I just can’t throw away eggshells in the garbage even living in a small apartment with no possibility of a compost pile. So I save them. Leave them in the oven when I bake something so they get dried out and
I use them like perlite in my potting soil. So far so good. I also hate throwing out used coffee grains. So I store them in plastic containers and use sparingly in my potting soil. The acid coffee should balance the alkaline in the eggshells. Here is an interesting article on many uses for eggshells including eating them, and I won’t go that far.
