How to Compost Eggshells & Benefits

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In Brief: Composting Eggshells

Eggs are a great addition to any compost pile. Here we will show you how to add eggshells to your compost pile. They are so full of vitamins and nutrients, not to mention calcium!

Many of us love eggs for their nutritional content. Not many people know, however, that the shells have multiple uses in the garden, as well.

They are a great source of nutrients for your compost pile, allowing you to have a healthy and thriving garden.Keep reading if you want to know what you can do with eggshells to keep your garden thriving.

Benefits Of Putting Eggshells In Compost

For many years, eggshells have been recommended by experts as an amendment to containers and soils. One particular reason why they can be used and they are so valuable is because the eggshell is rich in calcium.

For example, if you add a minimum of 6 eggshells into the hole where you plant tomatoes, you can reduce the blossom end rot of the fruit. Others add eggshells in order to add calcium to their compost.

Not many people may know that eggshells can be used to fight off pests. Surprisingly, these shells help deter pests that include snails, slugs, cutworms, and many other crawling pests.

When you use crushed eggshells, there is an effect similar to diatomaceous earth. In other words, when the crawling pests cross the area on which you spread crush shells, these shells make small cuts in the crawlers.

As a result, the pests dehydrate and die.

Possible Issues From Putting Eggshells In Compost

One main issue that frustrates many gardeners is that eggshells do not really break down. Most people simply have given up on putting them in their compost.

If you have done this before, there is no doubt that you noticed the pieces of eggs in your pile.

Some people have even found eggshells in their piles after many years. Those who used halves of eggshells noticed very little difference later on.

Coarsely ground eggshells, or those which are crushed by hand, are most likely to remain whole without decomposing. This is because they are made of calcium carbonate, the main aim of which is to protect the egg inside.

Dr. Jeff Gillman published a book titled The Truth About Garden Remedies in which he did an interesting experiment. He boiled one eggshell and let it sit in the same water for 24 hours.

Then, he analyzed the minerals in the water and found about 4mg of calcium and potassium. One eggshell has approximately 2,000mg of calcium.

Through boiling and soaking, only approximately 0.2% of the calcium was released. The question is – if boiling water did not impact the eggshell structure, how can you make rain and soil water decompose it?

How To Compost Eggshells

As explained above, eggshells are tougher than we might expect. However, we can do a few things to ensure that our soil benefits from the nutritious calcium inside the shell.

The main trick is to grind the eggshells as finely as possible before using them. The smaller you can get the particles, the better it is for the compost.

A study conducted in the Alabama Cooperative Extension used coarsely ground (crushed by hand) eggshells and finely ground eggshells (fine powder). They concluded that the coarse eggshells were not making any difference, while the fine powder performed just as if you added pure calcium.

You can use a coffee grinder to crush the shell into an efficient fine powder. Once you do this, you can spread the powder on your compost pile, around the landscape and garden, or right into the tomato-planting holes.

If you do not have a coffee grinder, there is another option. You can boil 10-20 eggshells and leave them to soak overnight.

The next day, strain the eggshells and use the water, as it contains pure liquid calcium that is transferred from the eggshells. You can use about 2 cups of this solution per plant for two weeks.

Here’s a video with some great tips about using eggshells in your compost heap and garden:



Are eggs dangerous when used in compost?

The dangers of using raw eggs are present whenever we use them. As a result, you can either wash them thoroughly before adding them to compost, or you can only use the eggshells from hard-boiled eggs. Any type of cooking, including boiling, kills any bacteria and other pathogens that might be present on raw eggs.

Why is calcium important for the soil?

Calcium is needed in soil structure because it enhances soil fertility. It helps to retain a flocculated clay, ensuring appropriate aeration.


All in all, using eggshells to make compost may have more benefits than you can think of.

All you need to do is make sure that you turn them into a fine powder before adding them to the pile.