Yarrow has a distinctive place in biodynamic composting. BD 502 is made from the blossoms of Achillea millefolium, traditionally packed into a stag bladder, hung through summer, and buried over winter. Growers place the finished preparation in a compost pile in small amounts as part of the BD 502–507 set.
Biodynamic founder Rudolf Steiner saw something deeply special in this plant:
“Yarrow is indeed a miraculous creation. No doubt every plant is so; but if you afterward look at any other plant, you will take it to heart all the more, what a marvel this yarrow is.” — Rudolf Steiner, quoted in Patricia Smith, Applied Biodynamics, no. 37 (2002), 69.¹
In biodynamic practice, BD 502 is associated with sulfur, potassium, and trace-element processes. A 27-year randomized field experiment compared soils receiving composted manure alone, composted manure prepared with yarrow alone, and composted manure prepared with all six compost preparations. The yarrow-only treatment had a distinct microbial substrate-use profile; its microbes showed higher respiratory use of several nitrogen-containing compounds. The researchers interpreted that pattern as an improvement in the nitrogen status of the soil microbial community.
To prepare BD 502, fresh yarrow flowers are harvested in early summer and carefully cleaned of coarse stem material. The stuffing of the bladder must be done delicately to preserve its integrity:
Our preference at JPI is to have virtually stem-free florets to use in stuffing the bladders. This is most important because the stiff coarse stems, if left attached when being stuffed into the sheath, can puncture the walls of the stag bladder.
– Patricia Smith, Applied Biodynamics, no. 37 (2002), 71.²
After the summer hanging period, the bladder is buried in fall and retrieved in spring. In biodynamic understanding, this seasonal process concentrates the yarrow preparation’s formative qualities for use in compost.
Steiner described yarrow through relationships to Venus and Mercury, using these celestial images to discuss sensitivity, healing, and metabolic balance. The stag bladder is the traditional vessel in which the flowers undergo their summer and winter preparation.
BD 502 is a tangible compost preparation and, within biodynamic thought, a carrier of formative forces. Hugh Courtney expressed that way of working with the preparations:
We must exert an effort to grasp what it is that lives in this preparation and how it exerts its influence. In other words, we must do our utmost to understand the preparations, ‘not as substances, but as forces.’
– Hugh J. Courtney, Applied Biodynamics, no. 37 (2002), 83.³
In this biodynamic view, BD 502 is an “alchemical organ” of the pile: an image for its place in the living process that transforms manure and plant material into compost.
What is BD 502 and how is it used in composting?
BD 502 is the finished yarrow-flower preparation used as one member of the BD 502–507 compost set. JPI places BD 502–506 separately in five holes about halfway down a newly built pile; see the full method. Ordinary yarrow can also enrich a compost pile as plant material, while carefully prepared BD 502 carries the preparation-specific biodynamic role.
Why is yarrow referred to as an 'alchemical organ' of compost?
“Alchemical organ” is a biodynamic image for prepared yarrow’s place in the living transformation of a compost pile. Alongside that traditional language, a 27-year field experiment measured a distinct soil-microbial substrate-use profile where the composted manure had been prepared with yarrow alone.
What are the benefits of using BD 502 in compost?
BD 502 brings prepared yarrow into JPI’s six-preparation compost practice. In a 27-year randomized field experiment, soil receiving composted manure prepared with yarrow alone showed a distinct microbial substrate-use profile and higher respiratory use of several nitrogen-containing compounds. The researchers interpreted this as improved nitrogen status in the soil microbial community. Add BD 502 with BD 503–507 to a properly built pile using JPI’s current instructions.
How should BD 502 be applied in a compost pile?
Place BD 502 in one of the five holes for BD 502–506, scattered across the pile and deep enough to put the preparation about halfway down. Close the hole with old compost or good soil; BD 507 is handled separately. Use JPI’s current full-set directions for amounts and pile conditions.
Where does yarrow tend to grow?
Yarrow grows in patchy pastures, roadsides, and dry, unfertilized sites. It may stay low on barren ground and grow much taller in a more fertile, partly shaded spot.
Why does my yarrow stay low and never flower?
Repeated mowing is one possible reason: it can keep yarrow in low rosettes without flowers. Let a patch grow without mowing if you want to see whether it produces flower heads for BD 502.
Can a local male deer bladder be used to make BD 502 yarrow?
Yes. The traditional vessel is a stag (male deer) bladder. In a documented U.S. case study, preparation-maker Devon Strong described black-tailed and mule deer as his local deer, reported that elk bladders were also sometimes used, and took care to use a male deer's bladder. This illustrates how growers adapt the yarrow-preparation method to locally available deer. Read the Agriculture Section case study.
Use this preparation: Shop BD 502 Yarrow · BD 502–507 compost instructions
