Can You Compost Eggshells? (If Yes, Then How & Why)

Eggs are popular in households, and this protein-rich food is widely consumed. But what about the leftover eggshells? Well, you can use them for decoration or for growing tiny plants. Furthermore, being rich in calcium and other nutrients, they are also a great addition to your soil. But can you compost eggshells? If yes, then how?

Yes, you can compost eggshells as they contain rich amounts of calcium which helps improve the soil structure and aids plants in building cell walls. To compost eggshells, it’s best to crush them into fine pieces before adding them to the compost pile. 

How to Compost Eggshells?

Composting eggshells is possible, but these mineral materials take years to degrade if not done the right way. So, follow the steps below to make a healthy compost from eggshells that provide nutrient-rich humus for your plant growth.

paper towels in a compost pile

Step 1. Wash the Eggshells

Collect eggshells and wash them thoroughly to remove the inner membrane. Washing the shells kills the salmonella bacteria present in the egg and keeps the animals at bay. After washing them, dry the shells under the sun or dry them in the oven.

Step 2. Crush the Eggshells

Now, crush the dried eggshells into small pieces. You can use a mortar and pestle to crush them into small pieces or use a coffee grinder to make eggshell powder. The smaller the pieces, the better.

Crushing the shells will aid in the decomposition process.

Step 3. Add a layer of Brown Materials

First, add a layer of brown materials like paper towels, cardboard, dried leaves, dried branches, twigs, and wood chunks by breaking them into small pieces. Brown materials are rich in carbon and serve as a food source for the microbes in your compost bin.

Step 4. Mix Crushed Eggshells with Other Green Materials

Mix the crushed shells with other green composting materials like food scraps, yard waste, grass clippings, and kitchen waste like coffee grounds, potato peels, banana peels, and citrus peels.

Make a firm layer of these green materials on the brown ones.

Green materials are the source of Nitrogen and help the microbes grow and reproduce, and break down the food materials.

Step 5. Fill the Compost Bin

Continue adding the composting ingredients alternating the layers of brown and green materials. Then seal the compost heap with a firm layer of soil.

Cover your compost with a lid. It helps to conserve heat and accelerate the composting process. (You can use metal sheets, wire-mesh or heavy boards for this)

Step 6. Maintain your Compost Pile

Keep your compost pile damp by watering it regularly. Check the water content and add water accordingly. If your pile has too much water, add more brown materials to maintain the moisture.

Turn the compost pile with a pitchfork every 3-4 days initially. This will aerate the pile and help accelerate the decomposition.

After 2-6 months of maintaining your compost pile, you can harvest the finished compost and use it to enrich your garden soil.

Benefits of Composting Eggshells

Eggshells are a great source of composting material and have numerous benefits for soil. Here are a few benefits of using compost made of eggshells.

Composting Eggshells
  • It adds calcium and other essential nutrients to the soil and helps in plant growth.
  • It prevents the blossom end rot disease in several plants.
  • The nutrients in eggshells help adjust acidic soil by increasing the soil pH.
  • It is a cheap source of organic fertilizer and is readily available.
  • It is eco-friendly and reduces waste in landfills.
  • It improves soil structure and aeration of the soil.

Nutrient Composition of Eggshells

Eggshell comprises 95 % Calcium Carbonate (CaCo3), known as lime. An average eggshell contains approximately 2.2 gm of calcium. Other major nutrients in eggshells are 0.3 % Phosphorus and 0.3% Magnesium.

The shell also contains trace amounts of Zinc (Zn), Iron (Fe), Manganese (Mn), Copper (Cu), Sodium (Na), and Potassium (K). Together, these nutrients help improve the soil quality and enhance the soil structure, making it more fertile.

Can You Compost Eggshells In a Worm Bin?

Potato Peels In a Worm Bin

Eggshells can be used for vermicomposting as the worms love them. In addition, crushed shells act as grit to the worms and help grind their food.

Eggshell neutralizes the pH in the worm bin and helps your worms avoid problems like protein poisoning (a string of pearls). They also aid in the reproduction of worms, making them a great addition to your worm bins.

Risk of Salmonella in Compost

Salmonella bacteria reside on eggshells and may reach your compost pile if you throw the shells without washing them. It is dangerous, especially when using the compost for vegetables and fruits, as they can be consumed raw and enter your digestive tract.

To kill the salmonella, you need to generate heat in the compost pile. A high temperature like 140-160 degrees Fahrenheit will be enough to get rid of this bacteria. You can generate heat by turning the pile in regular intervals and adding 2/3 of high-carbon materials and 1/3 of nitrogen-rich materials.

Additional Tips For Composting Eggshells

Eggshells are among the nutritional ingredients used to nourish the soil and neutralize it. But before using them in compost, you need to follow specific guidelines. So here are a few tips for composting eggshells.

  • Wash the shells thoroughly to kill the salmonella bacteria and keep the animals away.
  • Break the eggshells into fine pieces as it will help to speed up the breakdown process.
  • Close your composting bin with a lid to protect it from animals and quicken the process of decomposition.
  • Maintain good aeration in the compost pile.
  • Maintain the temperature in the bin to keep the microbes active.

Other Uses of Eggshells in Garden

Eggshells in Garden

1. As a Liquid Fertilizer

Eggshells are rich in calcium and contain other plant nutrients like Phosphorus, Magnesium, Zinc, Manganese, Copper, Sodium, and Potassium. They act as organic fertilizer and help in plant growth.

These nutrients from the shells can be provided to the plants through a foliar spray. Follow this step-by-step process to make the liquid fertilizer from eggshells.

  • Collect a few eggshells and wash them.
  • Boil these shells and let them sit overnight.
  • Strain the liquid, fill it in the spray bottle, and use it as liquid fertilizer for plants.

Each eggshell adds approximately 4 mg of calcium. Add 2 cups of liquid fertilizer to the plants every two weeks. A pepper and tomato plant thrives well with eggshell fertilizer.

2. To Deter Crawling Pests

Crushed eggshells work as diatomaceous earth and can be used to deter garden pests like slugs, snails, cutworms, and crawling pests. When these pests come in touch with the crushed eggshells, the pieces cut their body, eventually making them dehydrate and die.

Simply crush the shells, sprinkle them over pest-infected areas and watch them work wonders for you.

3. As a Seed Starter Container

Eggshells can be used as seed starters for sowing seeds. Small and low-growing plants like thyme and succulents can be easily grown in eggshells. To use the shells as seed starters, follow these steps.

Seed Starter
  • Crack the egg and remove the yolk and white part.
  • Sanitize the eggshell by washing them or boiling them in water. 
  • Now poke a hole with a pin at the bottom of the eggshell for drainage.
  • Fill the shell with damp soil.
  • Sprinkle 2-3 seeds and cover them with the soil.
  • Place these shells in a holder and place them near sunlight.
  • Transplant the seedlings along with the shell when they reach the 2-3 leaf stage.

4. To Prevent Blossom-end Rot

Calcium deficiency may lead to blossom end rot in several plants like pepper, squash, tomato, melon, and marigold. Using eggshells can prevent the disease to some extent.

Crush the eggshells and bury them in the soil before planting the crop. You can also use powdered shells for this. Calcium slowly releases into the soil and aids in the formation of cell walls, thereby preventing blossom end rot.

Frequently Asked Questions:

Should eggshells be washed before composting?

Yes, it would be best to wash eggshells before composting as they are susceptible to Salmonella bacteria. Salmonella generally infects chicken and spreads to eggs. If such shells are put in the compost without washing, they can be transferred to the compost pile and might impact plant health.

How long do eggshells take to compost?

Because eggshells are made of mineral material, they take time to decompose. However, if you grind or break the shells into fine pieces, it will take 2-6 months for your compost to be ready. If you throw them directly into your compost bin without breaking them, the shells might take a year or more to decompose.

What happens when you bury an eggshell in your garden?

When you bury an eggshell directly in the garden without composting, it takes several months to years to decompose and slowly release its nutrients into the soil. These shells could only be helpful for plants grown in the next season. So, if you are planning to bury them in the soil, make sure to use crushed eggshells.

Can you put rotten eggs in Compost?

Rotten eggs should not be used in compost as the foul odor will attract pesky insects and animals. Moreover, the rotting might be due to any disease. If the infected eggs or eggshells are used composted, the infection will spread in your compost bin, later affecting your plants if the infected compost is used.

Can you compost boiled eggshells?

Yes, boiled eggshells can be composted. Eggshells are high in calcium, and boiling them releases only 0.2 percent of the calcium in the water. So composting these shells is ideal to utilize the remaining calcium and nutrients. Moreover, the water used for boiling can be used as a foliar spray for plants.

Can you compost cooked eggs?

Cooked eggs release an odor that attracts pests. So it is ideal not to add them to your compost bin. However, if added, make sure to put them in small quantities and bury them deep inside the compost pile.

Do the eggshell pieces in compost cause any problem?

Eggshells do not decompose as quickly as other food waste, and it can take years for them to break down entirely and disappear from your compost. However, using this compost is not a problem as it will release calcium and other nutrients into the soil when used.

So, now you know that eggshells can be turned into a nutritious fertilizer that adds organic material and improves the soil structure. So next time when you eat eggs, make sure to use their shells for composting.

Just like eggshells, avocado and avocado pits make good composting ingredients. So, if you are curious to know whether you can compost avocado pits or not, join us to learn more.