Posted: 04/10/2014 at 16:09
You could keep it potbound and on the windowsill for now. I've grown it for a few years, and it sometimes survives the winter outdoors, but not always. It also sometimes self seeds and grows again in the same patch, but again, not always, probably because cats love it too much and nibble it and roll all over it before it gets established and grows again.
I grow it in pots in the greenhouse, and plant out when its established, into an area of the garden where I'm happy for the cats to enjoy it. It over winters ok in the greenhouse and is ready for the garden in spring, as well as a fresh source of leaves for the cat in winter when there would be none still growing outdoors.
My seeds were originally Mr F's rather than T&M, but they look like the same variety, Nepeta Cataria.