A quarter of a century ago, on a spring morning in New Zealand, Annie and James Millton watched clouds of insecticidal spray envelop the flowering vineyards, their own included, in the prime wine country of Gisbourne.

“The chemical companies told you to do it, and how often to do it, and everyone obeyed,” Ms. Millton said recently. “But these sprays were getting at the effect, not the cause,” Mr. Millton added.

“We noticed, too, that when we were up before dawn to work in our vineyards under a full moon,” Ms. Millton said, “the moths were especially active. … We began to see connections between agriculture and the rest of the physical environment.”

With those initial insights, the couple began turning their Millton Vineyards into a biodynamic winery. Based on a series of lectures given in 1924 by the Austrian philosopher Rudolf Steiner (better known for his arts-oriented Waldorf schools), biodynamics incorporates the practices of organic agriculture. But it goes a step further by trying to harmonize the grower’s work with other elements, such as gravity, magnetism, and, as the Milltons first noticed in the pre-dawn, lunar phases. Biodynamics has its skeptics as well as its followers, especially when it comes time to bury a cow horn filled with dung in the vineyard in order, according to Steiner, to jump-start organic processes in the earth.

Biodynamics was not a road well-traveled back when the Milltons embarked upon it. “We were the first in New Zealand to push off the edge of the swimming pool,” Mr. Millton said. But the couple was less lonely one day last week, as they poured their wines along with 78 other mostly biodynamic winemakers from 12 countries at the Return to Terroir Third American Tasting held at the Altman Building in Chelsea. The well-attended event seemed to include everyone connected with the wine world except purveyors of vineyard chemicals.

Not that biodynamics is aimed only at keeping vineyards chemical-free for the sake of hoped-for health benefits. According to the Loire Valley winegrower Nicolas Joly, founder of the worldwide association of biodynamic winemakers which hosted the tasting, chemical treatments of the vines also interfere with the typicity of individual vineyards. Without that individual expression of their little piece of earth, or what the French call terroir, wine would be no more interesting than soft drinks. Mr. Joly’s own property, the highly distinctive Coulee de Serrant, has been a showcase for biodynamic wines since the mid-1980s. And not only wines. I confess to having pocketed a branch from one of the rosemary plants lining a dirt road amid Mr. Joly’s vines. Pale green verging on purple, it perfumed a leg of lamb roasted in my home kitchen like no other rosemary I’ve ever encountered.

“The appellation system emerged in France in the 1920s,” Mr. Joly said, dressed in slacks and a baggy gray turtleneck sweater at the tasting. He looked more like a Sorbonne philosophy professor than winemaker. “The creators of the system understood that the original and inimitable taste of wine comes from its particular terroir. But by the 1950s, the marketing of synthetic chemicals to grape growers was interfering with the appellation concept. Vines were so impacted by artificial regimes that they no longer could express their true selves. It was bad enough when chemicals were sprayed on the exterior of the vines, even worse when they began to be delivered into the sap itself. How could the vine then assert its natural self?”

Awkwardly called Return to Terroir/Renaissance des Appellations, the association founded by Mr. Joly in 2001 welcomes organic winemakers as well as those who move on to the broader realm of biodynamics. Just over half the wineries at the tasting were French, ranging from the obscure Domaine Beauthorey in the Languedoc region to the famed Domaine Leflaive in Burgundy. Eleven American wineries were on hand, although one of the greatest domestic biodynamic wines, Napa Valley’s Quintessa, was absent.

And what about the taste of biodynamic wines? At their best, they can dazzle with their vividly pure and individual flavors. But so can plenty of conventially made wines. Let it be said, too, that Americans who bought more than 7 million cases of the technically perfect Australian Yellow Tail last year may need to adjust their palates to wines whose edges have not been perfectly smoothed out. Biodynamic wines, in fact, can be downright quirky. Get to know them, however, especially with food, and you may find that it’s difficult to return to the more commercial stuff.

Recommended Wines

MARC TEMPE PINOT BLANC 2002 ($17.99 at Suburban Wines) If any single wine could convert a doubter to biodynamics, it would be this Alsatian white: enormously lively, practically surging with smells and tastes of honey and apricot. Slightly spritzy, too. This was my first wine of the tasting, and it was hard not to keep sipping it all morning.

FLOR DE PINGUS 2003, PESQUERA-VALBUENA ($52.99 at PJ Wines) In keeping with biodynamic practice, this wine is free of added yeasts and enzymes, and also has been vinified without temperature control, a technique considered essential by many modern vintners. Rich, dark, polished, and luscious, this Spanish beauty is, like the wine above, a potent argument for letting nature take its course.

BENZIGER SAUVIGNON BLANC 2005, SONOMA ($8.79 at Zachys) Exceptionally fresh and lively, with plenty of lemony body. And so well-priced. Proprietor Mike Benziger went biodynamic in 1994, making him a California pioneer.

CULLEN CHARDONNAY 2003, MARGARET RIVER ($50 at Raeders Wines) Australia’s raciest, sauciest “chards” seem to come most often from this maritime influenced region. This one is full, minerally, and persistent. Cullen is a noble exception to the disinclination of Australian wineries to go biodynamic.

MILLTON VINEYARDS CHENIN BLANC 2004, TE ARAI VINEYARD Pumps out big volumes of minerally, richly textured flavor. Barrel fermented. One of the world’s better chenin blancs. Will some importer please bring it to New York?