Try using crushed eggshells to prevent snail or slug attack. This method seems to work as hungry gastropods don’t seem to like slithering over the sharp edges.
Collect used eggshells over a period of time. Let them air dry for a day or so. Crush them up fairly time, I find a pestle and mortar does the trick best.
Put a layer of the crushed eggshell around the base of any plants that are susceptible to slug or snail attack. Don’t forget to put some around the support canes too.
Top up the layer of shell after a few days of watering.