(FORTUNE Magazine) – Winemakers are often considered an odd lot. A good number of them hug trees, wear Birkenstocks, and so on. But there is a movement sweeping the wine world that makes Greenpeace look moderate. It's "biodynamics," a form of viticulture in which all the work in the vineyard and the cellar is performed in accordance with the cycles of the moon and the alignment of the planets.

Some biodynamic practices, such as spreading nettle tea in the vineyards, are merely unusual. Others, such as "preparation 500," are downright bizarre. This treatment is created by burying manure in cow horns at the fall equinox on lines where astral influences cross in the vineyard. The horns are dug up at the spring equinox and their contents heavily diluted with rainwater. Before being spread on the vines, the preparation is "dynamized," stirred in alternate directions for an hour, preferably by hand. Minute amounts are used, perhaps a handful per acre. Those employing the preparation believe that it transfers the "life giving" forces of the earth to the vines, making them healthier.

It is unlikely that anyone would have taken much notice of biodynamics if so many of the wines it produced were not among the best on the market. Many of the top estates in France, including Domaine Leroy in Burgundy, Chateau de la Roche-aux-Moines in the Loire, Maison Chapoutier in the Rhone Valley, and Domaine Zind Humbrecht in Alsace, are practitioners.

The theory behind biodynamics was developed by Rudolf Steiner, an Austrian philosopher (1861--1925) who founded the Anthroposophical Society and the Waldorf schools. Steiner never specifically addressed grape growing in his writings; his agricultural precepts originally found adherents among home gardeners. And while Steiner couched his theories in scientific jargon, there are no scientific studies behind his conjectures. Rather, Steiner's wisdom is believed to come from his ability to see the "inner life."

The self-appointed leader of the current movement is Nicolas Joly, owner of Chateau de la Roche-aux-Moines and author of Wine From Sky to Earth, a bible for aspiring biodynamists. Like Steiner, Joly communicates in poetic metaphors: "Herbicides destroy the microbial life of the soil. Without this, the vine cannot feed itself. If my hands are tied behind my back, I cannot eat." Many practitioners in this country, including Mike Benziger of Benziger Family Winery in Sonoma and viticultural consultant Alan York of Mendocino County, play down the mystical side. Not so Joly. "Vine diseases come from not respecting life forces," he claims. "In biodynamics, we are using the energetical world and reconnecting that to the vine. You have a lot of invisible forces. Disease is just a lack of life forces." Such pronouncements, as well as Joly's compelling personality, attract throngs of ardent followers, which is upsetting to some in the wine world. Alan Meadows, a prominent Burgundy critic, says, "It has cult-like aspects; it reminds me of Jimmy Swaggart."

The biodynamists say their approach enhances the uniqueness of wines, making them express their origins more clearly, a concept the French call terroir. And while that concept is one of the most respected in fine-wine circles, it is also a handy marketing argument, one that's particularly valuable at a time when French wines are rapidly losing market share to less expensive offerings from the New World. If a wine is valued for its expression of a specific place, it can't be supplanted by another wine from the other side of the globe.

Biodynamics is a labor-intensive way to work the land. The biodynamic calendar often calls for working at night and on weekends. The calendar specifies times for tasting too, which can raise eyebrows. Says Meadows: "The biodynamic growers want me to taste their wines only on fruit or flower days, never on leaf or root days. It's a concern for me as a critic when the grower says, 'These tasted much better last week.' You don't know if it's true or if it's code for 'My wines suck this year.' "

Oddly enough, Burgundy, one of France's most tradition-bound regions, is the hotbed of the movement. That may be because several decades ago--after centuries of intensive farming followed by years of heavy pesticide and herbicide use --the soil in Burgundy vineyards had become exhausted. Wineries began looking around for solutions. Two of the top estates, Domaine Leroy and Domaine Leflaive--whose wines sell for as much as $1,000 per bottle--took up biodynamic methods, and others followed.

Anne-Claude Leflaive of Domaine Leflaive points to a plot in one of Burgundy's top vineyards, Batard-Montrachet, that was so diseased that she was ready to rip it out in 1989. Using biodynamics, she claims to have saved the vineyard, whose wines are now some of the most prized in her portfolio.

Although there is a spiritual ring to the biodynamics arguments, with their frequent references to "cosmic energies" and "natural equilibriums," the treatments themselves are far from warm and fuzzy. The standard remedy for insect pests, for instance, involves charring several of the offending insects in an oven (wood burning), grinding their ashes with a mortar and pestle, and then spreading the remains around the vineyard (when the moon is in Scorpio).

Astronomers have spent millennia trying to measure the effect of the moon and planets on the goings-on down here. They will tell you that no one has yet found any measurable effect that could account for the results the biodynamists claim. Anthony Aveni, a professor of astronomy at Colgate University and author of Behind the Crystal Ball, a study of belief systems, says, "There is no scientific way that we can say that these things connect. There are many reasons why people believe in these systems. My gut feeling is that the scientific basis is the least of them."

How, then, to account for the quality of the wines? Says Meadows: "It's incontrovertible that winemakers who follow biodynamics make better wine. What's less clear is why. All of the winemakers I have met who follow biodynamics are fanatical; every detail is obsessed over. So is it the methods or this fanatical obsession with detail?"

In the end, of course, the proof is in the pudding, or in this case, the bottle. In the next issue FORTUNE will report the results of a blind tasting of biodynamic wines vs. conventionally made wines.

JEAN K. REILLY is a freelance wine writer and educator based in New York City.