Hello, I'm a newbie on here and to gardening in general. Today I bought some catmint on a whim and before planting thought I should look up some info. I can't find anywhere how deep the container for the cat mint needs to be? I have a container that is 40cm wide and 18cm deep - is that enough? Unfortunately the plant tag doesn't provide which type of catmint it is, but all catmints seem to grow pretty tall. Does this mean it needs a container that is at least 30cm deep?

Any help would be much appreciated!