How to Use Eggshells in the Garden

Do eggshells really benefit the garden?  Since eggshells are 95% calcium, and calcium is known to be good for plants, does this mean that eggshells are good for plants?  Well, there's a right way and a wrong way to use eggshells in your garden. The most common method is unfortunately the least effective, but after you read this article, you'll know how to use eggshells in a way that's more effective than using agricultural lime!

Short Answer

It's true, eggshells can be a great source of calcium for your plants but only if prepared properly.  Eggshells act the same as using limestone which helps boost vegetable crops by increasing soil alkalinity.  This is important if the soil in your area is known to be more acidic.  

How does calcium work in plants?

Calcium is essential for root development, stem growth and foliage.  The plant uses calcium to build cell walls making the plant more rigid. The plant also uses calcium to create cellulose and starch.

Symptoms of calcium deficient plants.

Symptoms of calcium deficiency in typically appears on new growth. If the leaves are distorted or discolored between the veins, cupped leaves, premature blossom bud dropping, weak or dying stems, these is a sign of calcium deficiency.  In tomatoes specifically, the bottom of the fruit turns brown and becomes leathery in texture. This is called blossom end rot.  

How NOT to use eggshells in the garden.

Simply crushing up eggshells and putting them on your soil is useless.  The eggshells take forever to break down and will not transfer their calcium into the soil.

Not in Compost! Many people think the composting process will break down the shells but unfortunately this isn't true.  If you've been putting crushed eggshells in your compost, take a close look at the finished product, you'll notice that the shells haven't broken down.  

How to properly use eggshells in the garden.

First you need to start off by sanitizing the shells.  Put them on a baking sheet and in the oven on 200 degrees Fahrenheit for 30 minutes.  This is going to kill any lingering bacteria and salmonella. It'll also make the shells easier to grind up. 

Use a blender, coffee grinder or mortar and pestle to grind up the shells into the finest powder possible.  Doing this will allow the powder to bind to the soil, becoming readily bioavailable to the plant roots and altering the soil pH. It's important that you mix this into the soil between 4 to 10 inches deep. Use about 2 TBSP of powder (approx. 5 shells) per plant.

 

It's not realistic to do this process every time you use eggs. A tip is to wash off the shells immediately after cracking them and put them somewhere to dry. When you have a significant amount saved up, go ahead and make your powder.  The best part is, this stuff never goes bad so just save it for next season.