Slugs and snails can do major damage to tender garden plants. They usually feed at night and hide during the daylight hours. Snails and their shell-less relatives, slugs, are mollusks and are related to clams, mussels and oysters. To make it harder for snails and slugs to become established, clean up garden debris, where they like to hide. A barrier strip of copper foil will also protect your plants, as snails and slugs are electrocuted when they come into contact with the metal.
Copper tape is also available, with adhesive on the back for easy installation.
Prevent trailing plants from growing over the copper and creating a bridge for the snails to cross. The sharp fragments of diatomaceous earth puncture the body of the mollusks and eventually kill them. Make sure you choose diatomaceous earth designated for garden use. You must keep diatomaceous earth fresh. Once it gets wet it loses its sharp edges and its ability to deter slugs and snails.