In my garden I find a couple of local cats (snuggly though they are), do like to leave little 'presents' in my borders and newly potted Japanese maples. I wondered what to do about it and not wanting to use anything harmful to the animals (though at times I was tested!), I remembered something I heard on BBC Gardeners World ... put down orange peel.
I have indeed put down some orange peel and it has worked a treat (cats do not like the smell of oranges). The only thing is you have to keep putting down fresh orange peel every couple of weeks and it can look a bit unsightly.
Then I hit on my own idea - I carefully took cuttings from a large spiky berberis and placed the bits in and around the plants. Cats aren't stupid and naturally stay clear of the prickles.