Biodynamic preparations: how and when to apply 500, 501 and the compost preps

Biodynamic viticulture runs on a compact toolkit of nine preparations, numbered 500 to 508. They are not fertilisers or fungicides in the conventional sense — they are applied in tiny quantities to steer the life of the soil and the vine. For a working grower, two of them set the rhythm of the whole year: horn manure (500) and horn silica (501). This is a practical guide to what each preparation does, how to prepare and spray it, and when the biodynamic calendar says the moment is right.

It ends with the least romantic part — keeping the record straight. Because whatever your view on the cosmology, Demeter certification is, in the end, an audit of what you applied, where, and when.

The nine preparations at a glance

They fall into three groups:

• The two field sprays — 500 (horn manure) and 501 (horn silica) — applied directly to the soil and the canopy.
• The six compost preparations — 502 to 507 (yarrow, chamomile, stinging nettle, oak bark, dandelion, valerian) — inserted into compost and manure to guide how it breaks down.
• Horsetail (508), a plant decoction used against fungal pressure.

500 — horn manure: waking up the soil

Horn manure is cow manure packed into a cow horn and buried over winter, where it transforms into a dark, humus-like, earthy-smelling material. It is the soil preparation: it stimulates rooting, microbial life and humus formation.

• Dynamize: stir roughly 100–300 g in 30–35 litres of water per hectare for a full hour (see below).
• Spray onto the soil in large droplets — you want it to reach the ground, not the leaves.
• Time it for late afternoon or evening, on a descending Moon, when the tradition says the forces are drawing down into the earth.
• Applied a few times a year — classically in autumn and again in spring, and at planting.

501 — horn silica: light and ripening

Horn silica is finely ground quartz packed into a horn and buried over summer. It works with light — photosynthesis, upright growth, aroma and ripening. It is the counterpart to 500: where 500 works downward into the soil, 501 works upward into the plant.

• Dynamize a very small amount — on the order of 1–4 g per hectare — stirred in water for an hour, the same vortex-and-chaos as 500.
• Spray as a fine mist over the canopy, early in the morning, so it settles on the leaves in the rising light.
• Time it for an ascending Moon and, on a fruit crop like the vine, ideally a fruit day; a light-and-warmth spray makes least sense in overcast, humid weather.
• Applied at key moments — after fruit set and around veraison — to support even ripening. Use it sparingly: too much 501 can over-stress the vine.

502–507 — the compost preparations

These six are not sprayed on the vineyard on a lunar schedule. They are inserted, in tiny amounts, into compost heaps and manure to organise decomposition and concentrate the compost’s effect on the soil. Each is linked to a plant and, traditionally, to a process:

• 502 — yarrow (Achillea): sulphur and potassium processes.
• 503 — chamomile (Matricaria): calcium and nitrogen stabilisation.
• 504 — stinging nettle (Urtica): iron, and a general “sensitising” of the compost.
• 505 — oak bark (Quercus): calcium, and resistance to fungal disease.
• 506 — dandelion (Taraxacum): the silica–potassium relationship.
• 507 — valerian (Valeriana): the phosphorus process; often sprayed over the finished heap as a warm “skin”.

In practice they go into the heap together, in autumn, as the compost is built — here the season, not the lunar day, is what matters most.

508 — horsetail (Equisetum arvense)

Horsetail is prepared as a decoction or fermented tea and sprayed to reduce fungal pressure — downy and powdery mildew, rots. It is silica-rich and, biodynamically, used preventively to strengthen the plant and “dry” damp, fungal tendencies, rather than as a curative fungicide. Its real trigger is disease pressure and the weather, so it does not follow the strict lunar timing of 500 and 501; when it is timed, growers favour a descending Moon and the afternoon.

Timing: the calendar is the other half of the work

The preparations and the biodynamic calendar are inseparable. The calendar assigns each day an element and a plant part — root (earth), leaf (water), flower (air), fruit (heat) — and overlays the direction of the Moon (ascending vs descending) and the lunar nodes, the classic “do not intervene” days. For the field sprays, the direction of the Moon is the primary signal:

• 500 → descending Moon, late afternoon: forces drawing down toward soil and root.
• 501 → ascending Moon, early morning: forces rising up into the plant.
• Both → avoid lunar-node days, and postpone if disease pressure or the weather forces your hand — the vine comes first.

Intellectual honesty: the scientific evidence for a lunar-calendar effect on wine quality is limited and debated. The strongest, most agreed-on value is the discipline the calendar imposes and the record it produces — which is exactly what a Demeter audit asks for.

Dynamization: the one technique to get right

Whatever you spray, how you stir it matters as much as when. Dynamization means stirring the preparation into water for a full hour: drive a deep vortex down to the bottom of the barrel, then break it into turbulent chaos and immediately build the vortex the other way. That alternation — order into chaos, again and again — is the point. Spray the water within a few hours, before it goes flat.

Registering it in GrapeFlow — and building your Demeter evidence

GrapeFlow now carries the biodynamic layer all the way to the vineyard. Turn on the biodynamic module (Settings → Alerts) and it stops being a paper calendar on the wall:

• Every day in the 14-day calendar is tagged Root / Leaf / Flower / Fruit, with the Moon phase, ascending/descending and the lunar-node “avoid” days.
• The app recommends which field spray suits today — 500, 501 or 508 — rated by the current lunar direction and day type, with the reason spelled out.
• Log a vineyard operation or a field observation against the block and its biodynamic day type is recorded automatically — the same chip already shown on cellar operations like racking and bottling.
• Every application stays tied to the block (and, in the cellar, the lot), with its real field date — the traceable trail from vineyard to bottle.

Demeter certification does not ask you to prove the cosmology — it asks for records: which preparation, on which parcel, on what date, in what conditions. Keeping that trail in one place, tied to the block and dated, turns the annual audit from a scramble through notebooks into an export.

This is a practical overview, not a certification manual. Always follow the current Demeter / biodynamic standard, your certifier’s requirements and your preparation supplier’s instructions for quantities, storage and application.