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Biodynamic calendar
What it is
The biodynamic calendar is a gardening and farming calendar that sorts the days of the month by the part of the plant they are thought to favour: root, leaf, flower or fruit. It grew out of the biodynamic movement that followed Rudolf Steiner's agriculture lectures of 1924, and took its familiar form in the work of the German gardener Maria Thun (1922–2012), who published it every year from 1963 and whose family continues it. Many organic growers and a good number of vineyards use it.
It belongs to the wider practice of planting by the Moon, but it is a separate system with its own rules.
The four kinds of day
Each day takes the element of the constellation the Moon is passing in front of:
| Moon in a constellation of… | Day | Favours |
|---|---|---|
| Earth — Taurus, Virgo, Capricorn | Root | carrots, potatoes, onions, beetroot |
| Water — Cancer, Scorpio, Pisces | Leaf | lettuce, cabbage, spinach, herbs; the lawn |
| Air — Gemini, Libra, Aquarius | Flower | flowers, bulbs, broccoli |
| Fire — Aries, Leo, Sagittarius | Fruit | tomatoes, beans, squash, cereals, fruit trees |
Gardeners sow, tend and harvest each crop on its own kind of day. A wine maker following the calendar may prefer to taste on a fruit or flower day.
Constellations, not signs
The point most often missed is that the calendar follows the constellations — the real star groups along the ecliptic — and not the twelve equal 30° signs of the tropical zodiac used in most Western astrology, nor the equal signs of the sidereal zodiac. The constellations are of very unequal size: along the Moon's path Virgo spans more than 40°, Scorpius proper less than 10°, and the ecliptic also crosses Ophiuchus, which the calendar does not use as a sign. Because of precession, the constellations now sit roughly a sign behind the tropical signs of the same name. So when an ordinary Moon calendar says the Moon is in Gemini, a biodynamic calendar will often say she is in front of Taurus, and call it a root day.
The ascending and descending Moon
Thun also distinguished an ascending and a descending Moon. This is not the same as waxing and waning. Over about 27⅓ days the Moon's daily arc across the sky climbs higher, then sinks lower, following her declination from south to north and back. While she ascends — roughly as she moves from Sagittarius towards Gemini among the stars — sap is said to rise, and the calendar favours sowing and taking grafts. While she descends, from Gemini towards Sagittarius, it marks "planting time" for transplanting, pruning and spreading compost.
The calendars also mark short unfavourable spells, linked in Thun's published results to events such as the Moon's nodes, perigee and eclipses, when no sowing is advised. The details vary from one edition to another.
The evidence
Thun based the system on her own sowing trials over several decades and reported that the days made a visible difference. Others have been unable to confirm it: a long study by Hartmut Spiess in 1990 did not find the constellation effect, while a 2001 review by Nick Kollerstrom and Gerhard Staudenmaier, both sympathetic to the method, argued that a re-analysis supported it. The question is unsettled. As with every form of lunar gardening, weather, soil and season matter far more than the day of the calendar.
In the almanac
The Almanac's Moon panel offers biodynamic days as a separate tick box from gardening by phase and by sign, and works them out from the Moon's constellation rather than from her tropical sign, so a "leaf day" there is never simply "the Moon in a water sign".