At a Glance:
One unit is one teaspoon.
One unit treats one acre.
What it does:
BD 501 is a stirred, early-morning quartz foliar preparation traditionally paired with soil-directed BD 500. Biodynamic growers use it to support foliage, light response, and ripening. Controlled studies with plant-available silicon have measured higher photosynthesis, while BD 501 vineyard trials have measured promising leaf and yield responses.
How to use:
- In the early morning, stir one unit for one full hour in 3 gallons of lukewarm rainwater or other chemical-free water.
- Spray immediately as a fine mist on foliage, just as the sun is touching the leaves.
- Use only after BD 500 has previously been applied and plant roots are well established.
- One unit treats all applications up to one acre.
Variations:
501: Silica, quartz
501f: Silica, feldspar
501g: Silica, quartz plus homeopathic 24k gold
☀️ Learn More about BD 501 Horn Silica
Product Details:
BD 501 should be used after BD 500. A minimum of one unit of 501 should be used per acre per year, unless specific conditions indicate otherwise.
Plant-available silicon has enhanced measured photosynthesis: a foliar silicon wheat study and a field-grown bean study recorded higher leaf photosynthetic rates under water stress. For BD 501 itself, a two-year Cesanese grapevine trial found higher later-stage leaf polyphenols and chitinase activity. A separate two-season Semillon and Cabernet-Sauvignon trial found higher petiole silicon in one BD 501 treatment and generally higher yields with biodynamic-silica and potassium-silicate sprays than with water controls. In a five-year vineyard comparison, the program using BD 500 and BD 501 together showed higher photosynthesis at one sampling. These studies identify the preparation or silicon form tested and give growers specific plant responses to observe.
BD 501f (feldspar)
501f uses feldspar rather than quartz. In JPI's 1995 discussion, Hugh Courtney proposed comparing feldspar on sandier soils with quartz on heavier soils. The two mineral variations offer a way to observe how plants respond under local soil and growing conditions.
BD 501g (gold)
501g combines JPI's quartz horn silica with a homeopathically prepared 24k-gold component. Biodynamic tradition associates gold with the sun and ripening. Apply this variation following the standard BD 501 directions.
BD 501 Detailed Usage Instructions: English | Spanish | Chinese
Additional Article: Brief Instructions: 500, 501, 508
Please note: Quantities over 1 may be bagged together.
