Biodynamic viticulture, established by Rudolf Steiner in 1924 and refined by Maria Thun in the 1960s, prescribes a lunar calendar for vineyard work. The calendar designates each day as a fruit day, flower day, leaf day, or root day, based on the moon's position relative to the twelve zodiacal constellations. Different vineyard operations are scheduled to the day type that matches their goal.
The prescription
Pruning happens on fruit days or flower days in the descending moon phase, when sap is moving downward. Bottling happens on fruit days, when the moon's gravitational influence is theorized to settle wine. Planting happens on root days. Racking and lees stirring happen on leaf days. The prescription is precise and largely independent of conventional agronomic timing.
What the research says
Peer-reviewed evidence on biodynamics is mixed. Some studies show no difference between biodynamic and conventional vineyard outcomes; others, particularly tasting trials, show small but consistent differences in wine evaluated on fruit days versus root days, with the same wine rated higher on fruit days. The lunar calendar's gravitational mechanism is not well-supported in physics; the moon's gravitational effect on a small volume of wine is negligible. The observed differences, if real, may have other explanations.
What we have observed
Several of the growers we source from practice biodynamics. We do not have a rigorous internal study, but we have noticed that our bottling team prefers fruit days for racking and bottling, citing what they describe as cleaner aromatic separation. We have not blind-tested this. We mention it because the practice is widespread among serious natural-wine and biodynamic producers globally, and because our growers find value in it.
What it costs
Nothing, if you simply consult a calendar. The lunar calendar imposes a scheduling discipline but no additional inputs or expenses. Producers who want the biodynamic Demeter certification need additional protocols, including specific preparations and farm-closed-loop requirements. We work with several growers who are Demeter-certified and several who follow the lunar calendar without seeking certification.