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Eggshells in Compost: Yay or Nay?

Eggshells in Compost Yay or Nay

Do you ever think about using empty eggshells instead of throwing them in the trash can? If you’re a gardener, you’ve probably thought about this at one time or another, especially if you have a compost bin or pile.

So the big question is: can we compost eggshells? We’re sure you have other questions related to this, so let’s get right into it!

Can you compost eggshells?

Can you compost eggshells
Image by Gardener’s Path

You can absolutely compost eggshells. But, a word of caution – avoid composting whole eggs, especially if they’ve gone bad as their odor can attract unwanted scavengers like rats, raccoons, or skunks. 

When incorporated, they enrich the soil with calcium in the form of calcium carbonate, as well as some magnesium and potassium. And if you want them to break down faster, grind the shells into a fine powder before popping them in with your compost. 

If you’re concerned about salmonella from eggs contaminating your compost, we have the solution. Just use hot composting to ensure high temperatures eliminate any pathogens.

One last thing to note: eggshell calcium acts similarly to garden lime, gradually reducing soil acidity towards a neutral pH of 7.0 though it may require a significant quantity of eggshells to achieve this effect.

How to Use Eggshells in the Compost and Garden

How to Use Eggshells in the Compost and Garden
Image by Gardener’s Path

Now that we know eggshells are pretty great additions to our compost, let’s discover how to use them effectively.

Clean and dry the eggshells

Rinse eggshells to remove any residual egg white and yolk. Let eggshells air dry thoroughly to reduce the risk of mold in your compost.

Crush and grind the cleaned and dried eggshells

Crush or grind eggshells into smaller pieces using a mortar and pestle, rolling pin, or food processor. We recommend going this route as smaller pieces blend better with other organic materials in your compost.

Mix the ground powdered eggshells in the compost

Distribute uniformly to benefit all areas of your garden soil when using the compost. You can alternate layers of kitchen scraps, yard waste, and eggshells.

Doing so encourages a balanced composition of greens (nitrogen-rich) and browns (carbon-rich) for successful composting.

Maintain proper moisture levels in your compost

Eggshells can help absorb excess moisture if it’s too wet or retain moisture if it’s too dry. Keep an eye on moisture levels for a healthy composting process.

Composting is gradual as eggshells take time to decompose. Regularly turn and aerate your compost pile for efficient decomposition.

Prevent potential odors and accelerate decomposition. Once ready, use the compost to enrich your garden soil to feed plants like tomatoes and peppers with calcium.

Planter’s Tips

  • Crushed eggshells serve as a natural pest deterrent when mixed into the soil, especially against snails and slugs, thanks to their abrasive texture. 
  • Adding crushed eggshells to the soil regularly not only helps keep pests at bay but also contributes to enhancing soil structure and fertility gradually.

How long do eggshells take to break down?

How long do eggshells take to break down
Image by Bustling Nest
FactorsSmall FragmentsFinely Ground Powder
Decomposition TimeApproximately a year or more, depending on compost conditionsFew months or less than a year, depending on compost conditions
Availability to PlantsTakes longer to become availableBecomes available shortly after application

When finely ground into a powder, eggshells break down faster and become available to plants shortly after application. Usually, it takes a few months and less than a year.

To create eggshell powder, grind them in a coffee grinder, mix it with water, and apply it to your soil. Another option is to place the powder in the hole when you’re transplanting indoor seedlings to the garden.

Are eggshells sustainable for garden or compost use?

Eggshells are sustainable for garden or compost use. The gradual breakdown releases calcium, enhancing soil structure. 

The crushed eggshells also deter pests like slugs and snails due to their sharp edges. This eco-friendly practice recycles eggshells, reducing waste while providing plants with a natural nutrient source.

Myths Surrounding Eggshells in Compost

Myths Surrounding Eggshells in Compost
Image by Gardener’s Path

While eggshells can be a valuable addition to your compost, there are some common myths and misconceptions that have circulated. Let’s debunk 5 of the most common myths and clarify the facts!

Myth 1: Eggshells attract pests.

Fact: Crushed eggshells deter pests rather than attract them. 

The sharp edges of crushed eggshells can be uncomfortable for pests like slugs and snails. When properly incorporated into your compost, eggshells can help protect your garden from these nuisances.

Myth 2: Eggshells acidify the soil.

Fact: Eggshells are alkaline in nature and can help balance the pH in your compost, preventing it from becoming too acidic. 

However, this doesn’t mean they make your soil excessively alkaline. In the composting process, the shells break down gradually, releasing calcium and neutralizing acidity.

Myth 3: Eggshells harbor harmful bacteria.

Fact: The high-heat composting process, which is essential for breaking down organic matter, effectively kills off most harmful bacteria and pathogens.

Properly managed compost piles maintain the necessary temperature to render any potential risks from eggshells negligible.

Myth 4: Eggshells are not worth the effort.

Fact: Eggshells are valuable and low-effort additions to your compost. 

Considering the benefits they offer, such as calcium enrichment, pH balance, and pest deterrence, the minimal effort required to prepare and incorporate them is well worth it.

Myth 5: Eggshells don’t contribute much to compost

Fact: Eggshells alone won’t revolutionize your compost but they play a crucial role in enhancing its overall quality. 

The calcium, pH-balancing properties, and pest control benefits make them a valuable component in the mix.

Eggshell Substitutes to Use for Composting or Gardening

Eggshell Substitutes to Use for Composting or Gardening
Image by Jobe’s Company

If you’re not sure about using eggshells, several compostable materials can be used as substitutes or additions to your compost. Here’s a quick look at them.

Compost MaterialBenefits
Coffee Grounds• Adds nitrogen
• Improves soil structure
• Enhances drainage.
Fruit and Vegetable Peels• Rich in organic matter
• Adds nutrients to the compost.
Grass Clippings• Provides nitrogen
• Promotes microbial activity.
Shredded Leaves• Adds carbon
• Helps balance the carbon-to-nitrogen ratio.
Tea Bags• Decomposes quickly
• Adds organic matter to the compost.
Cardboard• Adds carbon
• Helps prevent compaction in the compost pile.

Note that these are also vegan-friendly options, so these might work if you’re looking to add materials similar to eggshells.

Why Eggshells Are Good for Compost

Why Eggshells Are Good for Compost
Image by Food Hacks – WonderHowTo

So eggshells add more goodness to your compost, but what exactly do they contribute? Let’s check the benefits below.

Calcium Enrichment

Eggshells are mainly made of calcium carbonate. When you add crushed or powdered eggshells to your compost, you’re supplying a slow-release calcium source that supports robust cell walls and root development in plants.

pH Balancing

Composting can sometimes lower pH levels, making the soil more acidic. Eggshells, being alkaline, help balance the pH in your compost. 

This is especially helpful when composting acidic items like citrus peels. Including eggshells prevents excessive acidity from other composting materials that can harm your plants.

Pest Deterrence

Concerns about eggshells attracting pests are unfounded. Properly crushed and mixed into the compost, eggshells actually repel pests. 

The sharp edges of crushed eggshells deter common garden pests such as slugs and snails, providing natural pest control for your plants.

Pathogen Reduction

Eggshells also aid in reducing harmful pathogens in your compost. High-heat composting effectively eliminates most harmful microorganisms during the decomposition of kitchen waste. 

So you needn’t worry about any pathogen risks. Adding eggshells doesn’t introduce additional risks if you manage your compost correctly.

Tips for Successful Composting with Eggshells

Tips for Successful Composting with Eggshells
Image by Asia Farming

Aside from crushing and grinding your eggshells into fine powder, we’ve got more tips and tricks up our sleeves! 

  • When adding eggshells to your compost, ensure they are thoroughly mixed with other compostable materials to help in the efficient breakdown of all organic matter.
  • Composting is most effective when you layer and alternate “greens” (nitrogen-rich materials like kitchen scraps) and “browns” (carbon-rich materials like dried leaves). 
  • Compost piles should be kept consistently moist but not soggy. 
  • Turn and aerate your compost pile regularly to help mix the eggshells with other compostables and provide oxygen to beneficial microorganisms.
  • Investing in a good-quality compost bin or creating a well-structured compost pile can help regulate temperature, moisture, and aeration, ensuring optimal conditions for decomposition, including eggshells.
  • Composting generates heat as microorganisms break down organic matter, so keep an eye on the temperature, making sure it ranges between 130 to 160 F for proper decomposition.
  • If you’re unable to process your eggshells immediately, store them in a separate container in your kitchen to keep them clean and dry until you’re ready to add them to your compost.

What Not to Use with Eggshells in Compost

What Not to Use with Eggshells in Compost
Image by Dreamstime

While eggshells can be a valuable addition to your compost, there are certain materials that should be avoided when mixing them into your compost pile. We’ve got the info so you can easily avoid these common mistakes!

Meat and Dairy Products

Meat, bones, and dairy products can introduce pathogens and undesirable odors to your compost. These materials may also attract pests so keep them separate from your eggshells.

Fats and Oils

Cooking oils, grease, and fatty food scraps should be avoided. They can slow down the composting process and create a slimy, unpleasant environment.

Pet Waste

Pet waste, including cat litter and dog feces, should not be composted with eggshells. It can contain harmful pathogens that are best avoided in garden compost.

Diseased or Pest-Infested Plants

While it can be tempting to add plants or plant parts to your compost, avoid adding those that have been affected by diseases or pests. Even if you have a hot compost, the process doesn’t always destroy these issues. 

Plus, you risk reintroducing them in your garden when using the compost.

Invasive Weeds

Weeds that can easily spread in your garden, especially those with seeds, are not the best materials for composting. The high temperatures in a properly managed compost pile may not kill weed seeds.

The result? You could end up spreading them throughout your garden.

Coal or Charcoal Ash

Coal or charcoal ash contains materials that can be harmful to plants and should not be included in your compost.

Non-Biodegradable Materials

Plastics, metals, glass, and other non-biodegradable materials should never be added to your compost pile. These materials easily contaminate the compost and disrupt the decomposition process.

Chemically-Treated Materials

Avoid composting materials that have been treated with chemicals, such as wood treated with preservatives. Even though the treatments might have been some time ago, chemicals may seep through the compost and harm your plants.

Inorganic Materials

Items like rubber, synthetic fabrics, or any other materials that do not naturally decompose should not be included in your compost. They’ll just end up polluting your garden soil.

Large Branches or Woody Stems

While small twigs and branches can be composted, large or woody materials take a very long time to break down and may disrupt the composting process. If you still want to make use of them, chop or break them down into smaller bits.


Do you have to wash eggshells before composting?

You need to wash eggshells before composting to remove any residual egg whites or yolks. This helps prevent the compost from attracting pests or developing unpleasant odors.

What plants don’t like eggshells?

Plants that don’t like eggshells include potatoes, tomatoes, and peppers. These vegetables thrive in slightly acidic soil, while eggshells, being alkaline, disrupt the pH balance.

Can I compost eggshells with colored dyes?

You can’t compost eggshells with colored dyes. The dyes may contain chemicals that can be harmful to your compost and garden and you might end up contaminating your soil with unwanted chemicals.

Are there any precautions for using eggshells in compost in very cold or hot climates?

There are precautions for using eggshells in compost in very cold or hot climates. In extremely cold climates, crush the eggshells even more finely to speed up decomposition. 

In very hot climates, monitor the moisture levels to prevent the compost from drying out too quickly.

Can I use eggshells in vermicomposting or composting with worms?

Eggshells can be used in vermicomposting or composting with worms. Crushed eggshells can help maintain a neutral pH and provide additional calcium, which can be beneficial for the worms.

Can I compost eggshells with other types of shells, like seafood shells?

You can compost eggshells with other types of shells, like seafood shells. Seafood shells, such as crab or shrimp shells, can be composted alongside eggshells. 

However, keep in mind that these shells may take longer to decompose than softer materials.

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