Slugs-Again

Today I saw a big fat slug halfway between the carport and my greenhouse. I picked it off and stepped on it. Then I put a wide layer of diatomaceous earth at the door to the greenhouse. I've been carefully watching my seedlings in the greenhouse because the slugs will eat the primary leaves and just leave the little stems. I've sprinkled the dirt with diatomaceous earth. A friend said she used slug bait and shoveled dead slugs. But most of the slug bait says not to use it near food plants. So I'm limited in where I can use it. I have copper somewhere that I got last year. I have to try to find it.