I've been keeping eggshells in a bowl in the back of our fridge for weeks... I wanted to try this natural fertilizer in my garden, so I kept collecting and collecting. Egg shells are a great additive to any garden soil because they're high in nutrients, mostly calcium, and are guaranteed to breakdown. I would really love to have two plants of exactly the same health, environment, etc. to use for an experiment. Put eggshells in the soil of one plant and see if it grows better or faster or bigger. Here are a few tips for adding eggshells to your own garden, big or small!
1. Rinse your eggshells! You don't want to attract unusual critters or plant any salmonella bacteria.
2. Simply crush the eggshells with your hands, being careful not to cut your fingers on the sharp edges. You could also use a mortar and pestle if you really wanted to. Or just a rock, I suppose.
3. Eggshells will keep away slugs and caterpillars. They don't like the jagged edges!
4. The smaller the better. The smaller the shell, the faster it will decompose. (I left mine pretty big though.)
5. Fold the eggshells into the soil. This helps speed up decomposition, as well. (I haven't done this yet!)
I sprinkled the shells around everything... hydrangeas, day-lilies, calla-lilies, begonias, etc. But I was mostly curious about my how tomato and basil plants would fare with a little extra kick. I'll let you know how they do!