Biodynamic farming is an agricultural system that began with a series of lectures given by Rudolf Steiner in 1924, at the request of farmers worried about declining soil and seed quality. It layers two distinctive things on top of what we would now call organic practice: nine numbered preparations applied in tiny quantities, and a sowing calendar keyed to the moon's position in the zodiac.
It is also the reason a bottle of wine might carry a Demeter mark. Roughly a fifth of the world's certified biodynamic land is vineyard, which is why most people meet this system through wine rather than vegetables.
Three parts, worth separating
Almost all of the confusion around biodynamics comes from these being discussed as one thing.
| Part | What it is | Evidence |
|---|---|---|
| Organic core | Composting, rotation, cover crops, livestock integration, no synthetic inputs | Well supported |
| The preparations | Nine numbered field and compost preparations, 500–508 | Compost effects plausible; specific mechanism unsupported |
| The sowing calendar | Root, leaf, flower and fruit days by lunar zodiac position | Not reproduced under controlled conditions |
Biodynamic farms often do perform well against conventional ones in long-term soil trials — better soil structure, more organic matter, more microbial activity. Those results are real. But comparisons that also include ordinary organic farming generally find the gains come from the organic practices, not from the preparations or the lunar timing.
The sowing calendar
This is the part that brings people here from moon questions. It was developed by Maria Thun, a German researcher who ran sowing trials from the 1950s onward and published an annual calendar that is still produced today.
The system tracks which zodiac constellation the moon is passing through, and groups the signs by classical element. Each element governs a plant part:
- Earth signs — root days. Sow and tend carrots, potatoes, beets, onions.
- Water signs — leaf days. Lettuce, cabbage, herbs, anything harvested for foliage.
- Air signs — flower days. Broccoli, cut flowers, anything harvested in bloom.
- Fire signs — fruit and seed days. Tomatoes, beans, squash, grain.
The moon passes through a sign in roughly two and a half days, so the character of the day changes every couple of days on a repeating cycle.
This is a different system from the more familiar moon planting calendar, which tracks the phase — waxing for above-ground crops, waning for roots. The two overlap and periodically contradict each other, which tells you something useful about how each was assembled. Both are covered in the moon and agriculture.
The preparations
Nine preparations, numbered 500 to 508, applied in very small amounts.
- 500 — horn manure. Cow manure packed into a cow horn, buried over winter, then stirred into water and sprayed on soil.
- 501 — horn silica. Ground quartz, same burial method, sprayed on foliage.
- 502–507 — compost preparations. Yarrow, chamomile, stinging nettle, oak bark, dandelion and valerian, each fermented in a particular way and added to compost heaps in tiny quantities.
- 508 — horsetail. Brewed as a tea and used against fungal problems.
The quantities involved are genuinely minute — a preparation may be spread across many hectares. The claimed mechanism is not nutritional, and it does not correspond to anything in established soil science. Where trials find compost quality improves, the plausible explanation is ordinary microbial inoculation rather than the specific ritual of preparation.
Where it came from
Steiner delivered the founding lectures in 1924, the year before his death, at the estate of a farmer in what is now Poland. He was not an agricultural scientist; the lectures were part of his broader anthroposophical philosophy, and the farming system carries that framework with it, including cosmic influences on plant growth.
The Demeter certification body followed in 1928 and now operates internationally. It is worth knowing that the system arrived essentially complete, from a philosophical framework, rather than being assembled from field results. Maria Thun's later trial work sits on top of an already-finished structure.
So why does it seem to work?
Because a substantial part of it does — just not the distinctive part.
- The organic core is genuinely good farming. Composting, rotation and reduced inputs improve soil over time, and biodynamic farms tend to do them thoroughly.
- Closed-loop practice pushes further than most. Biodynamic standards ask farms to produce their own fertility rather than importing it, which is demanding and tends to produce careful farmers.
- The calendar enforces attention. A grower following a sowing calendar is in the field on a fixed rhythm, staggering plantings and observing closely. That is an agronomic advantage produced by the schedule rather than by the moon.
- Selection effect. People who commit to a demanding certification are not average growers, and the farms are not average farms.
If you want the soil benefits, the organic practices are what deliver them and they are available without the rest. If you want the calendar as a working rhythm, it is a perfectly good one — just not for the stated reason. And if you enjoy the whole framework as a way of relating to a piece of land, that is a legitimate thing to want, and it does not need to be scientifically true to be worth doing.
The cycle as a working rhythm
An eBook, audiobook and printable workbook for one complete lunar cycle — a phase-by-phase structure you can run against a garden, a project, or a season.
Explore Lunar FlowCommon questions
What is biodynamic farming?
An agricultural system originating in a 1924 lecture series by Rudolf Steiner. It combines organic practices such as composting, crop rotation and integrating livestock with two distinctive elements: nine numbered field and compost preparations, and a sowing calendar based on the moon's position in the zodiac.
What is the biodynamic sowing calendar?
A planting calendar developed by Maria Thun from the 1950s. It assigns each day a root, leaf, flower or fruit character based on which zodiac constellation the moon is passing through, grouped by classical element — earth for roots, water for leaves, air for flowers, fire for fruit and seed.
Is biodynamic farming the same as organic?
It overlaps heavily but is not identical. Biodynamic farms meet organic standards and generally go further on closed-loop farming and biodiversity. What is unique to biodynamics is the preparations and the lunar calendar, neither of which is part of organic certification.
Does the biodynamic sowing calendar actually improve yields?
Attempts to reproduce lunar sowing effects under controlled conditions have generally not found a consistent yield advantage. Where biodynamic farms outperform conventional ones in trials, the improvements are largely attributable to the organic practices — compost, rotation, reduced inputs — rather than to the preparations or the calendar.
What are the biodynamic preparations?
Nine numbered preparations, 500 to 508. Two are field sprays — horn manure and horn silica — and six are used in compost, made from yarrow, chamomile, nettle, oak bark, dandelion and valerian. The ninth, horsetail, is used against fungal problems. They are applied in very small quantities.
What is Demeter certification?
Demeter is the certification mark for biodynamic produce, established in 1928 and now operating internationally. It is the label you are most likely to have encountered on biodynamic wine. Certification requires organic standards plus the biodynamic-specific practices.
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