Water Soluble Calcium Acetate (WCA) and Water Soluble Calcium Phosphate (WCP) are simple vinegar extractions of charred eggshells (WCA) or animal bones (WCP) used to supply calcium and phosphorus to plants—especially during flowering and fruiting stages.
Calcium strengthens cell walls and prevents issues like blossom-end rot. Phosphorus supports flower and fruit formation.
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How to Make WCA/WCP
Traditionally developed by Master Cho, this simple recipe yields a powerful mineral extract that will keep your plants standing tall and proud and fruit from going mealy.
Ingredients
- Clean eggshells (for WCA) or animal bones (for WCP)
- Vinegar (brown rice vinegar is traditional, but any high quality vinegar will work)
Equipment Needed
- Non-metallic jar or container
- Breathable cover (e.g. paper towel or cheesecloth with rubber band)
Step-by-Step Instructions
- Clean and char
- Scrub bones to remove any residue. Cook them in a dry pan over a flame or in an oven until they are fully charred—blackened, brittle, and odorless.
- This removes organic material (cartilage and fat residue) and makes minerals more available.
- Allow to cool. For egg shells, simply cook in an oven at 350°F (175°C) for 30-60 minutes or until shell lining has browned significantly.
- Place in non-metal container
- Fill your container no more than one-third full with the charred material.
- Add vinegar
- Pour vinegar over the shells or bones until fully submerged.
- This should equal around 1 part crushed bones/egg shells/oyster shells to 10 parts vinegar by weight.
- E.g. for 10 grams crushed egg shells add 100 grams VIN.
- Leave at least 1/3 of the container empty—this is crucial because the mixture will bubble vigorously as the reaction releases CO₂.
- Let it extract
- Cover the container with a breathable lid (e.g., cloth + rubber band) and let it sit in a shaded place for 14 days and bubbling stops.
- Strain and store
- After extraction, strain out the solids and store the liquid in a sealed, labeled jar in a cool, dark place.
- It will last up to 1 year.
How to Use WCA/WCP
Use WCP as plants transition toward and start to develop flowers. Use WCA as plants enter Fruit Set, Development, and Ripening stages. Dilute 1:500 in water to apply to plant foliage (leaves and stems). Apply undiluted (or diluted if you’d like) directly to the soil (before plants go in the ground) or compost piles to integrate minerals for root uptake.
Get a printable recipe for WCA and WCP by accessing our Resource Library below!