Neal, I tried the Beer traps, it didn't work for me. Kathy has it right - in the evening I would place Apple and Potato slices in such a way that the slugs can hopefully climb underneath them and can be collected the next morning. And you might be surprised what else you find on them besides Slugs, if those plants had been outside.
I also would remove any old bark mix, Slugs love to get into those. And pots with rims are a great hiding place for them.
