I have tried dried/used teabags and coffee pods soaked in jeyes fluid dotted around the garden borders/flowers to stop them digging up. It seems to put them off, but you need to change them regularly and it doesn;t stop them messing on gravel areas unfortunately. (use Jeyes with care obviously)

My next door neighbour is well impressed by a sonic device he got online and has fixed to the wall. We have a lot of problems with cats by us!!

you can buy "GET OFF MY GARDEN" gel at vets or pet shops. I circled my car with it to stop my kitten getting in the engine and it worked. But you have to repeat regularly. Or citrus fruit peel is quite good

hi there i use pepper on my pebbled,area and underneath the trampolean area wheres theres bark once a week i now have no problem with cats and it does not bother the kids. this may help you and it does not hurt the cats.

T&M sell a plant called Coleus Canina - also known as the Scaredy Cat Plant, which apparently scares off dogs and foxes too. It looks pretty, with blue flower spikes, but smells foul, particularly when touched. I do not speak from experience, only reading knowledge. I find a loud cat-like spitting noise directed at the cat with open mouth will scare them off. Obviously it has to be repeated and, of course, you have to catch the cat on your property, but when we first moved here we were over-run by feral cats who lived in the barns. Several 'spits' later and they tend to steer clear of our bit of village! ;oD