicily, winemaker Maurizio Maurizi also uses clones as a hedge against climactic issues.

«We use different clonal strategies in the Dolomites and in Sicily,» says Maurizi. «Because of the sizable diurnal swing we have in the Dolomites and the elevation there, we have an excellent accumulation of aromas and flavors naturally, so we use clones that we know will be healthy and grow well. In Sicily, we work with French clones that will bring more nuance and aroma because the swing is much less significant.»

A deep understanding of a vineyard’s soil, with a baseline knowledge about clones yields predictable results, says Franco Bastias, Mendoza-based Domaine Bousquet‘s vineyard manager.

«We work with clones to obtain a specific, well-identified profile,» Bastias explains, adding that they also use clones to combat climate challenges. «Pinot Noir is sensitive to humidity and higher levels of radiation, so we work with 777 and R20 to maximize varietal expression while minimizing issues that we can run into during harvest.»

Mercurial beasts

Michael Larner, winemaker at Los Olivos’ Larner Vineyard & Winery, agrees that clones can be used to «enhance a good or great site» ameliorate the weaknesses in others, but as a geologist turned winemaker, he doesn’t believe clones are predictable between sites, or even across time at the same vineyard.

«Life takes so many shapes and clones, and is constantly evolving,» Larner says. «There are so many unknowns with clones. Are they evolving once they get to a site? And how does one clone react to one rootstock in one site, and another rootstock in a different one? A lot of the accepted wisdom on clones is anecdotal, instead of scientific.»

Paul Golitzin, president and director of winemaking at Washington’s Quilceda Creek, says that he has delved into clonal research in the past decade, and has found that his site doesn’t always deliver on a clone’s reputation.

«We love Cabernet Sauvignon 191 now, but we had to give it almost 10 years,» Golitzin says. «We were looking for body and soul, but we were getting all tannin and no soul. At seven years it started delivering more body, but it never ripened early as I was led to believe. It always ripens late.»

He adds that because he is working with all own-rooted vines, instead of rootstocks, it’s possible that his clones are more prone to delivering surprises.

Other winemakers bemoan the spotty availability of clonal material for more obscure varieties, saying it hampers their ability explore their region’s potential.

«We used a lot of Tablas Creek’s Rhône clones and, while they worked well, we’re not a Paso Robles cover band,” says Todd Bostock, winemaker at Dos Cabezas in Arizona. «We want to more with clones from Macedonia, because we think they’d be ideal for our soil, and we’ve connected with the consulate to try to get help importing plant material from the country through University of Virginia. But it’s a freaking process, and it’s taking a lot longer than we anticipated.»

Davis and Cornell, he says, have «hundreds of Cabernet and Pinot Noir clones, but maybe one each of Marselan, Graciano, Vranac. We want to explore the full range of these grapes on our terroir, not just one expression.»

Where next?

Other winemakers like Matt Dees at Jonata, the Hilt and Kimsey Vineyard in Ballard Canyon, also say that confidence in clonal traits is misplaced.

«Discussing clones make me grumpy,» he admits. «It’s impossible to make judgments. The clone that works with our soil will work completely differently next door. And it’s not just training or the type of rootstock. The route to profound wine is testing a melange of virus-free clonal material and seeing what works with your site. There’s no fast-track.»

He did say that Chardonnay and Pinot Noir clones – perhaps in part because there has been more research into their performance across terroirs, soils and rootstocks – are more predictable than say, Syrah, which he and Larner agree must be planted to be understood.

But some are beyond mercurial; some disguise themselves. The biggest creeper by far is Sauvignon Blanc Musque, and unlike, say, Cabernet Sauvignon 191, which ripens and produces different flavors and aromas at different sites and times, SBM is perpetually weird in the same way.

«I know from personal experience, and also confirming with several other winemakers and somms that Sauvignon Blanc Musqué displays far more aromatic characteristics than any other Sauvignon Blancs,» says Eric Crane, director of training at Empire Distributors. «By itself, it has stone fruit and mango notes, instead of the vegetal, grass and citrus you typically get.»

In an industry that pours billions into micro agricultural advancements and winemaking tech in a quest to find an ever-more elusive «edge» against competitors, it’s refreshing to find one relatively unexplored area of inquiry.

«There are so many elements to consider when thinking about how clones can change and be changed by the topsoil, the subsoil, the rootstock, the weather,» says Dees.»I wish I knew more. I wish we as an industry knew more. But we’re in the field working and testing; we’re at the ground level right now, but it’s important work, and I think we should continue it.  »