There has been an ongoing debate in some professional wine circles about the influence of the moon on how wine tastes. As the importance of organic and Biodynamic farming among wine producers has grown in recent years, so too has interest in the Biodynamic calendar from both wine producers and a wider wine drinking public. Many dismiss such claims of lunar influence out of hand, but British TV broadcaster Sky News ran an engaging segment on the subject.

The Biodynamic calendar tracks the cycles of the moon season to season, and marks the suitable times for various viticultural practices throughout the year. It breaks down the days of the year into four types of time spans: fruit, flower, leaf and root periods, plus some transitional moments that don’t fit any category. Think of the old Farmer’s Almanacs down to the hour according to the progress of the moon.

The theory is that these different categories relate not only to auspicious times for associated farming practices, but also to the most auspicious times for wine consumption. “Fruit days” are theoretically considered the best for wine drinking, as the fruity aspects of a wine show should through best in these periods. Flower days are also good; notable for floral and aromatic characteristics showing well. “Leaf days” are not so good, as one might expect, since the green and vegetal aspects of a wine would tend to be accentuated. “Root days” are the worst, relating to soil and the tough work of the roots.

My own experiences, especially when tasting the same wine on many different days, is that there is some correlation. More times than not, when I find myself thinking, “This wine is tasting great today,” it turns out to be a fruit day. Or when I think, “Wow, this wine is tasting really closed and hard today,” it turns out to be a root day. Though not always. So while there is no clear and direct cause and effect relationship, it does seem that the lunar influence can be a factor—to one degree or another.

The big problem with proving the moon’s influence is that there are many other factors that can have an significant effect on how a wine tastes to you on a given day. They include: personal health (a cold or flu can wreak havoc), personal mood, fatigue, serving temperature, the people you are with, the formality of the setting (professional panel vs raucous party), bottle variation, storage conditions and the wine’s evolution over time. Together, all these factors and more make it difficult to isolate any single one and make solid conclusions.

For instance, I find that atmospheric pressure can make a difference on how a wine tastes from one day to the next. Specifically, low pressure, especially when there is a fast drop in pressure, such as when a large, fast moving storm nears. Conversely, the high pressure typical of a clear sunny day tends to work in favor of a wine showing well. But, again, this does not always seem to be the case.

Without rigorous, controlled studies, skeptics — especially among the more scientifically minded — tend to quickly dismiss any influence of the moon on wine tasting. No doubt a large amount of this skepticism stems from the religious fervor of some adherents of Biodynamic methods, and especially from some of the more superstitious sounding tenants and folkways published in Biodynamic farming literature. I won’t even hazard to get into those here.

But I will say that my own anecdotal experiences tell me that the moon phases of the Biodynamic calendar and atmospheric pressure both seem to have some real effect on how wine tastes. Even so, the how and the why of these factors remain unclear. And usually lead to even more questions. Is it the human tasting apparatus that is affected, or the wine itself that is affected? Or is it all in the mind?

So I offer no definitive conclusions beyond my own experiences, which indicate that the moon has a real, but limited and variable effect on how a wine tastes on any given day. My only advice is to keep on tasting and judge for yourself. Or if you’re really up for the challenge, get yourself a biodynamic calendar and delve deeper.