Introducing new snakes

[Garter_Gertie]

My two, Peepers and Jeepers (she says with PRIDE), are both yearlings but Jeepers is way littler than Peepers. They're doing fine, but they were housed together at DeKay's if not all the time at least off and on.

I'd try and keep sizes as alike as possible, just to be on the safe side. And sexes, too.

What kind of garter do you still have? Someone will chime in here that knows definitely, but I think ittiz Wanderings that tend to be the cannabalistic species of garters. I'd not put ANYTHING in with them they could fit in their mouth.

[Loren]

The only garters that I have heard of being cannibalistic are the Terrestrial(as Gertie said). This would include the coast, mountain, and wandering subspecies. Even they can be kept together with care, but should be same size and watched very closely at feeding time.
All other garters should be ok, but with any and all community snake cages, I reccommend similar sizes, and carefully observed (or separate) feedings.
I also recommend keeping all newcomers(and their cage products) separate for a period of quaratine, at least a few weeks, 2-3 months being ideal, so you can watch for health problems, including mites, which are not always visible when you first get an animal.
Almost everyone of us on this forum with large collections has probably been bit by that one at one time or another.

Personally, I have found it easier just to house snakes separately, but whatever works for you. When I used to keep my sierra, mountain, and valley garters together, feeding was a nightmare, and the mountain was always fighting with everyone else over the food.