Sprinkling eggshells on plants for calcium is a common practice. Seasoned gardeners and farmers know that the effect is not immediate as it takes many weeks or even months for the calcium to be released from the shell.
Think structure, when you think of calcium. Just as it works in humans, calcium is important to plant growth by aiding in smooth cell division and the formation of cell membranes. Plants with weakened root systems are low in this essential mineral. This is often marked by falling leaves. If you grow legumes, a deficiency shows up as empty pods. Calcium for chickens and animals is also important.
Korean Natural Farming (KNF) solves this slow release issue by dissolving properly prepared eggshells into a soluble state using fermented vinegar. Crab and oyster shells work well for this too.
Has your egg production decreased? Read this article for information on how to get your chicks laying again.
For reference, this water-soluble calcium is typically abbreviated WCA or WSC.
How Water Soluable Calcium Benefits Your Plants
- aids in utilization of carbohydrates and protein
- is crucial to cell membrane formation and smooth cell division
- helps convert vegetative growth to the reproductive stage (blossoming)
- prevents crop overgrowth
- strengthens flower buds — a concern, if they seem to be falling off for no reason
- hardens fruit
- prolongs storage period
- promotes absorption of phosphoric acid

Making WCA is super simple. The most time-consuming part is the first step – removing the inner membrane from the eggshells. I suggest using this recipe with a half gallon mason jar the first time around. You can do a quart, if you’re skeptical and don’t want to shell out (no pun intended) for the extra vinegar 😉
Even so, the only thing that is exact are the ratios. Any leftovers of the original ingredients can be saved for your next batch. As a general rule, minerals don’t degrade like vitamins. They are transferred from one medium to another.
Ingredients for Water Soluable Calcium for Chickens, Plants, & Animals
- one dozen egg shells (you probably won’t need all of it)
- brown rice vinegar (other fermented vinegars such as apple, pineapple and banana appear to work equally well)
Instructions
- Remove inner membrane from all the shells.
- Break shells into small pieces.
- Lightly roast the shells in a frying pan until brown. Do this slowly over the course of about 45 min, stirring frequently. Do not char them until black. You simply want to remove the organic substances that could rot the entire batch.
- Put 1 part of the crushed eggshells to 10 parts brown rice vinegar into a clean, half gallon-sized mason jar, but only fill 2/3 of it.
- Cover with paper towel or other breathable cloth or paper tied with string. You can use rubber bands, of course, but I’ve occasionally had some pop while I wasn’t looking. It will be bubbly and active at first like soda. After about a week or so, when it stops moving.
- To confirm the brew is ready, add a little of your extra toasted eggshell. If it does not produce new bubbles, you can strain off the vinegar.
- Store in a cool dark place in bottles that are not tightly closed. It must breathe. Overly tightened bottles have been known to explode over time. You have been warned.
- Be sure to label what’s in the bottle, including the date of extraction and dilution ratio, which is 1:1000.
Water-soluble calcium percolates for about 7 days
What Does the Dilution Ratio Mean?
A rate of 1:1000 means for every liter (1000 ml) of water you only need 1 ml of WCA. Since one teaspoon is roughly 5 ml, that means for every gallon of water, you would add just shy of a teaspoon of WCA. One gallon of water feeds a 100 sq ft bed. A little goes a long way. More is NOT better.
Note that when I say ‘feed’ I mean we’re feeding the soil. We’re building up the resilience and balancing nutrients within the soil. KNF always focuses on soil first, mainly because the mouth of the plant is in the roots. This means that not only will your current crops benefit, but the next year’s crop yields will be higher too!

That said, these inputs do not harm plants, when applied directly to leaves. In the case of WCA, spraying it on leaves (diluted, of course) helps prevent overgrowth and make sweet, firm fruits by moving carbohydrates from leaves and branches to the fruit.
And that’s not all! WCA is quite useful as a supplement for livestock and yourself (if you can get past the smell)! It may help animals and children who fail to thrive.

Used together with Water-Soluble Calcium Phosphate (WCP), it is helpful for chickens that have stopped laying or lost their feathers after a few years. This combo taken before pregnancy may also help stave off morning sickness.
I cannot emphasize enough how important it is to know how to make your own plant nutrients wherever you live. This is particularly important for the upcoming years as prices for unsustainably produced fossil-derived inputs and so-called ‘organic’ fertilizers skyrocket.
Do you make your calcium garden inputs? How’s it going for you? Let us know in the comments below!
Homemade Water Soluble Calcium for Chickens, Animals & Plants
Materials
- 12 egg shells
- brown rice vinegar (other fermented vinegars such as apple, pineapple and banana appear to work equally well)
Instructions
- Remove inner membrane from all the shells.
- Break shells into small pieces.
- Lightly roast the shells in a frying pan until brown. Do this slowly over the course of about 45 min, stirring frequently. Do not char them until black. You simply want to remove the organic substances that could rot the entire batch.
- Put1 part of the crushed eggshells to 10 parts brown rice vinegar into a clean,half gallon-sized mason jar, but only fill 2/3 of it.
- Cover with paper towel or other breathable cloth or paper tied with string. You can use rubber bands, of course, but I've occasionally had some pop while I wasn't looking. It will be bubbly and active at first like soda. After about a week or so, when it stops moving.
- To confirm the brew is ready, add a little of your extra toasted eggshell. If it does not produce new bubbles, you can strain off the vinegar.
- Store in a cool dark place in bottles that are not tightly closed. It must breathe. Overly tightened bottles have been known to explode over time. You have been warned.
- Be sure to label what's in the bottle, including the date of extraction and dilution ratio, which is 1:1000.
- Water-soluble calcium percolatesfor about 7 days
Notes
Love your chicks? Check out these great gift ideas for chickens.