Cats need a soft surface in which they can dig – sand, compost, newly dug earth, or even bark chippings under shrubs. If you don’t supply this in your own garden, they have to find it elsewhere – either in your neighbour’s garden or even further away. This may mean crossing a road or even passing through the enemy territory of an aggressive local cat. It can be very stressful for them.
So make a latrine for the cats in your garden in a place that suits you. This means the cats are less likely to use the rest of the garden. The location should be somewhere secluded with places to hide on the path to it from the house. This means your cat shouldn’t have to cross a huge expanse of lawn or decking to get there but should be able to get there via shrubs, trees, plants and plant pots which give some cover.
Dig a hole in a dry place – – under a shed, under a hedge, under shrubs – and fill it with gravel. Over the gravel put a thick layer of dry sand. Put some cat soiled litter there to encourage use. You will have to scoop up poop daily and urine must be washed away with a hose pipe – remembering that the latrine will not be used if it is soaking wet. In a dry climate, this means hosing daily. If it has rained for hours, probably doesn’t need doing it – use common sense. If you don’t clean the latrine enough, it will smell.
Never withdraw the indoor litter tray. You will need this if the cat is ill, old, tired or being attacked by neighbouring cats. But if you make a nice place outside for them they will probably use the indoor litter only rarely.
Some people put a litter tray in the garden shed or somewhere under cover. A big rabbit hutch might be useful for this. One disadvantage, however, is that you forget to clean the tray often enough, ie daily. The other disadvantage is that neighbouring cats may use it resulting in very dirty litter.