These 6 Benefits of Eggshells in the Garden Will Surprise You! - No Plant No Life

Saturday, August 5, 2023

These 6 Benefits of Eggshells in the Garden Will Surprise You!

Eggs, those delightful additions that every home cook treasures, sometimes become a bit of a challenge for home composters, especially their shells. 

I can still vividly remember the time I eagerly delved into my first batch of finished compost, only to realize that while all the food scraps and garden cuttings had transformed into this beautiful, rich, soil-like substance, the eggshells were still pretty much intact. 

It was like they were resisting breaking down, and it messed up what would have been perfect compost.

But you know what? I was determined to figure this out, and after making a few adjustments to my composting routine, I can happily say I don't come across those big eggshell pieces in my compost anymore. 

And here's the exciting part – not only did I crack the code to proper composting with eggshells, but I also discovered 6 benefits of using eggshells in the garden that completely shocked me. 

The good news is that you'll soon learn everything there is to know about them!

In this article, we'll discuss the most effective ways to incorporate eggshells into your compost as well as the incredible advantages they have for your garden. 

And here's something interesting we're going to dive into: can eggshells actually keep pests away? 

It's a clever gardening tip that could truly aid in safeguarding your priceless plants from those bothersome creatures.

You're in for a treat if you've been wondering why eggshells persist in your compost or if you're just interested in how valuable these unassuming shells can be in gardening. 

Let's investigate the secrets of using eggshells in gardening, discover 6 fantastic benefits they provide, and figure out how to maximize these amazing advantages.

1. Eggshells as Food Waste

Eggshells, in their whole form, can occupy a significant amount of space, whether they find their way into your compost pile or your household trash can. 

Those aesthetically pleasing ovals, designed perfectly to encase their contents, don't conform easily when tossed into the trash – unless you're willing to put in the effort to crush them.


The casual disposal of eggshells into the garbage is a common practice for many, often done without a second thought. 

Surprisingly, this seemingly harmless action accumulates into a substantial environmental concern. 

In the words of Paula Felps at Earth911, a staggering 150,000 tons of eggshells find their way to landfills annually in the United States alone.

Now, let's do the math together. That equates to nearly a million pounds of these seemingly innocuous oval wonders monopolizing landfill space, not over the course of a year, but each and every day. A realization that certainly makes you pause and reflect.

Given these numbers, it's only logical to seek alternative purposes for these discarded remnants of eggy delights. 

And this is precisely where the participation of home gardeners becomes crucial. 

As we delve into the creative uses of eggshells, we begin to tap into a realm of sustainability, resourcefulness, and an opportunity to contribute positively to the environment. 

So, if you're ready to uncover the potential of these overlooked treasures and embark on a journey of garden-friendly practices, you're in for an eye-opening adventure. Let's dive in!

2. Eggshells as a Source of Nutrient

Let's kick things off by delving into the fascinating world of repurposing food waste in your garden. 

But before we jump into the nitty-gritty details, let's take a moment to realize the enormity of what's being discarded – nearly a million pounds a day!

Imagine this: a close-up of those bright white eggshells, some still holding a bit of the egg white, placed on a rustic wooden surface. Now, let's break down what makes up the average eggshell:

  • 95% calcium carbonate
  • 0.3% phosphorus
  • 0.3% magnesium
  • A touch of sodium, potassium, zinc, manganese, iron, and copper

It's quite a waste to toss away all these valuable nutrients, isn't it? Here's another snapshot for you: a wooden spoon filled with dried and crushed eggshells, forming a fine powder, resting on a clean white surface. 

And you know what's even more remarkable? These eggshells might just replace a store-bought garden product, like agricultural lime.

In fact, back in 2006, there was a study presented at the Iowa State University Integrated Crop Management Conference by experts John Holmes and Paul Kassel. 

They found that eggshells can effectively combat soil acidity, performing at the same level as agricultural lime – the kind mined from limestone.

Now, picture this: a bunch of discarded eggshells scattered on the ground, mingling with straw and fallen leaves in the backdrop. 

And here's a fun fact – repurposing food waste like this isn't just a DIY trick for home gardeners.

Did you know that ground eggshell meal is actually listed as an organic fertilizer? Yep, it's considered "generally acceptable under the rules of the USDA National Organic Program (NOP)" for commercial organic farmers. 

This info comes straight from the North Carolina Extension Gardener Handbook published by North Carolina State University. The average analysis of eggshell meal gives us 1.2-0.4-0.1 (NPK), in case you were curious.

Sure, the levels of nitrogen, phosphorus, and potassium offered by eggshells might not be super high, but here's the gem: what we commonly toss as trash can be an incredible calcium source. 

It works wonders as an amendment that nourishes plants and balances out acidic soil. Quite the gardening goldmine hidden in those eggshells, right?

3. Use as a Soil Amendment

How can you figure out if your garden could benefit from a boost of calcium?

First things first, you need to know your soil type, you might even consider conducting a soil test to get a handle on the calcium levels in your soil.

Now, if your soil happens to be on the acidic side, adding some calcium might be a game-changer, depending on what you're aiming to grow.

Picture a berry tree thriving in your garden, loaded with those delicious ripe purple fruits and surrounded by vibrant green leaves.

But here's the twist – there are cases when acidic soil is exactly what you want, like when you're nurturing blueberries or other ericaceous plants. 

In those situations, introducing an alkaline amendment like calcium might not be the best move.

The results from your soil test will play captain and guide you in deciding if calcium is the right addition for your soil.

Ever seen a pile of crushed eggshells sitting on soil? Now, if you're growing tomatoes or other crops prone to blossom-end rot, these eggshells packed with calcium can be a real lifesaver during planting.

In a study published in the March 2016 issue of the International Journal of Innovative Research in Science, Engineering, and Technology, Madhavi Gaonkar and A. P. Chakraborty from Dr. Babasaheb Amebedkar University in Maharashtra, India, explored how eggshells could work as a calcium supplement and fertilizer.

These researchers concluded that powdered eggshells are possibly the finest natural calcium source around. 

They even found that using this amendment could balance soil calcium levels, helping fend off blossom-end rot.

Let's talk about tomatoes for a moment – those annoying blackened, decaying ends known as blossom-end rot. 

Charles C. Mitchell, an extension agronomist at the Alabama Cooperative Extension, took a close look at using eggshells in farm soil to counter acidity.

Guess what? He discovered that simply tossing crushed eggshells into the soil didn't cut it – they needed to be ground to a fine powder, finer than sand. 

When he did that, the powdered shells outperformed agricultural lime, providing a readily available calcium source for plants.

To sum up, those large shell pieces take their time breaking down, not making the best amendment or soil sweetener. 

But when ground into a fine powder, they integrate with the soil, becoming easily accessible to plants and tweaking the soil pH.

Apart from nipping blossom-end rot in the bud for tomatoes, ground-up shells with their calcium goodness can also come to the rescue against apple cork spots or serve as a lime substitute for your lawn.

Now, before you start showering calcium all over your garden, take a pause. 

It might be a good idea to dive deeper into how plants make use of nutrients and minerals. 

After all, you want to make informed decisions about this soil amendment.

4. For Composting

If the idea of holding onto your used eggshells for enhancing your soil doesn't quite fit your plans, there are a couple of solid reasons why you might consider composting them rather than tossing them into the garbage. 

The first reason, as we've touched on before, is to make sure they don't just end up as landfill waste.

Here's the thing: in landfills, food waste takes ages to break down compared to the speedy process in compost heaps. 

Landfills create a sealed-off, oxygen-starved environment, leading to a smelly and inefficient type of decomposition known as anaerobic.

On the other hand, a well-maintained compost pile fosters aerobic decomposition – that's the good kind. 

It's all about oxygen-loving microbes that transform food scraps into valuable nutrients like nitrogen, phosphorus, and magnesium. Perfect fuel for growing more delicious food!

Now, if you're using an anaerobic method like bokashi composting at home, where you introduce Lactobacilli bacteria to kickstart fermentation, your eggshells will break down just fine.

Here's another thought behind composting those eggshells: it's like offering a better lifestyle to earthworms, whether in your compost heap or vermiculture bin.

You see, earthworms need a little grit to help with digestion. And guess what makes for fantastic grit? Finely ground eggshells, of course.

Even if you're not planning on having a worm bin, trust me, earthworms will eventually set up camp in your outdoor compost heap and in your garden soil. 

So, tossing in some crushed shell fragments is like offering them a VIP pass to thrive town.

Oh, and before you chuck those eggshells into your compost or worm bin, make sure to grind them into a powder. 

This step ensures that your final compost will have a smooth, soil-like texture, free from any large shell chunks. 

Just a quick note: while composting whole eggs isn't usually recommended, as their smell might attract rodents, breaking them down into shells is the way to go.

And here's a neat tip: grinding the shells before adding them not only helps the earthworms but also makes it easier for them to utilize the material as grit.

Stay tuned – I'll be sharing my method for safely preparing ground eggshells with you in a bit.

In the meantime, if you're curious about maintaining the right balance in your compost pile, take a look at our article that covers the basics of composting. It's a handy read to keep things on track!

5. Use as Containers for Starting Seeds

Another cool gardening idea for eggshells is to turn them into seed containers for your plants.

But hold on, before you dive into this creative adventure of upcycling your kitchen scraps, there are some key points to consider and a few steps to follow before you begin.

Now, this method of starting seeds works wonders for small, compact plants. 

However, if you're thinking about growing taller plants like tomato seedlings, these cute little eggshell containers won't cut it for long. They'll outgrow them before you can say "tomato."

But hey, don't let that discourage you from trying tomato seedlings – just be prepared with larger nursery pots to transfer them to a few weeks down the line.

Quick side note: multiple repotting aren't the best idea for most transplants, as it can stress out the plants and harm their roots.

On the flip side, low-growing plants like thyme, cucamelons, and certain types of succulents are prime candidates for this eggshell-starting approach.

Now, before you dive in, it's crucial, to begin with clean, sterile shells if you're planning to use them as seed pots.

Remember, thicker shells are less likely to break during cleaning compared to thinner ones.

Usually, eggshells from younger hens have a bit more thickness, while those from older hens might be thinner. 

If you're getting eggs from a farm, consider asking if they have eggs from younger layers.

Give the eggshells a gentle wash with warm, soapy water or give them a good boil in hot water to sanitize them. 

Now, besides a clean environment, young seedlings need good drainage.

Assuming you've managed to clean your eggshells without any cracks, the next step is to make two or three small holes in the bottom of each shell. 

This ensures your seedlings won't end up with soggy feet but will enjoy well-drained soil. 

You can use the tip of a metal paper clip for this task – it works like a charm.

When the time comes to put your seedlings in the ground, remember this: eggshells don't break down quickly, definitely not fast enough for your young plant's roots to stretch out.

Here's the deal – you'll need to extract the seedling from its shell before planting. 

You can gently lift the seedling out with a widger or a small spoon, or if you're feeling a bit dramatic, crack the shell to free the plant.

6. For Pest Deterrent 

Here's another clever way to put your excess eggshells to work in your garden: create a barrier by scattering sharp, crushed shell fragments around the bases of your plants. 

This can serve as a deterrent against specific pests with soft bodies like caterpillars that have a penchant for decapitating your delicate seedlings.

Also, cutworms love to munch on young seedling stems, so one defense strategy is to block their path by encircling seedlings with protective collars.

According to T. J. Martin from the Cochise County Master Gardeners office, scattering crushed eggshells around the stems of sensitive young seedlings can also effectively deter cutworms.

However, when it comes to discouraging slugs, crushed eggshells might not be as effective as they're often claimed to be – pun intended.

Jeff Gillman, author of "The Truth About Garden Remedies: What Works, What Doesn’t, and Why," conducted his own experiment to test this DIY slug deterrent.

Speaking of the book, I actually had the pleasure of attending a class with Gillman through the University of North Carolina at Charlotte’s Native Plants Studies program. We, the students, joined him in conducting this experiment.

Our testing ground? A paper plate. We created a barrier of crushed eggshells along the inner edge of the plate and placed the slugs in the center. 

The idea was to see if the jagged shells would keep the slugs away from the plate's center, or if they'd venture across.

Just for fun, we did the same experiment with pennies, as copper is another supposed slug-repellent.

The result? Neither barrier could stop the slugs in their tracks. Gillman's book describes how he tried various iterations of the slug-on-paper-plate test.

His most successful attempt involved crushing the shells to the size of baby aspirin and creating a 1/4-inch deep barrier. 

This did slow the slugs down a bit, but it still wasn't powerful enough to make them retreat or prevent them from crossing.

Curious about Gillman's recommended slug control? It's time for a spoiler – he suggests using beer traps.

It's important to mention that various slug species exist, and to my knowledge, Gillman's experiment hasn't covered a wide array of them. 

This means the eggshell barrier might work better against some species than others.

So, the jury's still out on whether this DIY hack truly stands up against garden slugs.

In any case, placing pieces of crushed, heat-dried eggshell around your plants is unlikely to harm them. Remember, they won't even alter your soil's pH in the short term.

Final Thought 

Intrigued by the potential of eggshells in your garden? These unassuming shells hold surprising benefits that can elevate your gardening game. 

From repurposing food waste to enriching soil and acting as nutrient-packed containers for seedlings, eggshells bring a world of possibilities. 

They're not just for composting; they can also act as a barrier against pests, offering an eco-friendly solution. 

So, whether you're seeking a greener way to nurture your plants or discovering innovative methods for a thriving garden, eggshells have more to offer than you might have thought.


Can I use eggshells as food waste in my garden?

Absolutely! Eggshells can be repurposed as a valuable source of nutrients for your garden. They offer a range of minerals that enrich the soil and promote plant growth.

How do eggshells act as a nutrient source for plants?

Eggshells contain essential minerals like calcium, phosphorus, and magnesium. When they break down in the soil, these nutrients become available to plants, supporting their health and development.

Can I use eggshells as a soil amendment?

Definitely. Crushed eggshells can enhance soil structure and help balance its pH. This is especially beneficial for plants that thrive in slightly alkaline conditions.

Can I compost eggshells?

Yes, eggshells can be composted. However, it's recommended to crush them into smaller pieces before adding them to the compost pile for quicker decomposition.

Can eggshells be used as containers for starting seeds?

Certainly. Eggshells can be repurposed as mini seedling containers. They provide a protective environment for germinating seeds and can be transplanted directly into the soil.

Do eggshells work as a pest deterrent?

Yes, crushed eggshells can act as a barrier against certain pests, like cutworms. They create an abrasive surface that pests avoid, helping to protect your plants.

Are eggshells effective for repelling slugs?

While eggshells are often suggested as a slug deterrent, their effectiveness varies. Some studies show mixed results, so additional methods like beer traps might be more reliable for slug control.

How should I prepare eggshells for use in the garden?

Clean and sterilize eggshells before using them. Crush them into smaller pieces to facilitate decomposition and ensure they don't pose a physical barrier for root growth.

Can eggshells alter the pH of the soil?

In the short term, eggshells have a minimal effect on soil pH. Their gradual breakdown releases calcium carbonate, which can slightly raise the pH, making them suitable for plants that prefer alkaline conditions.

Are there any limitations to using eggshells in the garden?

Eggshells are most effective for smaller, low-growing plants. Taller plants may outgrow the eggshell containers quickly. Additionally, while they offer benefits, eggshells alone may not fully replace specialized fertilizers and pest control methods.

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