Break down and buy some slug bait, I use stuff made by " king" and it contains a chem called Metaldehyde wich attracts the slugs and pretty much kills them on the spot, this stuff in no way affects your soil, BUT ITS toxic it will kill animals so you have to keep the stuff covered and watchs for peoples pets, it would be a bitch if some one found out you killed their cat protecting your weed plants from slugs, i have 30 cats and not one ever got into the stuff , There is a non toxic version of the stuff, made by a diff company, but its crap and its not as afeective, so i hope i could help you, trust me its worth killing any slug that comes near yer plants.