I have to say I felt a little queazy at the thought of mixing corns and garters. I'm glad it's working for you, but I personally wouldn't want to chance it.
Like James my garters are mostly separated by subspecies too, though I kept the babies together and only put them into different tanks as some of them grew much faster and larger than others. My conncinus are quite big now, while the tetratanea are still very tiny. They have the company of one parientalis. I don't want them to cross breed and so will make sure they housed separately when they'd be old enough.
I would disagree with the non-social theory though. My garters always seem to interact in one way or another. They follow each other, dance together, wait for the cats by resting their heads on the door ledge then moving round comicly while the cats jump up and down, not being able to get them. Sometimes, I swear I can even hear them laughing at the daft cats!
