Blends abound, but one red is so popular it has its own shorthand: GSM. The letters stand for three grapes that hail from the valleys of the Rhône River—Grenache, Syrah and Mourvèdre—which altogether make a blend that’s today replicated worldwide. But what makes a GSM different from other red blends? We queried wine professionals for the answer and why they love this classic Rhône-style offering. What Does "GSM" Mean? While the term "GSM" is attributed to Australian winemakers, the blend has older origins. Grenache (Garnacha) and Mourvèdre (Monastrell) appear to hail from Spain genetically, but the GSM triad grew to fame together along the Rhône River in southern France. There, they thrived in the steep hills of Côtes du Rhône thanks to the rocky boulders and Mediterranean sun of Châteauneuf-du-Pape. All three varietals appeared in the region by the end of the 18th century. Winemakers in Châteauneuf-du-Pape created the French appellation system in 1936, cementing rules around the red blend. Today, 19 grape varieties are allowed in GSM, but at least 70% of the wine has to be from its three namesake varietals. Syrah is favored in the northern stretches of the Rhône, while Grenache and Mourvèdre lead more in the south. Each member of the classic trio contributes different notes and styles. Generally speaking, Grenache delivers delicate red-fruit notes, while Syrah brings black fruits, structure and spice. Full-bodied Mourvèdre grounds the blend with plum and savory notes. Steve Peck, vice president of winemaking at J. Lohr in California describes the harmony of this classic blend: "The star in this trio is most often Grenache which brings high-toned strawberry notes,” he says. “Syrah plays the mid-range–dark in color, often with white pepper notes. Mourvèdre plays the bass note bringing savage blue fruit aromas and tannic structure." You May Also Like: A Guide to the Wines of the Southern Rhône Image Courtesy of © Richard Duval Images Outside France, Where Do GSM Wines Thrive? Southern France may be the blend's traditional home, but GSM has found success worldwide. Winemakers told us that GSM does best when grown in vineyards with steep inclines, low rainfall, minerally and alluvial soils and hot summers. Hospitable for all three? Leading Syrah hubs including Spain, Argentina, South Australia, South Africa and parts of the United States. In America, Paso Robles has proved a worthy landscape for Rhône varieties. The area’s 11 districts have intense slopes and canyons to the west and warmer, gentler terraces to the east. Robert Haas saw southern France in these rugged California hills' limestone soils. In 1989, his Tablas Creek Winery planted direct cuttings from Châteauneuf-du-Pape and created a vineyard nursery for wineries around the country. Today, this “Rhone Zone” in California’s largest AVA is filled with Rhone varietal vineyards. To the north, Washington state has rapidly grown its Rhône reputation over the last 15 years. East of the state's stereotypically soggy coast, the Columbia Basin offers the extremes these varietals need. Meanwhile, in Oregon, the Rocks District of Milton Freewater, a sub-AVA in Walla Walla, even has a twist-your-ankle rocky top deposited along the fork of the Walla Walla River that mimics Châteauneuf-du-Pape. "The Rocks District has big savory, velvety Syrahs unique to all of the West Coast," says Sean Boyd, winemaker and owner of Rotie Cellars. According to Boyd, AVAs in the region—like Snipes Mountain, Horse Heaven Hills, Rocky Reach and Columbia Gorge—all have the soils, steep relief and high heat that Grenache loves. "Then we have Mourvèdre, which is probably the favorite wine of the devil, because you want it hotter than hell and on steep cliffs without rainfall." You May Also Like: Are Rhône Varieties Washington State’s White Knight? Image Courtesy of L. Taylor What's Behind the Enduring Appeal of GSM? A GSM red blend is an easy entry point into bold reds, with the three varietals smoothing and enhancing a wide range of notes. Timing plays a role in its easy-drinking nature: Syrah and Grenache both ripen in the middle of harvest season, followed by Mourvèdre. "The timeframe is perfect for producing [a balanced blend]," says Boyd. Each grape can hold its own as a single-varietal, so winemakers often find it easier to play with percentages and define their own personal style. "Much like a chef, making blends is like using different ingredients," says Boyd. "Red-fruit, balanced Grenache meets savory Syrah followed by brambleberry, gamey Mourvèdre,” he muses. “Grenache, Syrah and Mourvèdre play with each other so well." Others cite the blend’s approachability as a main selling point. "GSM always hooks me on three things: earthiness, nuance and romance,” says Patricia Butterfield, owner of Winescape Winery in Spokane, Washington. “There is something about the way that blend comes together and plays to the strengths of each varietal." Beyond the technical intrigue, GSM also benefits from the prestige and romance of the famous crus of France. “It's easy to slip right down the rabbit hole and imagine yourself, and perhaps a significant other, in France," says Butterfield. "The memory I keep on autopilot is the train ride between Paris and Avignon, with a glass of GSM in hand. A good wine on a good day." GSMs Worth Your Attention Why You Should Trust Us All products featured here are independently selected by our team, which is comprised of experienced writers and wine tasters and overseen by editorial professionals at Wine Enthusiast headquarters. All ratings and reviews are performed blind in a controlled setting and reflect the parameters of our 100-point scale. 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