How to Break Down Eggshells in Compost

Composting eggshells can be tricky because they often take a long time to break down. This tip will help speed up the process.

compost eggshells media

Grind eggshells into a fine powder to help them break down quickly in garden soil.

Photo by Jeannie Shank

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We have a short growing season in eastern Washington, so gardening can be a challenge. We have to make efficient use of the time we do have by supplying our gardens with the best soil possible. The natural soils here tend to be sandy, and they contain a lot of decomposed granite. As a result, nutrients wash out quickly, so we have to water frequently.

To improve the soil structure and provide organic material, many gardeners in our area are avid composters. However, eggshells in compost don’t break down well, so they’re a topic of frustration. Both of our neighbors have confessed to finally just giving up on composting eggshells and they now throw their eggshells in the trash. Tired of intact eggshells in my compost, but not ready to throw such a good source of calcium away, I found a method that works for me.

I air-dry eggshells on a cookie rack for a day or two and then throw them into my Vitamix on high. In a few seconds, the shells become a fine, granular powder that’s perfect for adding to the soil around tomatoes and other plants that suffer when calcium levels are too low. This eggshell powder is the easiest and fastest way I’ve found to use eggshells’ soil-enriching properties.


Colville, Washingtion