Tip of the week. Eggshell compost. To keep your plants thriving or help new plants grow simply sprinkle finely crushed eggshells around your soil. Eggshells are full of calcium and as they break down they act like a natural fertiliser, providing plants with valuable nutrients. Eggshells can be used in potted plants as well as your garden to deter slugs and snails. Try sprinkling coarsely crumbed eggshells around your plants - the sharp edges will stop them sliding past and feasting on your garden.