[Lawtan]

Originally Posted by Gallagher

My cat loves tape, that would make him never leave the plant alone. Ever. Or at least until all the adhesive wore off.

I second Galla's suggestion...

...The main thing I know about training cats is that if you catch a cat eating a bird, if you ram a finger covered in bird down their throat, they'll avoid birds for a few years...or at least that's what my folk did when they caught the cat and a dead bird. Similar work with dogs. I am not certain of the other ramifications, and as one of them was a vet assistant, I assume they knew how to do it without harming the cat.
...either that, or I truly have been raised by two crazy people

My actual idea would be something that would give a little jolt if the cats got into the plants. Just something to deter them.