I grow catnip in my flowerbed out back. Each of my cats reacts differently to it. Trevor rolls in it on the floor and gets all mellowed out and sort of dreamy-eyed. Andy attacks it and gets all hyper and turns into a dynamo! I used to watch a vet by the name of Dr. Bernie on TV (...wonder where he went, now that I come to think about it) and he said that catnip usually doesn't affect cats before the age of two, but both of mine didn't take that long. Logan, it's easy to grow and it spreads and its a perennial....comes back each year!