Nepeta mussinii is catmint. Nepeta cataria is catnip. Catnip is the one you want. It is a much bigger, softer plant than catmint. From a distance it almost looks like a nettle. Catmint has smaller silghtly harder leaves.
Hi Robyn. Don't know why Edd is suggesting letting the leaves dry on the plant. If you're gong to be discarding the stems anyway, why not just remove the leaves at the start? They dry out a lot more quickly then.
My plants are growing vigorously, so I can just pick leaves when I need them for indoor toys, and leave the plants where they are in the garden.
I have had to be a spoiltsport with my nepeta six hills giant, because the local cats eat it, attack itand lie down in it! I put a wire hanging basket over the last remnant of the original plant and managed to find a little piece of it to transplant to a safer place. I don't mind the cats visiting my garden and feel quite sorry to spoil their fun!