Horn Silica (BD 501) | Instructions for Use on Foliage

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One unit is 1 teaspoon.

One unit treats all applications up to one acre.

What you need:

  1. 3 gallons of lukewarm rainwater (or chemical free water) for every 1 unit of BD 501.
  2. A clean container large enough to prevent splashing out (chemical-free).
  3. A light-weight, but strong stick.

Directions:

Stir vigorously in one direction until liquid forms a deep crater. Quickly reverse direction and repeat. Continue this alteration every minute or so for one full hour. Use immediately.

Spraying:

  • Spray in the morning, just as the sun is touching the leaves.
  • Spray as soon as possible after stirring; it deteriorates rapidly if left standing. Pour mixture through a paint strainer, and then use an ordinary sprayer for a fine mist.
  • Spray on foliage, but it will do no harm to soil.
  • Cover one acre per unit.
  • Always use chemical-free, clean utensils.

Storage:

  • Keep in any dry or sunny place until used.
  • It keeps indefinitely if dry. Spray only on areas where 500 has been used previously.

When to use:

  • Only after plant roots are well established.
  • Use as early in the morning as possible.
  • Use when there is no wind.
  • Use with seedlings, when 2nd or 3rd leaves have unfolded.
  • Use only following blossoms on trees or shrubs, before leaf growth. Use on foliage emergencies—when diseases or pests have destroyed much foliage.
  • Usually in late spring or early summer when warm weather is well established.
  • Never when there is a danger of frost.
  • Never just before a rain.
  • Never before transplanting.
  • Never use on young evergreens and fruit trees. You can use when they are of bearing age.
  • Use especially during wet seasons with too little sunshine.
  • Use indoors or in greenhouses during the shortest days of the year.

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Can horns used for BD 501 Horn Silica be reused?

Yes. Horns used for BD 501 can be reused rather than discarded after one use. Keep horns reserved for BD 501 separate from those used for BD 500; preparation makers have reused sound horns for several years. (Ueli Hurter, Biodynamic Preparations around the World, p. 253.)

How long can a BD 501 horn be reused?

Reuse a sound BD 501 horn while it remains in good condition, reserving it for BD 501 rather than switching it to BD 500. One Indian preparation-making account reports four or five years of use in the Himalayas and about three uses in hotter regions; actual service life follows the horn’s condition and local setting. (Biodynamic Preparations around the World, p. 324.)