# Biodynamic Horn Silica Preparation (BD 501) — Spray Preparation

## At a Glance:

### One unit is one teaspoon.  
One unit treats one acre.

**What it does:**  
Enhances photosynthesis and strengthens plant structure. Brings clarity, light, and ripening forces into the plant. Particularly helpful for fruiting, flowering, and flavor.

**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](https://go.jpibd.org/guide-bd-501 "BD501 Horn Silica: Bringing Light into Leaf and Flower")

## 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.

Horn silica stimulates photosynthesis and the ripening process, regulates leaf growth, enhances flavor and storage quality. It also improves carbon sequestration by enhancing the sugar-forming process.  

##### BD 501f (feldspar)

Hugh Courtney postulates that, while horn silica 501 made from quartz rock crystal may be most effective for those on mainly heavy clay soils, those on sandier soils might benefit from using a form of horn silica 501 with a stronger relationship to the lime end of the lime/silica polarity. In this case orthoclase or feldspar with their constituents of calcium or related elements—feldspar being principally aluminum silicates of potassium, sodium and calcium—would be used. – [Monty Waldin](https://chateaumonty.com/horn-silica-501/)

##### BD 501g (gold)

Horn silica (501g) stimulates photosynthesis and the ripening process, regulates leaf growth, enhances flavor and storage quality. Our gold-potentized version of 501 contains 24k gold that has been potentized homeopathically. Homeopathic gold brings more of the influence of the alchemical sun to bear in the garden, bringing more light into the garden, enhancing ripening.  
  
In some biodynamic experiments, gold-potentized water seems to mitigate the negative influence of solar eclipses. We recommend 501g for bringing more of the balanced solar influence into play when there are inauspicious astronomical aspects in the sky (such as blackout times), especially inauspicious times in relation to the sun. It is generally advisable to stir before a blackout time.

When seeds are treated with gold-potentized water and germinated during a solar eclipse, they do not show the same deleterious effects as other seeds without the enhancement with gold.

When the sun is obscured in the sky, we can bring its influence into play by introducing gold between the plant and the obscuring constellation.

* * *

**BD 501 Detailed Usage Instructions: [English](https://go.jpibd.org/instructions-bd-501) | [Spanish](/pages/making-using-bd-preps#spanish501) | [Chinese](/pages/making-using-bd-preps#chinese501)**

**Additional Article:** **[Brief Instructions: 500, 501, 508](https://cdn.shopify.com/s/files/1/0017/4473/2221/files/500_501_508_Brief_Instructions.pdf?337)**

**Please note: Quantities over 1 may be bagged together.**

## Details

- **Price:** 4.81 USD
- **Vendor:** The Josephine Porter Institute
- **Type:** Spray Preparations
- **Tags:** farming, gardening, orcharding, Spray Preparations, vineyard

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| 501 Horn Silica (quartz) | 4.81 USD | In stock |
| 501f Horn Silica (feldspar) | 4.81 USD | In stock |
| 501g Horn Silica (gold) | 4.81 USD | In stock |

## Images

- Biodynamic Horn Silica Preparation (BD #501) BD Spray Preparation - The Josephine Porter Institute
- Biodynamic Horn Silica Preparation (BD #501) BD Spray Preparation - The Josephine Porter Institute
- Biodynamic Horn Silica Preparation (BD #501) BD Spray Preparation - The Josephine Porter Institute

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> Source: [The Josephine Porter Institute](https://www.jpibiodynamics.org/products/horn-silica-spray-preparation-bd501)
> Updated: 2026-08-10