So I made seedling pots last week, out of halved toilet paper rolls, to hold catnip seeds, and some flowers too. Today I decided, not being an expert at all, that the little ones were big enough to move into larger pots! I don't know if you're supposed to keep the rolls but I did, thinking it might make them more comfortable to have a familiar place in their new home.
And they seem popular already - see the paw far on the left? :D