Experts and BHG readers answer.
Cats in garden and flower bed
There are spray repellents you can try. I know the Messina company sells one that you should be able to find at most garden centers. Otherwise, there's not a lot you can do, short of having animal control remove the animals with live traps. If you have a small area with just containers you can protect them by covering the surface of the pots with stones, but if this is an entire garden, there's no easy way. I'd try the repellents to see if they work, but I'd also contact local animal control.