How To Use Eggshells In Compost And The Garden

Humans are very wasteful creatures, especially when it comes to the kitchen.

Take, for example, the humble eggshell. Like our used coffee grounds (and filters), eggshells are immensely useful in the garden, yet we just chuck them in the bin while preparing breakfast.

But there’s a bit of a trick to using eggshells in the garden, as they can perform more than one function, depending on how you prepare them.

Here’s a quick and easy guide on using those eggshells well so you won’t end up walking on them regarding your garden’s health.

How To Use Eggshells in Compost And The Garden?

There are three basic functions of eggshells in the garden:

Disease control
Pest control
Nutritional supplement

Here’s how you can apply them for each task and just what they can do.

How To Initially Prepare Eggshells?

The usefulness of eggshells can differ based on how you harvest them.

Hard-boiled eggs would result in pure eggshells, which might only need an hour or two of air drying if you shelled the eggs under running water.

However, when shelling raw eggs, you’ll have a bit of slimy residue left on the shell.

This will require additional time to dry before the shells are ready for use, although you can crush a few and chuck them into your worm bin as-is.

Also, remember that a raw eggshell can contain pathogens such as salmonella and should be set aside from your food surfaces to dry.

Eggshells As Pest Control

When it comes to pests, especially slugs and snails, the only thing more effective is salt (which is not so good for the garden).

To use eggshells as a form of pest control, grind them up with a mortar and pestle or by hand so that they become small fragments.

Next, sprinkle them around your at-risk plants to create a minefield of death for any soft-bellied critter who dares try to munch on your garden.

Various studies have found that eggshells won’t degrade easily, and the larger the fragments, the more resistant they are to breaking down.

As a result, eggshells used in pest control will have very little nutritional value for your plants.

Composting Eggshells

As mentioned, you can use raw, crushed eggshells in vermicomposting.

Simply put a small amount in with your other worm food.

The eggshell’s coarseness will aid digestion and be processed into a more calcium-rich batch of worm castings.

Another option is to ad the crushed eggshells directly to your compost pile.

Raw shells work better; the smaller the shell, the faster it decomposes.

If you crack your eggs one-handed, the resulting halves could take years to break down, so crushing or grinding is highly advisable.

Also, keep in mind that composting crushed eggshells will result in little to no direct nutritional benefit, although it can help neutralize acidic soils.

Therefore, you should also avoid using eggshell-enriched compost around acid-loving plants such as blueberries.

Avoid using eggshells in tandem with agricultural lime, as this could result in alkaline soil.

The Nutritional Value Of Eggshells

When using eggshells for a nutritional supplement or disease control, they must be prepared differently than for pest control.

If properly prepared, the chemical composition of an eggshell becomes available to your plants.

This composition includes:

95% percent calcium carbonate
0.3% percent phosphorus
0.3% percent magnesium
Approximately 4.4% percent of other elements

The eggshells also contain trace amounts of essential nutrients such as copper, iron, magnesium, and zinc.

As a bonus, it helps to raise the pH of acidic soils, making them more neutral.

Eggshell meal is rated at an approximate NPK of 1.2-0.4-0.1, making it a poor choice as a standalone fertilizer but much better when used as a nutritional supplement.

The Value Of Eggshells In Disease Control

The calcium found in eggshells is crucial for strong stems, like for strong bones in animals.

Not only does this mean improved growth, but in many garden vegetables such as peppers, tomatoes, and squash, the added calcium has been found to prevent blossom end rot.

It can also prevent other diseases caused by calcium deficiency, such as apple cork spot.

Advanced Preparation Methods

We’ve discussed how eggshells can be used in compost or as a disease and pest control, but what about as a supplement?

Here are a few more ways to get the most out of your eggshells while boosting your garden.

Eggshell Starters

One genuinely innovative use for intact eggshells is as a starter pot.

For those who crack eggs one-handed or use the tap method to cut the top off, the shells make for a perfect starter “pot” for many plants.

You’ll want to boil the shells to sterilize them, making them a safe growing environment and creating shell tea (more on that later).

Just add some starter soil into the shells and sow the seeds.

You can try cucamelons, several succulents, tomatoes, or practical kitchen herbs/companion plants such as mint or thyme.

Knock the top off of the egg carton and use it for a shell holder.

Note that with fast-growing plants such as tomatoes, you’ll have to transplant to a pot soon after germination, although herbs will often be able to enjoy the shells longer.

Powdered Eggshell

While crushed eggshell has next to no nutritional value for plants, the Alabama Cooperative Extension has found that powdered eggshell is more effective than agricultural lime as a source of calcium.

To create the powder, just throw your dried eggshells into a coffee grinder (preferably not the one you use for making coffee).

You can sprinkle some powder into the hole before transplanting seedlings for an early calcium boost.

Additionally, you can add a teaspoonful as needed over the soil to boost calcium levels.

Just be warned that too much of a good thing can be bad, so try not to add more eggshells than necessary to maintain healthy calcium levels.