I don't use anything for snails.

i find my basilica's get savaged by cabbage moth and their little green caterpillars. I have used Dipel. It contains a naturally occurring bacteria and does not kill other insects. So the packet says. It is the only way i can get a crop of cabbages and broccoli. I used to try picking the caterpillars off the leaves every morning and night and squishing them and sometimes I would rub the dead ones over the leaves (you can make a spray of dead caterpillars all mixed up) but that was soooooo time consuming and they kept winning.