Easy Homemade Input for your Flower Farm: Eggshell Extract or WCA (2024)

Eggshell Extract or WCA

Last week I started a little blog series on easy homemade regenerative inputs for your farm by explaining what leaf mold tea – or “JMS” a la JADAM – is as well as how to make and use it. Leaf mold tea is great for boosting the amount of biological life (bacteria, protozoa, fungus, etc) in your soil and ultimately helping loosen it up if it has been compacted from tillage or has poor drainage. That’s what we refer to as a “biostimulant”. But leaf mold tea does not add any nutrition to your soil (i.e., minerals/fertilizer).

Today I want to introduce you to one of my favorite homemade regenerative inputs for adding a vital mineral nutrient to your soil: calcium extracted from eggshells. This input comes straight out of the Korean Natural Farming (KNF) handbook, where it is referred to as WCA (shorthand for Water-Soluble Calcium). Or, if you are not that into acronyms (and boy are there are lot of acronyms in the world of KNF and JADAM!), you can just call it eggshell extract. I love it because it is SO easy and it makes all my spent eggshells feel really useful (big egg-eating household over here!).

Calcium is critical to the formation of strong cell walls in plants as well as helping to facilitate the absorption of other minerals and nutrients to ensure disease resistance and healthy growth. If your flower crops do not have access to enough soluble calcium, the stems of your flowers will be weak. A prime example of this that many flower farmers will know is split stems on anemones, which is one of the reasons I started using the WCA eggshell extract in the first place!

Calcium also plays a critical role in soil structure, helping push soil particles apart for better aeration and drainage. You will want to make sure to soil test regularly (I soil test each August at my farm) so you can keep an eye on mineral levels. Make sure the soil lab/test you choose will do a full spectrum on minerals, not just the macro nutrients, NPK. For calcium, look for about 68% saturation in your soil. A little more or a little less is not cause for concern, but major deviations should be addressed. In certain parts of my farm, there is only 47% saturation of calcium and the soil there is “tight” with poor drainage. Adding WCA eggshell extract is slowly helping to loosen them up. I’ve also found drenching chickweed infested beds with eggshell extract WCA is one way to fight this weed that is there to mine calcium from the subsoil to add it to the top soil as nature tries to bring soil into balance through species successioning. By adding the eggshell extract, I seem to have been able to help nature skip ahead and the chickweed died out. But more on that later…

One thing I did not know when I first started using eggshell extract around the farm was that calcium is taken into plants almost exclusively via transpiration. It is not very mobile when applied to plant tissue itself. In other words, it is best to use WCA eggshell extract as a soil drenchat the roots of the plant rather than a foliar feed sprayed onto the leaves. That being said, I have used it regularly as part of my routine foliar feed for dahlias and it seems to still be effective. Several respected resources for KNF reference using it in foliar sprays as well. So just consider your objective when using it in order to choose the best delivery method; when in doubt, just use it as a drench.

One other note here: Tony of Bare Mountain Farm, who has continually and generously mentored me in KNF practices, recently mentioned that I might want to try another variation of this extract process that uses charred bones rather than eggshells so the resulting liquid would contain both calcium and phosphorous, which is even better for plants in the flowering stage of growth. I have not tried this preparation myself yet (somehow bones scare me <shrug>), but Tony has a great video on it here that you can check outif you’re curious.

EGGSHELL EXTRACT or WCA

Goal: To extract the calcium in eggshells and suspend it in a liquid soluble form that can then be applied to the soil as a drench. Helps strengthen weak stems and loosens compacted soils, among other things.

Ingredients
Eggshells (try starting with a dozen; scale up or down as desired after that)
Organic raw apple cider vinegar or organic brown rice vinegar (about quart if you’re using a dozen eggs)

Tools
Large glass jar, such as a quart or gallon canning jar
Paper towel or cheese cloth
Large rubber band

To Make:

Place the eggshells in a heavy skillet over medium heat to start. Use the back of a spatula to crush the shells up into smaller pieces. No need to go crazy with crushing at this stage. Just break them up so heat gets around all the pieces more evenly. After about four or five minutes on medium heat, lower the heat to low and put a lid on the skillet. Let the shells sit on low heat until they are toasted golden brown. This usually takes about 10-12 minutes, but sometimes I walk away and get busy and they’re on the stove for 30 minutes and it doesn’t seem to matter.

Turn off the heat and let cool completely. Once cool, crush the eggshells into even smaller pieces. You can do this with the back of the spatula again or you can put the shells into the glass jar, screw on the lid tightly, and give them a real good shake. Just don’t add the vinegar yet!!

After the eggshells are toasted and placed in the bottom of the jar, it’s time to add the vinegar. You are looking for a ratio of 1 part eggshells to 10 parts vinegar. To give you some idea, a dozen medium-sized eggshells usually is a good amount for a quart-sized jar to achieve that 1:10 ratio. Slowly pour the vinegar over the eggshells, stopping about halfway in case there’s a quick chemical reaction that creates super fizz. Once you’re sure nothing crazy is going to happen, fill the jar up the rest of the way, leaving about one inch of space at the top so bubbling won’t cause it to overflow.

You’ll notice rapid bubbling almost immediately. This is the vinegar extracting the calcium. Place a paper towel or cheese cloth over the mouth of the jar and secure with the rubber band. Never put the lid on the jar when in the process of making WCA eggshell extract as it creates a lot of gas that needs to escape.

Let the jar sit for 7-10 days. If you are in a hurry, you can decant the extract after just 5 days but it may not be as strong. If you totally forget about the jar for a month, not to worry. It’ll still be good to use. When you’re ready to call the extract “done”, strain the liquid through cheese cloth or a fine mesh strainer to catch any remaining pieces of eggshell. Place liquid in a sealable container with a tight-fitting lid. I usually just pour mine back into the same jar in which it was brewed. Label the jar so you remember what it is and when it was made. You’ll notice that while there will still be a hint of vinegar smell to the extract, most of the typical “zip” of vinegar is gone. Thus you won’t burn your plants when applying it.

What’s nice about this particular extract is that it is totally self-stable and does not “expire”. So you can make a big batch over the winter here and keep using it all throughout this coming season! I keep my jar in my flower cooler so it’s always handy at the farm for use. It doesn’t technically need to be refrigerated, but you do need to keep it away from sunlight.

To Use:Dilute at a ratio of 1:500 to 1:1000. Here at my farm, I typically use 1 teaspoon of the eggshell extract for each gallon of water which is a ratio of about 1:757.It can be applied to the soil with a watering can or used as a foliar feed in a sprayer. You can mix it with leaf mold tea to apply both at once.

Never use pure concentrated eggshell extract on your planting beds as that will really throw your soil and crops off balance!

If you’re more of a visual learner, here’s the video by Chris Trump that I used originally to learn how to make eggshell extract or WCA.

Come back to the blog soon to learn about a third easy (and powerful!) homemade regenerative input for your farm: nettle tea. Woot! In the meantime, get your regenerative flower farming fix by reading past posts here on this blog.