Can You Compost Egg Shells? How to Make Use of Your Shells

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Whether you keep your own chickens or simply enjoy eating eggs regularly as a nutrient-dense food, the egg shells can collect quickly! If you already compost, you know the benefits of adding different nutrients to your soil, and you might be wondering whether leftover eggshells can be used profitably rather than being thrown in the trash. Can you compost egg shells? The answer is yes!

You do NOT need to throw those nutrient-rich shells in the trash can! Egg shells are a great source of calcium and are a great addition to your compost mix. And even if you don’t already have a compost heap, you can still use egg shells in other ways to support your garden and houseplants.

Can You Compost Egg Shells?

Absolutely! Egg shells are a rich source of calcium as well as other essential nutrients, and they’re an excellent addition to your compost pile. Composting your extra shells is a great way to not only reduce kitchen waste, but also add beneficial organic matter to your garden soil as a natural fertilizer.

The main way that egg shells boost soil health is by building contributing a high calcium content, which helps garden plants to build strong cell walls. They can also help to balance the pH of your soil and prevent blossom end rot. Lastly, they can support plant growth by providing pest control – deterring deer, cockroaches, and other crawling bugs.

Although they provide an important nutrient, one downside of composting whole eggshells (or eggshell halves) is that they can take a long time to break down – sometimes up to a year. For this reason, some people choose to break or grind their shells into smaller pieces in order to quicken the decomposition process. We’ll go over the process of how to compost your egg shells below.

Can egg shells have salmonella contamination?

Another concern with composting egg shells is that they could be contaminated with salmonella and then transfer that salmonella bacteria to your soil. How great is this risk? Well, the CDC estimates that about 1 out of every 20,000 eggs is contaminated with salmonella.

In other words – it’s quite low. And if you have or buy eggs from pasture-raised chickens, the risk is quite a bit lower.

How to Compost Egg Shells

There are numerous ways to re-use your egg shells. Don’t let those calcium-rich food scraps go to waste! Even if you don’t have a compost bin OR a garden, there are still other ways you might be able to leverage the benefits of eggshells to help you around the house or homestead.

egg shells and egg cartons in the kitchen

1. Add whole eggshells to your compost bin

This is the easiest way to make use of your shells. If you don’t have the time to crush your shells or otherwise prepare or use them, tossing them in your compost bin is certainly better than throwing them in the trash!

Keep in mind that uncrushed shells can take months to break down, so if you don’t plan to have your compost sitting for quite awhile, this could be problematic.

2. Crush or grind your shells

To aid in the composting process, it’s a good idea to break your shells into small pieces or even an eggshell powder by crushing or grinding them. Some of the best ways to do this include:

Crushing them with your hands
Using a coffee grinder to create a fine powder
Using a food processor to easily create bits of eggshell

You could also use a mortar and pestle, but this takes a bit more time. Pretty much any way you can think of to crush them into smaller eggshell fragments or even a fine dust will help to quicken the composting process!

3. Bake your egg shells (to eliminate the risk of salmonella)

If you’re concerned about the risk of salmonella, you can also bake your shells before using them. Since this is a bit more of a process, you may want to store up shells in the refrigerator or freezer until you have a significant amount.

First, wash your egg shells thoroughly and dry them on a paper towel.
Next, spread them on a baking sheet and bake at 200°F for 20 minutes.
After they’re cooled, use a coffee grinder, blender, food processor, or mortar and pestle to crush your shells. Note: If you plan to do this often, you may want to buy a cheap coffee grinder so as not to create too much wear and tear on nicer equipment.
Lastly, sprinkle them over your compost bin!

4. Fertilize your houseplants

Even if you don’t have a compost pile, you can use finely ground eggshells to boost the soil quality of your houseplants, especially if they’re lacking in calcium. Signs of calcium deficiency can include curling leaves, brown or yellow discoloration, rot, and slow growth.

To use egg shells on houseplants, it’s important to grind them into a very fine powder and only add a couple of pinches at a time to avoid disrupting the soil balance too much. In addition, it’s a good idea to use clean, dried shells, since any remaining bits of raw eggs can attract certain pests and insects. Definitely not something you want on your houseplants!

5. Use them to deter pests

Many people use crushed eggshells to reduce crawling pests in the garden such as caterpillars, snails, and slugs. The sharp edges of crushed shells can often deter these pests by creating a difficult landscape for them to crawl over – sometimes even acting like bits of glass. Simple sprinkle them around your plants to give it a try! You can use a food processor or grinder or just crush them in your hands.

Others say that eggshells are a great way to deter deer, since they dislike the smell of albumin (egg whites). If deterring deer is your goal, it’s better to leave your shells unwashed.

Others say that egg shells aren’t effective at deterring pests. Personally, we’ve had some success using them to eliminate slugs. The downsides are minimal, so I’d say it’s worth a try!

One caution to keep in mind: unwashed egg shells can sometimes attract rodents and small animals. If you have a problem with rats and other rodents in your area, egg shells could be a detriment to your garden.

6. Feed them to your chickens

If you have your own chickens, you can give them your leftover shells as a valuable addition to their diet. Chickens need calcium in order to lay strong eggs, and eggshells can help to provide this critical nutrient.

You should, however, probably avoid feeding your chickens shells from other flocks or from the grocery store, as this can pose the risk of contaminating them with different bacteria.

Some chicken keepers also worry that feeding eggshells to their hens will teach them to eat their own whole eggs. (Yep, some birds are egg eaters.) If you’ve noticed your hens pecking at their own eggs – or if they start doing so – you probably don’t want to feed them any more shells.