“Many people probably think Arizona’s climate is just too hot to grow wine grapes,” says Cochise County grower Rod Keeling. “But, here in the far southeastern part of the state, where the bulk of Arizona’s wine grapes are produced, it’s almost too cold.”

Rod is president of the Arizona Wine Growers Association. Its 40 winery members produce grapes in the areas around Sonoita (south of Tucson) and Willcox (east of Tucson) and in the Verde Valley area of north-central Arizona.

The winery production building (lower left), the home of Rod and Jan Keeling (middle right) and the barrel cellar make up the complex of buildings in this photo from the Keeling Schaefer Vineyards.

Among the most-seasoned growers in Arizona’s young and up-and-coming wine industry, Rod and his wife, Jan, own and operate Keeling Schaefer Vineyards. The Keelings use the fruit to make their estate-grown-and-bottled Rhone-styled wines.

They began planting the first of their 21 acres of mostly ENTAV-certified French grapevines at the 5,000-foot level on the western slope of the Chiricahua Mountains in 2003. That elevation, southeast of Willcox, puts the tender young shoots of each season’s new crop at an increased risk of late spring frosts.

“For the first five years we had no problems with frost,” Rod says. “But the next five years, particularly 2009 and 2010, were pretty bad for frost damage.”

Although Arizona’s first winery was bonded in the early 1980s, it took another two decades for the industry to begin picking up steam. The Keelings established their winery in 2005, becoming only the ninth in the state to be bonded. Since then, the number of bonded Arizona wineries has increased almost tenfold.

“Around the time we started planting our vines, there were no more than about 100 acres of producing vineyards in the entire state,” Rod says “Now, there are close to 1,600 acres.”

In the meantime, wines made with Arizona-grown grapes have begun attracting attention in numerous national and international publications and competitions.

He attributes the quality of these wines to a combination of the unique climate, high elevations and volcanic soils of Arizona’s wine grape country.

However, as the Keelings experienced, these same factors can also pose their own particular set of challenges to growers.

For instance, they dealt with the increased threat of late spring frost damage to their vines by installing a 30-foot high orchard fan in each of their two vineyards – one in 2012 and the other the following year – to take advantage of the area’s unusual spring temperature inversions.

“The thermometer may read 18 to 20 degrees at ground level, but if you go up 20 feet or so higher, the air temperature may be as warm as 35 degrees,” Rod said. “The 18-foot diameter propellers mix the warmer temperature with the cooler temperatures to help prevent frost damage. Over the past four to five years, we haven’t used the fans more than about a total of 90 hours. But each paid for itself, the very first time we needed it.”

As further insurance against frost damage, Rod delays pruning his vines as late as possible. This year, for example, he pruned the last of his vines in mid-March. Also, in advance of a frost forecast, he sprays his vines with a mineral-based oil to slow bud development and to help protect any green bud growth for two or three days .

Another distinguishing feature of Arizona’s wine-growing area is low soil potassium levels. Uncorrected, this condition can lead to high pH levels in the fruit at harvest, impairing wine quality. To help prevent that, he applies a liquid potassium fertilizer to his soils through his drip system. He treats the soil in early April to support early vine development and then again just before veraison.

“This approach keeps the vines in pretty good shape,” Rod says. “Until we started doing this, we were losing some individual Syrah vines, although the quality of their fruit still remained high. Our other varieties aren’t affected as much by low potassium levels.”

Hail can be another threat to Arizona’s grape crop. In several of the last 15 seasons, it has caused significant damage in some vineyards, Rod adds.

Summer monsoons are another unusual characteristic for Arizona’s wine grape season. Growers here receive most of their average annual rainfall of just under 13 inches during the winter, when Pacific cold fronts pass through, and again during about a two-month period beginning in early July. That’s when prevailing winds shift to the southeast and bring up tropical moisture from Mexico. Those wet conditions encourage fungal growth in the vineyards, increasing the risk of Botrytis bunch rot, Rod notes.

“During the monsoon season, the days are bright, warm and sunny until the afternoon, when clouds, thunderstorms and even torrential downpours cool things off considerably,” he says. “In the Willcox area, average temperatures during the day at this time of year reach the upper 80s, but drop to the high 50s and low 60s at night. This wide diurnal swing in temperatures contributes to the full flavor of the grapes grown here.”

In deciding which grape varieties to grow, the Keelings followed the lead of another area grower who had planted his vineyard several years earlier. “We tasted his wines and selected our clones based on those wines we liked best,” Rod says. “Other growers had found that Bordeaux varieties, like Cabernet Sauvignon and Merlot, didn’t do well in Arizona, while the Rhone varieties seemed pretty well adapted to our conditions.”

This year, the buds of his earliest variety, Viognier, began opening in the third week of March. That’s about a week to 10 days earlier than normal and follows an unusually wet winter and warmer-than-normal temperatures since the end of the storms in late January. The Keelings also grow Grenache, Picpoul Blanc Syrah and Mourvedre, their latest-maturing variety.

The Keelings rely on a 500-foot deep well, tapping a huge aquifer underlying the Willcox area, to supply water for their drip irrigation system.

Using results of extensive soil and plant tissue testing, the Keelings have pushed average fruit yields up to the 3½-to-4-ton-per-acre range. That’s higher than the state average, Rod notes.

“Our two vineyards have produced really good crops, both in yields and quality, in each of the past five years,” he says. “I think we’ll see yields, overall in the state, increasing as growers learn how to grow grapes better. Most of us started out with little viticultural knowledge.”

His biggest disease concern is Botrytis bunch rot. Typically, he controls what little insect pressure he faces in his vineyards with only spot treatments. Only once did he have to spray his entire vineyard with an insecticide. That was eight or nine years ago to control an outbreak of leafhoppers.

The Keelings and eight other local wine makers with tasting rooms in Willcox, working with the Willcox Chamber of Commerce and Agriculture, formed a wine marketing co-op in 2009.

Their program is designed to draw in customers from three major regional markets – Tucson, an hour or so drive from Willcox; and Phoenix, Ariz., and El Paso, Texas, each roughly a 3½-to-4-hour drive from Willcox.

Supported by their self-funded $80,000 budget, their primary promotional activities are two annual week-long festivals – one in May, the other in October – celebrating wines made from grapes grown in the Willcox area. The marketing efforts also include television advertising in the Tucson market and a 16-page insert, which is part of a food guide placed in motels and hotels throughout the state.

Last fall, the Willcox area was approved as an American Viticultural Area, joining in AVA status with Sonoita, which received its AVA designation in 1984. Currently, efforts have begun to establish AVAs in the Chiricahua Mountains and in the Verde Valley.