Hidden Springs Homestead may earn a commission for purchases made after clicking links on this page. Learn More.
Eggshells, often discarded as waste, hold a remarkable potential to enrich your garden soil and promote the growth of healthy, vibrant plants in your vegetable garden.
This article will explore what calcium is and how it helps plants, how to use eggshells as a fertilizer to add calcium to garden soil, understand the importance of calcium for soil health, its many benefits for plants, and how to make your own DIY calcium powder using eggshells.
Let’s dive into using eggshells as a fertilizer and learn how this simple yet effective organic method can transform your garden yields. Calcium powder is available at garden stores, but why pay for it when it’s so simple to make?
If you have chickens and eat eggs, you can produce your own calcium powder as a natural fertilizer.
Updated February 2024.
What is Calcium?
Calcium is an essential element found in the soil alongside magnesium (Mg) and sulfur (S). It is considered a secondary macronutrient behind the primary macronutrients of Nitrogen (N), Phosphorus (P), and Potassium (K) because less of it is required for plant nutrition.
It’s an essential mineral in soil that plants use to grow strong and healthy. If calcium is too low or too high, plants suffer accordingly. It helps plants absorb potassium and phosphorus, stimulating photosynthesis and increasing plant growth.
Why Garden Plants Need Calcium
Calcium is crucial for plant growth. Just like us, plants need a balanced diet to thrive, and calcium is one of the essential nutrients. Calcium plays a vital role in several critical functions within the plant:
- Strengthens Cell Wall Structure: Calcium helps to form strong cell walls in plant tissues to protect plants from toxic compounds and provide structural support or strength against wind, rain and disease pressure.
- Regulates Nutrient Uptake: It aids in the uptake and transportation of potassium and phosphorus, stimulating photosynthesis and increasing plant growth and development for healthy plants.
- Enzyme Activator: Calcium is a co-factor for various enzymes involved in metabolic processes, including photosynthesis and hormone regulation.
How to Spot a Calcium Deficiency
Without an adequate supply of calcium, plants can suffer from a host of issues. Such as
- Stunted growth – the plants root balls can be smaller which results in unhealthy plants
- Blossom End Rot in vegetables like tomatoes and peppers – the bottom of tomatoes will have a rotten looking spot while peppers will can have rotten spots on its sides.
- Overall weakened health – parts of the plant leaves will begin to curl or new leaves will look stuck together
How Much Calcium Do Plants Need?
Calcium amounts needed in plants vary based on the species and family. Grasses like corn or alliums need only small amounts of calcium. While vegetable crops in the brassica family, such as cabbage, broccoli, kale, etc, will require more.
How to Make Eggshell Fertilizer
Step One: Storing Eggshells for Making Calcium Fertilizer
After enjoying fresh eggs for your meal, you’ve got a choice. You can either
- toss the shells into a bowl to dry as is for a day or two or
- rinse them with water by running your finger around in the shell to remove residue. Try not to remove the membrane, then lay them aside to dry for a day.
NOTE: I have had eggs mold when I didn’t rinse them well. But not often. It’s when I go for several days or weeks, saving them before I get around to grinding them. This tends to be in the summer months when I’m doing a lot of canning and have a hard time keeping up.
They tend to be more sticky when crushing or grinding the “unwashed” eggs. I think it is due to some remnants of the Albuman, clear white liquid. Therefore, I prefer to rinse them if at all possible.
I keep mine in a plastic ice cream container sitting inside a bottom cabinet. It’s not pretty, but it works well with the plastic lid.
Our chickens lay a rainbow of eggs, so it’s often colorful but not something I want to leave sitting on the counter.
Step Two: Crushing Eggshells As Garden Calcium
In a blender, mortar and pestle, or even a coffee grinder, crush eggshells into a fine powder. I use a blender, pour in dry shells, place on the lid, and blend for 1-2 minutes or until eggshells are fine powder.
To make crushing shells a bit easier, you can bake them in the oven at 350°F for about 15 min or cook them in a microwave for about 1 minute. Doing this makes the shells more brittle for grinding.
TIP: If you use a blender, I recommend setting it aside strictly for making calcium powder and things you will not eat.
The blender bowl will get lots of scratches and turn a white color. You can see the image below with the distinct line around the top. These are scratches and don’t wash off.
After blending, remove the lid just slightly! Give the white powdery puff inside to settle before taking it off. The powdery smoke is safe, just a bit messy.
Step Three: Storing Eggshell Calcium Fertilizer
Once the shells are well blended, using a wide-mouth funnel, pour calcium powder into a container with a tight-fitting lid. I use a second plastic ice cream container.
This works well for carrying out to the garden with its handle, and then it’s wide enough to easily get my hand into for spreading it over the soil or around plants.
Any container with a tight-fitting lid will work.
This whole process takes about 3 minutes!
How to Use Eggshells in the Garden for Added Calcium
Eggshells as calcium in the garden can be used in several different ways
- As calcium: When amending soil for spring planting, sprinkle a few handfuls around on the soil and blend in. It will add macronutrients to your soil.
- Add powder to your compost pile. I add the powder by the cups to my compost. There is no specific amount, and it only improves the compost
- Add two to three teaspoons to the soil when planting herbs in containers. The roots will absorb the calcium as it breaks down.
- Add powdered eggshell calcium powder to holes when transplanting tomatoes and peppers. The added calcium will help to prevent blossom end rot. Putting it directly in the whole will ensure the roots take up the calcium as the powder decomposes.
- Sprinkle around plants to use as an organic pest control to deter snails, slugs and more from their favorite plants like green beans, peas, and potatoes.
RELATED: Even if you’ve never gardened before, this ultimate guide for beginners is for you! Learn everything you need to know from over 60 resources, all in one place, to be a successful gardener, including improving soil, cover crops, warm and cool season crops, organic amendments, fertilizing, watering, and so much more.
It’s that easy! Crushed eggshells can boost your garden soil calcium and are a no-cost organic slow-release fertilizer that improves plant growth as well control garden pests.
So tell me, will you stop tossing your eggshells in the trash and start making your own DIY eggshell fertilizer?
More Gardening Articles
- How to Improve Soil Quality Naturally
- Garden Mapping: How to Plan and Organize Your Vegetable Garden
- 14 Must Have Garden Tools for Home Gardeners
- Best Tips for Starting a Garden From Scratch
- 7 Tips to Prepare Before Spring Gardening
Connect with Hidden Springs Homestead!
Be sure to follow me on social media so you never miss a post!
Dianne Hadorn is the owner of Hidden Springs Homestead nestled in the hills of East Tennessee. She is a Master Gardener and enjoys helping others learn how to grow and preserve their own food and sharing tips for living a more sustainable life.
Although I sometimes keep them separate & apply separately, most of the time I simply add them to our compost collection.
Good information I use a mortal pestle a pumice black lava rock mortal and pestle I ground to a fine powder my soul looks and smells so earthy
We have been using eggshells for quite awhile.Instead of using a blender, we use a coffee grinder instead.It’s more compact,and we use it only for the eggshells.Has worked for us for years.(easy clean also)
This is great! We do this as well, only we dry ours out in a metal bucket on top of our woodstove. Then we pulverize them in our blender and add to the garden. We also sometimes feed them back to our ducks and chickens so they can have some more calcium as well. MUCH cheaper than the oyster shells for sale for the same purpose!
I use egg shells even on my house plants and in the summer I save all my egg shells to go into my garden in the summer -put them around my roses too.
I dig a hole in the soil, drop the days’ shells in, and refill the hole. They break down slowly for a continuous calcium and organic matter boost. In winter I toss the shells as well as meat bones into the wood stove. Well fed soil makes for well fed people!
Robin, I love the idea of tossing them into the wood stove. Great idea!
i do feed back my shells in hard winter to the hens, but as soon as they are “foraging” I switch over and use the shells in the garden from spring to fall.. I have been doing so for many years now 🙂
I think its very worth it.
its a great way to recycle and reuse them. They have way too much value to toss out. I’m glad you use yours too.
I have been doing this since I was a kid. Never had a problem with chickens eating eggs.
Great idea, Dianne! I’ve been feeding my egg shells back to my hens, but I’ve noticed lately they aren’t as interested in them. Hmmm….they may be sharing with the garden this year!