Sonoita, Willcox and the Verde Valley compared

Each of Arizona’s American Viticultural Areas was defined by a federal petition, and each petition describes its region against the country around it. Read side by side, those records give a fairly exact picture of how different the three are. The figures below come from the petitions and describe each region when it was recognized, not today.

Sonoita, the first

The Bureau of Alcohol, Tobacco and Firearms, which handled wine labels until that work passed to the newly created Alcohol and Tobacco Tax and Trade Bureau in 2003, established Sonoita in a rule published on October 26, 1984, effective a month later. The petitioner was the Babocomari Ranch Company, which had been growing wine grapes with the University of Arizona since 1975. At the time there were about 40 acres planted and a winery under construction.

The region lies in far southern Arizona near the Mexican border, ringed by the Santa Rita, Huachuca and Whetstone Mountains, which rise 2,500 to 4,500 feet above its floor. Older ranchers called it the Sonoita Valley, but the petition pointed out that it is technically a basin, the headwaters of three separate drainages: Sonoita Creek to the south, Cienega Creek to the north and the Babocomari River to the east. Left alone, its land is high desert grassland, while the country around it is mountain or shrub desert.

One detail from the rulemaking still reads well. Two Sonoma County winemakers wrote in to object that “Sonoita” looked and sounded too much like “Sonoma,” and suggested “Sonoita-Arizona” instead. The bureau disagreed, noting that both Sonoma appellations carry a second word, County or Valley, and so could not be confused with Sonoita standing alone. The 1984 rule kept the name.

Willcox, the big flat one

Willcox is the largest by far, and its floor is close to level. It covers about 526,000 acres in Cochise and Graham Counties, a shallow basin enclosed by ranges that include the Pinaleño, Dragoon, Chiricahua and Dos Cabezas Mountains. In a wetter age the basin held Lake Cochise; what remains of its southern end is the Willcox Playa, a dry alkali flat. Because the basin is closed, no stream has cut its floor, and slopes run from zero to 1.5 percent. Vineyard sites differ little in height from one another, which makes growing conditions unusually even across the region.

The closed basin also sets the terms for water. There is no river and no canal. Water comes from wells and the little rain that falls, most of it in July and August when the monsoon pulls humid air up from the Gulf of Mexico and the Gulf of California. The petition described the months before it, May and June, as the hardest on vines: dry air, soil moisture from winter long spent, heat rising. The flat floor also collects cold air sliding off the mountains in spring, so growers often install tall fans against frost.

When it was recognized, Willcox had 21 commercial vineyards on about 454 acres, plans for another 650, and 18 bonded wineries. Southeastern Arizona carries most of the state’s vineyards by count: in a University of Arizona survey of growers in 2022 and 2023, 43 percent of those responding farmed in Cochise County, far more than in any other.

The Verde Valley, the youngest

The Verde Valley is the smallest in area and the only one with a large river running through its middle. The Verde runs through the middle of it from northwest to southeast, and Oak Creek joins it from Sedona’s side. Where Willcox is flat, the valley is a bowl whose sides slope gently toward the river, and its ground spans some 2,000 feet of elevation where the Willcox basin floor spans under 600.

Its petition put the valley’s average heat accumulation at 5,580 growing degree days, against 1,727 to 3,544 at the weather stations in the higher country on each side. Night air drains off that high country into the basin, which gives the valley a wide gap between day and night temperatures and, near the river, a real risk of spring frost.

What the three have in common

All three sit well above Phoenix, and the Willcox and Verde Valley petitions both treat irrigation as a necessity. Beyond that, a Sonoita grassland vineyard, a Willcox basin block and a Verde Valley planting by the creek grow in different soil and draw their water from different places. That is the point of drawing the lines, and the reason a label that names one of them tells a reader more than one that simply says Arizona.