I have never witnessed a catfight over a catnip plant though. To learn about growing catnip, read Growing Catip from our Herb Gardening topic area. To learn more about catnip and why it works the way it does, read The Joys of Catnip from our Cats topic area. Apartment cats should have some form of grass to chew on or they will chew your houseplants. You can also cut a circle from lawn grass and put it in a pot to bring indoors.
Cats chew grass for roughage.
They need a little to get the hairballs out. Normally a cat who eats a lot of grass will barf it up within the hour, although not all grass is regurgitated. It has nice grey-green leaves with a ferny outline, and yellow flowers. The smell is acrid and repels cats. Since cats don't really care about the smell of the place they are pooping in, this does not really work for poo-zones in your garden.