Keep Pets out of Flower Garden

I've tried many methods to keep my cats from digging up my flower garden in early spring, from cayenne pepper sprinkled in the soil (doesn't work) to adding broken sea shells (also doesn't work).

This year I decided to lay down a short garden edging fence we were no longer using around a tree. It prevents them from digging into the ground, but doesn't stop the plants from growing through the openings.
Yay!
Success!