Horn silica 501 | One of the nine preparations used in Biodynamics. It is a spray preparation, made from ground silica stirred in water. This is applied directly to the land, or more precisely to the atmosphere above. Only two of the other nine Biodynamic preparations are applied to the land as field sprays: Horn manure 500 and Equisetum arvense 508. Horn silica 501 is also referred to as Horn quartz 501 or Horn silicum 501.

Silica | Silica is a naturally occuring oxide of silica (silicon dioxide SiO2), also known as quartz, silicic acid, and silicic acid anhydride. Silica occurs naturally as quartz, and can be found in certain living organisms. Silica is a key ingredient of microchips, hence the term ‘Silicon Valley’ for the location of the USA’s technology industry. In the USA the highest quality source of silicon is the Appalachian Mountains (The Economist: 1st Dec 2018).

Von Wistinghausen et al (2000, p.24-25) describe silica thus: ‘the most beautiful form of [silica] is rock crystal, the main constituent of the earth’s crust (47%). In its pure form it is wholly translucent, hard, and water-insoluble. In spite of this silica is taken up into plants (grasses, horsetails) and the bodies of animals and humans (skin, eyes, nerves). It structures the soil (sand grains) and is found in aluminium silicate and in colloidal form in clay. Plants are able to take it up in colloid form. The atmosphere also contains finely dispersed silica. The fact that silica is found in sense organs, above all in the skin and in the eyes, makes us aware of its relationship to light. Industrial uses of quartz are in glass, optical instruments and for information technology. Very finely ground quartz has a large light-reflecting surface area. This is put into cow horns, which are then buried in the soil to expose the silica to the light and warmth of summer. When stirred in water for one hour and sprayed on to plants, this preparation conveys light qualities that have been transformed by the summer processes in the soil. This light energy promotes and organizes plant metabolism.’

Why used | Horn silica 501 is the yin to Horn manure 500’s yang. While horn manure 500 influences the lower part of the vine and its roots, horn silica 501 influences the upper part of the vine, namely its shoots, leaves and the wine grapes. Whereas Horn manure 500 is sprayed when the afternoon sun is sinking, in thick drops and directly on the dark, tangibly heavily earth to pull the vine roots down into the bowels of the Earth, Horn silica 501 is sprayed at sunrise and upwards and into the bright intangible atmosphere to pull the vine shoots skywards. Steiner (1993, p.74) said that horn silica 501 complements and supports the influence coming from the soil as a result of the horn manure 500. Horn silica represents a concentration of the forces within sunlight (Thorton Smith: 2015, p.12).

Whereas Horn manure 500 mobilizes matter in the crop plants (eg. vines) it is the Horn silica 501 which forms and sculpts this matter (Joly: 2007, p.87), working on the internal structure of plants, favouring their uprightness or verticality (more visibly erect vine shoots) and strengthening the outer cell walls (epidermis) of vine leaves and grapes (Pierre Masson: 2014, p.45). Whereas Horn manure 500 drives a sense of place or ‘terroir’ into the wine, it is Horn silica 501 which ensures this sense of place tastes ripe.

Also known as | French: La silice de corne or la 501. | German: Das Hornkiesel-Präparat. | Italian: il cornosilice or il preparato 501 or Il 501. | Portuguese: chífre silica. | Spanish: preparación de sílice en cuerno or preparado 501.


The Economist., ‘The chips are down’, December 1st 2018, p.20-22.

Christian von Wistinghausen,. Scheibe, Wolfgang., von Wistinghausen, Eckard., and König, Uli., The biodynamic spray and compost preparations production methods Booklet 1 (Biodynamic Agricultural Association UK, 2000), p.24-25.

Monty Waldin., Biodynamic Gardening (Dorling Kindersley, 2015).

Monty Waldin., Biodynamic Wine (Infinite Ideas, 2016).

Nicolas Joly., What is Biodynamic Wine (Clairview, 2007) trans. by M. Barton, p.87.

Pierre Masson,. A Biodynamic Manual (2nd edition 2014, Floris), p.45

Richard Thornton Smith., ‘Soil and light as a focus for biodynamics’, Star & Furrow 123/2015, p.12.

Rudolf Steiner., Spiritual Foundations for the Renewal of Agriculture (Bio-Dynamic Farming & Gardening Association, Inc. USA, 1993) trans. by C. Creeger and M. Gardner, p.74