My neighborhood is inhabited by no less than 10 stray cats which several of the neighbors feed and otherwise care for. Last year, I had the issue of the cats being fascinated by the loose, aerated soil in my garden, and they thusly proceeded to dig in it and use it as a litterbox. Occasionally, they'd kill one of my plants either by peeing on it or knocking it over in their digging zeal, and all last year, my garden smelled to high heaven like cat poop.
I tried barriers. I tried hot pepper flakes. I tried soap flakes. I tried to convince my wife to let me take them to the pound (to no avail). None of these seemed to deter the cats, and eventually (after having to replace a third of my tomato patch due to casualties) the plants were big enough to withstand peeing and being hit, and I learned to live with the smell.
Well, this year they're doing it again, and I'm fed up. Do you have any tried and true (non-lethal) ways of deterring cats from digging up my garden? I swear, I'm pondering a way to make weak-force mousetraps or something to give them the equivalent of a ruler against the knuckles.