John Williams will throw a once-in-a-quadrennium party Wednesday evening. Williams, winemaker and owner of Frog’s Leap Winery in Napa Valley’s Rutherford district, has been celebrating his favorite “free day” every four years since 1984 by inviting “a few hundred of our closest friends” to a bacchanal on the winery grounds. The entertainment last year — excuse me, in 2008 — included the University of California marching band.

Recommendations for a leap wine on a leap year

“I figured I could throw a small party every year, or a big one every four,” Williams explained in a phone interview. “I tried to interest the other ‘Leap’ wineries” — Stag’s Leap Wine Cellars and Stags’ Leap Winery, both also in Napa Valley — “and we even tried to get Leap Year Day declared a national holiday.

But that’s pretty much the purview of the greeting card companies, and since it comes only once every four years, they weren’t interested.”

And why not celebrate Leap Year Day? Fans of Frog’s Leap will recognize Williams’s sense of humor, from the “Ribbit” stamped on corks to his sometimes-playful names for wines. The latter include Leapfrogmilch, a play on the German wine Liebfraumilch, which he used for an off-dry white blend (which he no longer produces, because even with that name, it didn’t sell). On his late-harvest dessert Riesling, the German tongue-twister Trockenbeerenauslese becomes Frogenbeerenauslese.

Yet Frog’s Leap is best known for the quality of its wines and for keeping to a traditionalist style when most of its neighbors have made plush, overtly fruity wines with rising alcohol levels. Early in his career, Williams crossed paths with some modern American wine icons. A native of western New York, he studied winemaking at Cornell University and did his work-study with the Taylor family, learning the trade with labrusca grape varieties. Then he moved to California to work at Stag’s Leap Wine Cellars for Napa pioneer Warren Winiarski and his famous consultant winemaker, Andre Tchelistcheff.

“My first day on the job, I bottled the ’73 cabernet that won the Paris tasting,” the famous face-off of 1976, he recalls. “Warren offered to pay me in wine, but silly me, I took the cash.”

Williams was an early advocate of organic viticulture and dry-farming, or forgoing irrigation. He attributes many of the changes in winemaking style to changes in agricultural practices, as winemakers develop new techniques to correct for imbalances in the grapes caused by modern farming methods.

“All the great wines that established the reputation of Napa Valley were from dry-farmed, unirrigated vineyards, and that’s the way we continue to farm,” he says. “Irrigation was introduced in the ’80s and became popular in the ’90s.

“With irrigation, the root ball becomes less developed and can’t find nutrients, so you have to put the nutrients in the water,” he says. “We call it fertigation.” The water and nutrients increase vigor in the vines, leading to “green” flavors that need to be “corrected” with techniques such as micro-oxygenation and reverse osmosis.

Williams says rising alcohol levels seen in many wines are another product of irrigation. His wines, in contrast, are more modest. The 2010 Frog’s Leap Sauvignon Blanc clocks in at 12.8 percent, while the 2009 Zinfandel is 13.6 percent. Many other winemakers’ zinfandels are now well above 15 percent.

Seriousness aside, Williams continues to insist on having fun. “I’m 59,” he says. “We have to celebrate the free day.”

Frog’s Leap is not the only winery where celebration is in order. Stag’s Leap Wine Cellars, though no longer owned by Winiarski, continues to produce stellar cabernet sauvignon. Stags’ Leap Winery makes one of California’s best petite sirahs. (The wineries are most easily distinguished by their full names and the placement of the apostrophes.) In Washington state, Poet’s Leap winery makes one of this country’s best Rieslings.

Putting “leap” in a winery name is no guarantee of success, however.

“There once was a Pigs Leap winery, but it never really got off the ground,” Williams quips.

Recommendations for a leap wine on a leap year

McIntyre blogs at dmwineline.com. Follow him on Twitter: @dmwine.