Structure — Water-Soluble Calcium Phosphate

What is Structure?

Structure is water-soluble calcium phosphate made by dissolving charred bones in natural vinegar. The acid dissolves the calcium and phosphorus from the bone, creating a bioavailable mineral solution that plants can absorb directly.

What does it do?

Structure builds the physical architecture of the plant — thicker cell walls, stronger stems, deeper root development. Plants with adequate calcium are firmer, more upright, and more resistant to pests and disease. Many problems that appear biological are actually structural: a calcium-deficient plant is simply more vulnerable.

How is it made?

Char bones over low heat until no fat or meat is left. Big ocean-fish bones are best; beef or pork bones work too (not bird bones). Use them whole or crush them lightly. Powdered bone char works as well, but it foams fast, so pour it in slowly, as Master Cho did in 2017. Cover with vinegar at 1 part bone to 10 parts vinegar, as Master Cho did. Leave it about 7 days, until it stops bubbling. Strain; the golden liquid is Structure. Use at 1:1000 (about 4 ml per gallon), sprayed on the underside of the leaves.

When to use it

In Master Cho's chart, Structure is in every stage from seed to fruit, and it matters most at the changeover to flowering. It leaves the mix only in the last two weeks before harvest. Leave it out for a small plant you need to push into leaf, and use it stronger in long rain.