VOLGA, S.D. - Jim and Nancy Schade opened their winery with the goal of bringing a touch of Napa Valley to the South Dakota prairie.

Visitors to Schade Vineyard, just a half hour from the homestead where Laura Ingalls Wilder penned many of her childhood stories, can tour the property, take in some Midwest hospitality and sample an array of potent potables made from locally grown grapes, rhubarb, plums, buffaloberries and chokecherries.

"I think the rhubarb wine is most unique to South Dakota," Nancy Schade said.

Schade was the third vineyard to set up shop in South Dakota after the Legislature passed a 1996 law allowing farm wineries. South Dakota's burgeoning industry, now a dozen wineries strong, produced 39,785 gallons in 2006.

About 70 acres of grapes are growing in a state more famous for corn and soybeans, but that number could soon increase. Nearly 140 people showed up for beginning grape-growing workshops offered this spring both east and west of the Missouri River, said Rhoda Burrows, an Extension horticultural specialist at South Dakota State University.

"There's a lot of people that are interested," she said.

Burrows recommends that new growers select early maturing varieties with good cold hardiness and start small with one-half to a full acre, "partly for the learning curve, and partly to make sure that they really want to do it before they go into it full bore."

While vineyards in California and Oregon have had more than a century to perfect how to grow their grape types, Burrows said, varieties hardy enough to survive South Dakota winters are the result of recent breeding, much of it at the University of Minnesota.

"Instead of having hundreds of years of experience in knowing how to grow this vine, we may have 10 years or five years," she said. "So we're still learning about the cultivars themselves and how best to grow them. And then you pit that against growing them in a state where they've never been grown before, so there's learning curves there."

South Dakota's industry is mostly a niche market, but wines produced by the state's two largest wineries - Prairie Berry Winery in Hill City and Valiant Vineyards in Vermillion - have been competitive internationally, Burrows said.

The Schades, who bottled their first batch in 2000, produced 3,000 cases last year using several varieties of grapes grown on their 2-acre vineyard and grapes and other fruit bought from a dozen or so area growers.

"All of our grapes and fruit are grown within 200 miles of our vineyard," Nancy Schade said.

For Don South - as with many of South Dakota's growers - winemaking was a hobby that blossomed into a side business.

The Renner man had been making wine since 1998 and began planting his own grape vines in 2000.

"We've got about 3,200 vines in the vineyard, so it was time to find an end market for it," South said.

So South, whose "other full-time job" is president of the Sioux Falls Sign-O-Rama franchise, opened Strawbale Winery late last year, construction a building out of straw bales covered with stucco.

Strawbale has built a loyal following, producing sweeter dessert-type wines such as a black currant wine, strawberry apple wine and a honey wine, South said.

South and his fellow winemakers network through the South Dakota Specialty Producers Association, but they're branching off into the South Dakota Wine Growers Association in an effort to create new markets and build the industry.

Unlike in other industries, winemakers welcome new entrants, South said.

"Another winery is not a competitor, because one and one basically makes three in this business," South said. "You need wineries about every 30 miles apart so you can get a viable wine trail going."

Schade Vineyard, which also specializes in sweet wines, has benefited from its proximity to South Dakota State University. Students from SDSU majoring in horticulture and landscaping have helped out as employees and interns.

Kelly O'Donnell, a recent graduate who plans to teach ag education in Arlington this fall, spends her mornings tending to the Schades' 1,800 or so vines. Maintaining a vineyard is a labor-intensive endeavor, as you have to consider weed control, pruning, downy mildew, potential damage from creeping pesticides and scores of birds just waiting to swoop in from a nearby tree to munch on the sweet fruit.

Vineyards can be profitable on a per-acre scale - with grape fields in full production bringing in $8,000 to $10,000 per acre - but growers also need to factor in their time and initial investment, Burrows said.

New growers have upfront costs that can top $7,000 or $8,000 an acre, and vineyards typically don't produce their first full crop until about the fourth year - even if the land is managed well.

That's why most vineyard operators are either retired or have another job.

"It makes a good supplemental income for most people," Burrows said.

The Schades have taken a conservative approach to growth, choosing to bottle and label by hand rather than investing immediately in high-priced equipment. It's important to keep costs down, as rural Midwesterners aren't accustomed to paying anything near what someone in the Napa Valley might consider inexpensive.

"We have to be very aware of that," Nancy Schade said.

South Dakota wineries can sell their products at the vineyards and through retailers, but they can't ship bottles within the state. They can ship to most surrounding areas, but the laws and licensing fees vary.

Prairie Berry Winery in Hill City, which ships much wine out-of-state, uses compliance software to stay on top of more than 10,000 rules and laws that need to be verified before sending out a bottle, said Michele Slott, Prairie Berry's director of Marketing.

The winery, on Highway 16-385 near Mount Rushmore and Crazy Horse, also sells to many tourists visiting the Black Hills.

"The vast majority of our traffic is from Memorial Day to Labor Day," Slott said.