BD 508 Horsetail: Foliar and Soil Spray Guide
What Is BD 508?
BD 508 is made from Equisetum arvense, a plant commonly known as horsetail. JPI’s current directions distinguish fresh tea for foliage from fermented tea for soil. The standard compost-preparation set is BD 502–507; historical uses of horsetail in compost are discussed in the cited archive.
Hugh Courtney recalled that interest in this preparation had once declined:
When I began distributing the preparations following Josephine Porter’s death in 1984, I was troubled by the fact that two of the preparations... seemed to be of virtually no interest to anyone ordering preparations. Those two were BD 501... and BD 508, Equisetum arvense or horsetail herb.
– Hugh J. Courtney, Applied Biodynamics, no. 68 (2010): 1.¹
Biodynamic growers use horsetail in moisture-prone conditions alongside airflow, water management, and close observation. Follow the current BD 508 instructions for the preparation and application method.
How to Prepare and Apply BD 508
JPI provides two distinct methods. Fresh tea is cooled, strained, diluted, stirred, and applied as a fine mist to foliage. Fermented tea is prepared separately, fermented for 10–14 days, then diluted at one part concentrate to nine parts water for soil application. Both methods require 20 minutes of vigorous stirring after dilution. See the full quantities, coverage, and application directions. The historical passage below describes the fermented method:
Take one unit of shredded Equisetum arvense ... Bring to a boil in one gallon of water and simmer for one hour... allow to ferment ten to fourteen days ... One unit of horsetail can thereby treat up to three acres with as powerful effect as can be achieved by the fresh tea recipe on only one acre.
– [Attributed to Hugh J. Courtney], Applied Biodynamics, no. 68 (2010): 5.²
Choose the dried horsetail herb or fermented concentrate that matches the method you intend to use. A fresh foliar tea and a fermented soil spray have different preparation steps and coverage; do not interchange their dilution instructions. Calendar timing in the historical material is part of biodynamic practice and should be considered alongside local weather and plant condition.
The Spiritual Science of BD 508
In biodynamic tradition, BD 508 is associated with the moon and water processes in soil and plants. Hugh Courtney linked it directly to the sensory system of the farm organism:
It is BD 501, and especially BD 508 (by virtue of its ‘normalization’ of the moon’s earthly energies), that stimulates the sense organs of the farm individuality... Without that stimulation... the other members of the solar system cannot bring to bear their powers...
– Hugh J. Courtney, “Revealing the Hidden Forces of Equisetum arvense,” Applied Biodynamics, no. 68 (2010): 9.³
Within this spiritual framework, BD 508 is understood as restoring the farm’s receptivity to lunar, solar, and planetary influences. These descriptions convey the biodynamic interpretation preserved in Courtney’s writing.
📚 Footnotes
- Hugh J. Courtney, “Revealing the Hidden Forces of Equisetum arvense,” Applied Biodynamics, no. 68 (2010): 1.
-
Ibid., 5.
-
Ibid., 204.
Frequently asked questions
What is BD 508 horsetail, and is it a compost preparation?
BD 508 is made from Equisetum arvense (horsetail) and prepared as a fresh-tea foliar spray or a fermented-tea soil spray. BD 502–507 are placed separately in compost, giving each preparation a clear role in biodynamic practice.
Why do biodynamic growers use BD 508?
JPI’s biodynamic guidance uses horsetail in moisture-prone conditions as part of preventive fungal management. It complements airflow, moisture management, and close plant observation in an integrated approach to healthy growing conditions.
How do I prepare and apply BD 508?
Use fresh tea for a foliar mist or fermented tea for a soil spray. Both JPI methods require 20 minutes of vigorous stirring after dilution. The fermented method uses one part concentrate to nine parts water. Follow the current BD 508 instructions for the full quantities, preparation steps, and coverage.
How does BD 508 relate to lunar rhythms in biodynamic practice?
Hugh Courtney described BD 508 in relation to the moon and water processes within a biodynamic framework. Growers can explore this traditional relationship through dated applications and observation while also tracking local weather, plant condition, and the current JPI method.
What habitat does common horsetail favor?
Common horsetail often grows in open places with moist subsoil. It can tolerate strong sun and a drier-looking surface when its underground rhizomes reach a steady water supply below.
For BD 508, are green horsetail shoots used or the brown spring shoots?
BD 508 uses the green above-ground shoots of common horsetail (Equisetum arvense). The brown spring shoots bear spores and represent a different growth stage of the plant.
How does common horsetail reproduce?
Common horsetail (Equisetum arvense) reproduces through spores and spreads through underground rhizomes. Its brown fertile shoots bear spores, while the green branching shoots provide the plant material used for BD 508.
Use this preparation: Shop BD 508 Horsetail · BD 508 application instructions