Don’t throw away those eggshells, instead use them in your garden. The next time you bake (or use your sun oven), place your eggshells on a cookie sheet. Baking the eggshells sterilizes and enables you to dry the membrane inside the eggs so it is easier to crush up the eggs. You can use your blender to make a fine powder allowing for easier absorption by the plants. Using the eggshell power is fine yet you are likely to discover that your soil has plenty of calcium for your gardening needs, unless you wish to super-charge high calcium greens like spinach and swiss chard even more. After baking use your hands to crush the eggshells. You can also toss the baked eggshells in compost tumbler, yet you may find that they didn’t get crushed enough for gardening. Once crushed to a consistency that you like, add to compost and combine well. Now you have great potting soil that drains well. Eggshells can also be mixed directly into the soil. Crushed eggshells provide added calcium as they decompose. Mulching with a 2 in. cover requires serious egg consumption but even small coverage helps. Research of other eggshell uses in the garden includes benefits such as a deterrent for snails and slugs and feed for wild birds (who eat the shells to gain calcium for laying their eggs). Although we have not confirmed this in our own garden, others have expressed these benefits.
This video shows the steps and includes use of the eggshell enhanced soil in planting and growing pilea microphylla and myrsine.