I went through a phase where I was baking a lot — sourdough, quiche, meringues that collapsed — and I looked at my trash can one Saturday and realized half of it was eggshells. It felt wrong. Something that came out of a chicken should not go straight to a landfill.

Turns out eggshells are 95% calcium carbonate — the same stuff in limestone, antacids, and garden lime. Here is what I started doing with them.

Garden Supplement

The classic use and still the best one. Calcium deficiency causes blossom end rot in tomatoes and peppers — those ugly black spots on the bottom of the fruit. Eggshells add calcium back to the soil.

But here is what the internet gets wrong: whole shells decompose incredibly slowly. I buried intact shells in a raised bed once and found them still recognizable six months later. You need to crush or grind them. A coffee grinder turns them into powder in seconds. Work this into the top inch of soil before planting.

If you are adding shells to a compost pile, crush them roughly. The smaller pieces break down faster than whole shells but you do not need powder for compost.

DIY Scouring Powder

Baked eggshells ground to a fine powder make a gentle abrasive cleaner. Mix with a little baking soda and use on sinks, tubs, and stained mugs. It is coarse enough to scrub but soft enough that it will not scratch porcelain.

I keep a small jar under the kitchen sink for stubborn tea stains in mugs. Works as well as commercial powder cleansers and costs nothing.

Seedling Starters

Crack eggs carefully near the top so you keep most of the shell intact. Rinse, poke a small drainage hole in the bottom with a needle, fill with potting soil, plant a seed. When it is time to transplant, crush the shell gently and plant the whole thing — the roots grow through the cracks and the shell decomposes.

This is also a great project with kids. My nephew thought it was the coolest thing that a plant could grow out of “breakfast trash.”

One Thing to Skip

Some blogs suggest eating eggshell powder for calcium. Technically you can — but the calcium carbonate in eggshells is not well absorbed by the human body in that form. A calcium citrate supplement will do far more for you. Save the shells for the garden.