Why Water-Soluble Calcium?
Calcium is an essential nutrient for your plants, especially flowering plants like tomatoes, peppers, and roses. A lack of calcium can cause problems such as blossom end rot in tomatoes, stunted growth, and weak stems. To prevent these issues, it’s crucial to provide calcium in a form that plants can readily absorb.
Eggshells are a well-known source of calcium. Many gardeners crush eggshells and either add them to compost or sprinkle them directly onto the soil. While this method does release calcium, it takes a long time for the calcium to become available to plants.
If plants need calcium sooner, there is a better approach: Water-Soluble Calcium (WSCa).
What Is Water-Soluble Calcium (WSCa)?
Water-Soluble Calcium (WSCa) is a liquid calcium solution made by reacting eggshells with vinegar. This reaction breaks down calcium carbonate (CaCO₃) into calcium acetate, which plants can easily absorb. The resulting solution can be applied as a foliar spray or directly into the soil for quick uptake. In addition to being fast-acting, it is cost-effective and easy to make at home.
Let’s dive into the process!
How to Make Water-Soluble Calcium
Ingredients
- Eggshells
- Vinegar (white or apple cider vinegar)
- Glass container
- Measuring cup (optional)
Steps
- Collect the Eggshells – Store eggshells in a ziplock bag and keep them in the freezer until you have enough.
- Prepare the Eggshells – Wash and dry the eggshells. You can sun-dry them or heat them in the oven for faster drying.
- Crush the Eggshells – Grind the eggshells into a fine powder using a blender or mortar and pestle.
- Add Vinegar – Transfer the powdered eggshells into a glass jar. Ensure the jar is large enough to accommodate the reaction, as bubbling can cause overflow (don’t say I didn’t warn you!). It’s best to work in batches. Pour vinegar over the eggshell powder, making sure the powder is completely covered. A general guideline is a 1:10 ratio of eggshells to vinegar (e.g., 100g of eggshells to 1L of vinegar).
- Fermentation – Let the mixture sit in a loosely covered jar for 5-7 days. Bubbling indicates the reaction is still occurring. Do not seal the jar tightly, as gases need to escape, but also avoid leaving it open to prevent contamination.
- Strain and Store – Once the bubbling stops, strain the liquid and store it in a sealed container.
How to Use Water-Soluble Calcium
Dilution: Mix 1 tablespoon of WSCa per liter of water.
Application:
- Foliar spray for fast absorption (apply in the evening).
- Soil drench to support root uptake.
- Ideal for tomatoes, peppers, and fruiting plants.
Final Tips & Warnings
- Do not overapply; too much calcium can cause nutrient lockout.
- Use in combination with other natural fertilisers for balanced nutrition.
- Test on a small area before widespread use.
By making WSCa at home, you provide your plants with a fast-acting, eco-friendly calcium source while repurposing kitchen waste. Give it a try, and your plants will thank you!