How to kill snails
Use Sluggo, a non-toxic snail bait. Snails eat a pellet of corn meal and iron phosphate, and go away to die. The bulk of it is corn meal. The active ingredient is iron phosphate, or fertilizer. There is no chemical residue. It dehydrates snails because they would need to drink a lot of water to dilute the iron phosphate they ate.
Since snails get all of their water from their food, and can not drink, they just stop eating and walk away, never to be seen again. The stuff is non-toxic to dogs, birds, etc since the overall amount of iron phosphate is low, and they can drink water. I don’t how this product would be considered outside the bounds of ‘organic’ gardening.
Copper strips will stop snails in their tracks. The only problem is that you may need of lot of it, and you may only be trapping the snails inside the bounds of your metallic pen. Beer in pie plants will attract them. You can squish them, drown them. or eat them, your choice.
Nightly patrols about an hour of two after dark with a flashlight can help. Handpicking each night can help reduce the population of hidden snails. You can find them coming out to feed, and can destroy them any way you choose.
Another option, I want out early in the morning found them crawling out on top of my plants and dropped them into hot water. I also moved flats and plants where they were hiding inbetween, and grabbed them as well. I am getting less each year. Norma