i like the idea of growing catnip together with your plant. One good thing is that having another the catnip may prevent you from over fertilizing as it will compete for the nutrients. Can be beneficial to some who have a tendency to over fertilize. plus your cats really will love it. If you want to grow another plant they will love try cat grass. You will have to try hard to keep your cats away from the plants. good luck
The night I set it up I didn't notice one of the cats following me to the crawl space, and she ended up locked in there all night.
If it wasn't in a cage the whole box would've been a mess.
And I'm pretty sure I am over fertilizing... brand new store-bought soil plus the flower food = the catnip is looking pretty burned (holes, sloping, etc) but my girl is still doing good.
If there are any interesting new developments when I check it out tonight (day 15) I'll post some pictures, if not it'll probably be about day 23 or so that I'll have an actual bud shot...