I’ve been at this for years and I have to say that there is no one magic bullet. What you can do is make it more and more difficult for them so that they give up and find an easier route to roam.
I have three steps for you to consider.
1) Secure and cat-proof your Garden –
by this I mean, block any easy ways in. This could be routed under broken fences that cats take to get in your garden. Lock an open gate. Put chicken wire over “open” fences. Put spikes on shed roofs or places they jump on. The trick here is to try and look at your garden through cats eyes and then catproof it.
2) Cat Spray and Citrus –
in the places where you are having particular trouble, and their entry routes, spray with cat repellent spray. Try and do this on a clear night. It can wash off easily in rain and you want them to get annoyed by the smell for as long as possible. If you don’t want to use artificial cat spray then try a mix of water and citrus juice (lemon or limes) they hate the stuff.
3) Get Planting –
plant lavender and thyme in areas where they definitely “do their business” or Coleus Canina if it is a relatively hot place. More on these plants later in the site – but the bottom line is, they do not like the smell of it hence they tend to avoid it. Remember cat’s have a more sensitive smell than you and I do, hence when they get a whiff of something they’d rather not – they tend to leave the scene.
4) Break out the sonic cat repellers! –
These are awesome. Put them in the area where those critters roam. In my experience, cats will only wander round by the sonic cat repellers about a meter or two. So if your garden is small you can cover a lot ground with two or three repellers. My garden is bigger than that so I tend to stick it into position, leave it a few days and then switch it to somewhere else in the garden that is also a problem…a few days after that I’ll switch back. It confuses them
The whole point is to make your garden as difficult as possible. Without being unfair to the neighbors – if your garden is difficult, inaccessible, and frightens them, they will go elsewhere. So remember cat proof it, spray it, plant it and break out the sonic cat repellers.