Catnip is related to mint, prefers full sun, and will grow like a weed and take over your garden as luvedmabys says. (I just took up and trasplanted some very aggressive mint -- hard to get it all!)

If you don't want catnip (or any mint plant) to take over the garden -- experts recommned planting it in a pot in the ground so it can't expand.

I grew some catnip for Edwina in a pot a few years back. Although she likes the dried stuff she was indifferent to the fresh so I gave up on it! SHe loves to eat the dry stuff after she finishes "enjoying it."