Using eggshells is an easy way to add extra nutrients to your tomato plants and deter slugs at the same time. As the eggshells break down, calcium is released freely into the soil. The calcium helps your tomato plants grow and prevents blossom end rot. You can use raw eggshells on tomato plants but hard boiled eggshells are easier to prepare.
Place the eggshell pieces into a wire mesh strainer and rinse with warm water. Pull away as much of the slick inner lining of the shells as you can. Let the excess water drain.
Spread the shells in a single layer over paper towels to air dry. Large shell pieces can be turned as needed to help them dry.
Place the dried shells into a Ziploc bag, press out the air, and seal it. Place the bag on a flat surface and use a rolling pin to crush the shells into smaller pieces.
Spread approximately 1 cup of eggshells in a circle around the base of each tomato plant. Use the cultivator to gently work the shells into the upper layer of the soil while being careful not to disturb the root system of the plant.