Root, Leaf, Flower, Fruit: The Biodynamic Sowing Calendar

The biodynamic sowing calendar sorts every day of the month into one of four kinds, root, leaf, flower or fruit, based on which of the twelve zodiac constellations the moon is passing in front of that day. Each kind of day is matched to the part of the plant a grower wants to encourage: root days for carrots and beetroot, leaf days for lettuce and spinach, flower days for chamomile and cut flowers, fruit days for tomatoes and grain. The calendar was developed by the German researcher Maria Thun from decades of trials on her own farm, and it remains the most widely used biodynamic planning tool, published every year as a dated almanac.

What are the four kinds of day?

Each of the twelve zodiac constellations the moon moves through in its roughly monthly orbit is grouped, in the practice, under one of four classical elements, and each element is tied to one part of the plant. Earth constellations, Taurus, Virgo and Capricorn, give root days, best for root crops and for any work on root growth. Water constellations, Cancer, Scorpio and Pisces, give leaf days, favoured for leafy vegetables and for anything where leaf growth is the goal. Air constellations, Gemini, Libra and Aquarius, give flower days, used for flowering ornamentals and for crops grown for their blossom. Fire constellations, Aries, Leo and Sagittarius, give fruit days, used for fruiting and seed crops such as tomatoes, squash and cereals.

Where does the calendar come from?

Maria Thun began her observations on sowing and the moon in the 1950s, testing the same crops, mainly radishes in her early trials, under different lunar positions over many years on her farm in Hesse, Germany. One of her recorded findings concerned soil cultivation rather than sowing: working ground while the moon passed in front of Leo produced heavy weed germination, while working the same ground under Capricorn produced far less. From results like these she built a yearly calendar assigning a root, leaf, flower or fruit character to each day, which she and her collaborators continued to publish and refine until her death in 2012. Her calendar is still issued annually, now under several publishers, and remains the standard reference for the method in the German-speaking world and beyond.

How is the calendar actually used?

A grower who follows the calendar picks the day type that matches the task at hand rather than the crop's common name alone. Sowing carrot seed is timed to a root day. Pricking out lettuce seedlings is timed to a leaf day. Cutting chamomile flowers for drying, the same chamomile used in biodynamic preparation 503, is timed to a flower day. Harvesting tomatoes or saving seed from a fruiting crop is timed to a fruit day. The calendar also marks ascending and descending phases of the moon's path and occasional node and eclipse periods that the practice treats as unfavourable for any sowing at all, which growers using the calendar close to its letter will avoid.

Does the calendar replace ordinary growing knowledge?

No, and the practice itself does not present it that way. The calendar is a timing layer laid over the decisions a grower already has to make about soil, rotation, compost and climate. A root day does not fix poor soil structure, and a fruit day does not ripen a tomato planted too late in a cold climate. Growers who use the calendar generally treat it as one more variable to align, alongside frost dates, soil temperature and the preparations already active in the compost and the field, not as a substitute for any of them.

Why does this calendar matter to a holding already running the preparations?

A holding that burns horn manure in winter and horn silica in summer, and that times its compost preparations to the season each plant is gathered in, is already working to a set of fixed points through the year. The sowing calendar is the same habit extended to the day-to-day work of the garden itself: deciding not just which season a job belongs to, but which day within that season. The four categories, root, leaf, flower and fruit, give a name to a distinction most gardeners already make informally, that a crop grown for its root behaves differently from a crop grown for its fruit, and that the two are not necessarily helped by the same conditions on the same day.

What does a grower need to start using it?

An annual biodynamic planting calendar, available as a dated almanac from several biodynamic publishers, and a willingness to check the day type before sowing rather than after. Beyond that, nothing changes about how the seed is sown, the bed prepared or the water given. The calendar decides when a task belongs on the list; it does not do the task itself, and the growers who have used it longest tend to describe it the same way, as a rhythm kept alongside the rest of the work, not a replacement for any part of it.