When can I let my cats go outside?

get them spayed or whatever its called before giving them freewill to go in the garden, you could also get them collars with bells on so you can hear the distance they are away from you (I've had to do that with my 9 month yr old female cat) she's also killing birds aswell which is a shame but a good reason to have collars aswell to scare of the birds. yess you can buy cat leads aswell but I know their not big fans of being on a lead so make sure they don't take you for a run lol :P hope this helped.