Moon opposition Saturn is among the most useful and convenient celestial cycles farmers and wine-growers practising Biodynamics can work by. An opposition in astronomical terms occurs when two celestial bodies stand 180 degrees opposite each other in the sky. An obvious example of this is full Moon when Sun and Moon are opposite each other with Earth between them, with the moon lit up by the sun. This occurs every 29.5 days. Moon opposition Saturn occurs slightly more frequently at every 27.5 days. Biodynamic growers see Moon opposition Saturn as a time of enhanced plant growth (quantity) and crop taste (quality). 

The idea is the Moon and the inner planets which are Mercury and Venus (inner = orbiting between Earth and Sun) support or enhance what in Biodynamic-speak are “calcium processes”. These influence plant growth, building and regenerating the physical organism (plant roots, trunks, shoots, leaves, fruits etc). These calcium processes beneficially influence fertility – reproduction, propagation, germination – the substance or matter that the plant consists of.

On the other hand there is the contrast of the outer planets (outer = located beyond Earth) which are Jupiter, Saturn and Mars. These support the so-called “silica processes” influencing plant form, shape, structure and sensory capacity. 

Thus when Moon and Saturn position on opposite sides of the Earth–a cycle which recurs every 27.5 days–the forces they respectively exert ray into the Earth from each direction and a synergy occurs. For instance Horn manure 500 sprayed at this time provokes strong soil activity and plant rooting (steady, consistent yields); and Horn silica 501 sprayed at this time augments plant resistance (overall plant health) and crop quality (taste, flavour, ageing potential). Common horsetail 508 sprayed at this time shows improved effectiveness at balancing soil–plant relationships (less risk of disease, greater soil nutrient uptake). 

To sum up, working with plants in the two days leading up to Moon opposition Saturn produces stronger and more resistant growth (the lime/calcium force) and better quality and taste (silica force) by taking advantage of a moment when the two opposite force poles of lime/calcium and silica being in balance–see the lime–silica polarity for more on this.

Final thoughts: One stalwart advocate of Moon-opposition-Saturn was the much respected Peter Proctor. My own view is the two or three days before and during Moon-opposition-Saturn are a good time to get key tasks done eg. preparing land, planting vines, applying the Biodynamic preparations 500-508 to the land or crops. I like the logic of feeling I am working in a place (Earth) with balances on either side of it (a small but close Moon on one side, and the huge but far away Saturn on the other).