Slugs are one of the worst creatures to have with marijuana seedlings, one slug can kill multiple plants overnight. It seems like out of all the surrounding vegetation, the slugs end up going for the mj plants, slugs are attracted to marijuana the most, they must think its delicious, probably a delicacy lol. Ive heard of many methods over the years, two of the most common being the beer and copper wire trick, slugs can cross copper wire, unless you spend a bunch of money on wide copper metal and place that around your plants buying spindly copper wire will not do anything. The slugs are only attracted to the beer because of the yeast in it, the beer goes bad within a couple days and you have to change the beer almost every day. I have also heard of people putting down dry substances around the perimeter of the plant, the theory being, slugs have to produce to much slime in order to crawl over something so dry making it impossible to penetrate. Sand and wood ashes are supposed to be to good for protecting from slugs. My way is a little different, I like to do things the fast way, and the fast way, and the way I recommend is go down to your nearest hardware store or garden shop and buy a 500g or so box of slug bait pellets. Its a box that contains a bunch of tiny pink pellets, all you have to do is simply spread it in little piles in different areas near your plants. I can guarantee you that this stuff works wonders, it will stop literally EVERY slug that ever had a mission on munching on your plants. A 500 g box of pellets is only about ten bucks and can last an entire season, depending on how big of a garden space you have. You only need to re-apply every 2-4 weeks, but the seedling stage is when the plants are most vulnerable. So Quick before another bastard slug kills another plant, go buy some slug bait and sprinkle!!! lol hope that helps, happy toking.