Tomatoes need calcium to achieve their full flavor potential. When planting tomato plants crush up (to powder) about 4 or 5 egg shells and put them in the bottom of the hole. Then plant tomato on top. They'll provide calcium and prevent blossom end rot.
keep shells in open container in fridge. When full, crush shells into small bits and sprinkle around base of plants. Sharp eggshells will deter slugs, snails, and other bugs from nibbling on garden and add touch of calcium to soil.