Unlocking the Composting Potential of Eggshells

  • By: Sam Richards
  • Date: June 28, 2023
  • Time to read: 6 min.

The natural process of composting holds a vital role in waste management and environmental stewardship, proving itself indispensable to both home gardeners and large-scale farmers alike. Composting transforms everyday organic waste into a nutrient-rich soil conditioner, a black gold teeming with beneficial microorganisms, ready to enhance our gardens’ fertility and productivity.

With such an effective system in place, it becomes crucial to maximize the use of kitchen waste, ensuring we not only reduce landfill contributions but also provide our gardens with diverse, balanced nutrients. From the usual suspects like fruit and vegetable peels, leaves, or coffee grounds, to other less commonly used materials, we can enrich our compost piles and, consequently, our soil.

One such material, often relegated to the trash bin, is the humble eggshell. Despite their seeming fragility, eggshells can offer a nutrient boost to our compost and gardens. This article seeks to shed light on the many aspects of composting eggshells, from their composition and benefits to the process and potential risks involved, answering the fundamental question, “Can I compost eggshells?”

Detailed Examination of Eggshells

Eggshells, while delicate to the touch, are incredibly robust when it comes to their nutritional composition. Their primary constituent is calcium carbonate, a compound that makes up about 95% of the shell. This mineral substance can act as a significant boon for the soil and plants when incorporated through composting. Eggshells also contain trace amounts of other essential nutrients, such as phosphorus, magnesium, and potassium.

Let’s take a more in-depth look into the benefits that eggshells can provide when integrated into your garden:

  1. Rich Source of Calcium: Calcium is an essential nutrient for plant growth, aiding in the formation of cell walls and promoting overall plant strength and health.
  2. Balancing Soil pH: Crushed eggshells can help maintain or increase the pH level of your garden soil, making it less acidic. This balance can be particularly beneficial for plants that thrive in neutral to alkaline soils.
  3. Deterrence of Pests: When used in compost or directly in the garden, the sharp edges of crushed eggshells can deter soft-bodied pests like slugs and snails.
  4. Improved Plant Growth: With a calcium boost from eggshells, plants can see improved growth and productivity. Calcium can help prevent blossom end rot in tomatoes and other fruiting plants.
  5. Waste Reduction: By composting eggshells, you contribute to reducing kitchen waste that would otherwise end up in the landfill.

Eggshells, with their unique structure, take longer to break down compared to other compostable materials, which can lead to some considerations when including them in your composting practices. However, their wide-ranging benefits can outweigh these concerns, making them a worthy addition to your compost pile.

The Process of Composting Eggshells: A Step-by-Step Guide

Composting eggshells is a relatively simple process, but due to their hard, brittle nature, they require some preparatory steps to ensure they decompose effectively. Below is a more detailed walkthrough of the eggshell composting process:

1. Rinse the Eggshells: After cracking open an egg, rinse out the shell to remove any remaining egg residue. This step is crucial as leftover egg material could potentially attract pests or create unpleasant odors in your compost bin or pile.

2. Dry the Eggshells: Let the rinsed eggshells dry completely. You can leave them on a paper towel, plate, or tray in a sunny or well-ventilated area. This drying step can help to prevent mold growth and makes the eggshells easier to crush.

3. Crush the Eggshells: Once the eggshells are dry, crush them into smaller pieces. This step expedites their decomposition process as the increased surface area allows the composting microbes to access and break down the eggshell material more readily. You can use a pestle and mortar, a rolling pin, or even a blender for large quantities.

4. Add to Your Compost Pile or Bin: You can now add the crushed eggshells directly to your compost pile or bin. They are considered “green” compost material, meaning they contribute essential minerals, and they can be mixed in with both green (e.g., vegetable scraps, coffee grounds) and brown materials (e.g., dry leaves, cardboard).

5. Turning Your Compost: Regularly turning or mixing your compost ensures that the eggshells are well integrated and exposed to the heat and microbial action needed for decomposition. It also promotes aeration, a vital factor for effective composting.

6. Wait for the Magic to Happen: Over time, the eggshells will break down and enrich your compost with calcium and other nutrients. While the decomposition process for eggshells is slower than other compost materials, patience will reward you with nutrient-rich compost that your plants will love.

Remember, composting is more of an art than a science, and every compost pile or bin will have its unique characteristics. Don’t worry if things aren’t perfect – with a bit of time and attention, you’ll find a system that works best for you and your garden.

Why are eggshells good for compost?

Eggshells add a significant amount of calcium to your compost. This nutrient helps plants build cell walls, contributing to their overall strength and vitality. Moreover, adding eggshells to compost can help balance the pH of your compost pile, making it a more hospitable environment for the microorganisms that break down organic matter.

Risks and Limitations of Composting Eggshells

While eggshells are beneficial to compost, they do come with certain limitations. They decompose slowly compared to other compost materials. Additionally, unwashed eggshells may attract pests to your compost pile, and eggshells from a sick chicken could potentially spread disease


The practice of composting remains a powerful tool in the hands of gardeners and environmental enthusiasts, turning what was once considered waste into a treasure trove of nutrients for the earth. The humble eggshell, often overlooked and underutilized, can play a significant role in this transformative process, lending a rich supply of calcium and trace elements to the compost pile and, subsequently, our gardens.

Incorporating eggshells into composting practices requires a small investment of time and effort. This involves cleaning and crushing the shells before adding them to the compost pile, ensuring their decomposition process unfolds smoothly. It’s worth noting that despite their hardy nature, eggshells decompose at a slower rate than softer organic materials, inviting a level of patience from the composter.

However, the payoff from this patience and diligence can be substantial. From providing essential calcium to balancing soil pH and deterring certain pests, composted eggshells can offer a range of benefits to plants and the overall garden ecosystem. And let’s not forget their contribution to reducing kitchen waste that would otherwise find its way to landfills.

Although composting eggshells comes with its limitations and potential risks, such as the potential to attract pests or spread disease if not properly prepared, the benefits generally outweigh the drawbacks. A key takeaway here is the importance of cleaning and crushing eggshells properly before composting them.

In conclusion, next time you crack open an egg, consider the potential held within its shell. Rather than relegating it to the trash, give it a second life in your compost pile. The soil in your garden, teeming with life and hungry for nutrients, will thank you. Your flourishing plants, nourished and vital, will stand as a testament to the remarkable transformation of eggshells from waste to black gold.

FAQ about Composting Eggshells

Do eggshells in compost attract rats?

Not typically, as long as they are clean and crushed. Egg residue, however, can attract rats and other pests.

Do eggshells keep bugs away?

Crushed eggshells can deter some bugs like slugs and beetles when sprinkled around plants.

How do eggshells prevent slugs and bugs?

The sharp edges of crushed eggshells can be uncomfortable for slugs and bugs to crawl over, thus serving as a natural deterrent.

Are eggshells good for plants?

Absolutely! Eggshells provide calcium, which is an essential nutrient for plant growth and strength.

Can You Compost Boiled or Cooked Eggshells?

Yes, you can compost boiled or cooked eggshells. Just make sure to rinse them thoroughly to remove any food residue or seasoning.

Should You Wash Eggshells Before Composting Them?

Yes, washing eggshells before composting helps to remove any egg residue and prevent the attraction of pests.

How long does it take for eggshells to compost?

The decomposition time for eggshells in compost can vary depending on factors like temperature and moisture, but it typically takes about 3-6 months.

Can you put too many eggshells in your compost?

While eggshells are beneficial, too many can alter the pH balance of your compost. It’s best to use them as part of a varied compost mix.

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