Crushed eggshells can also prevent damage as these critters do not like to move across sharp objects.
Simply crush up empty eggshells into relatively small pieces and scatter them around your plants.
Not only is this a cheap way to stop slugs and snails but it has the added benefit of enriching your soil as the calcium is released into the ground as they decompose.
Broken nutshells and sharp horticultural grit can be used instead of eggs shells to form a barrier as these sharp pieces act in the same way.
