Horn silica (501)
The light preparation — for ripening and expression.
Horn silica (preparation 501) is the “light” counterpart of 500. Ground quartz is fermented in a horn over summer and then dynamised and sprayed as a very fine mist over the canopy.
It is used to reinforce light metabolism, photosynthesis and ripening, and practitioners associate it with aromatic definition and clarity in the wine. It is applied early in the morning, typically on fruit/flower days, sparingly to avoid over-exposure.
Effort
Medium — occasional applications in the ripening phase.
Cost
Low — minimal quantities.
Time to result
Within the season, in ripening and tasting.
What it advances
Contribution by goal — click through for detail and metrics.
It is the preparation used to reinforce light metabolism and photosynthesis, supporting ripening and canopy health.
Practitioners associate 501 with aromatic definition and clarity in the wine — the preparation most tied to expression.
501 is one of the preparations Demeter requires; its application must be documented.
How it works
Dynamised in water and sprayed as a fine, upward mist over the canopy, it is used to reinforce photosynthesis and ripening.
How to apply
- 1Dynamise in water for an hour at dawn.
- 2Spray as a fine mist over the canopy early in the morning.
- 3Apply sparingly, on fruit/flower days.
- 4Log rate, plot and date.
What to measure
Frequently asked
Can 501 cause sunburn?
Applied in excess or in intense heat, the boost in light activity can worsen stress. That is why it is applied sparingly and early in the morning.
When is 501 applied?
Mostly in the ripening phase, early in the morning and on fruit/flower days, to support photosynthesis and fruit definition.
Related reading
Related practices
How GrapeFlow helps
Plan and document this practice by plot, with an audit-ready history for Demeter certification.
Biodynamic calendar
Root, leaf, flower and fruit days and the lunar phases in GrapeFlow, to plan preparation applications and work in step with the calendar.
Preparations & application log
Every application of 500, 501 and the other preparations logged by plot, date and rate — the history the Demeter audit asks for.
Tasting notes & analyses
Per-lot tastings and analyses over time, to relate the biodynamic programme to how the wine evolves.