begining breeder

[drache]

Yes. They're painted keelbacks (Xenochrophis), not garters (Thamnophis).

painted keelback = xenochrophis cerasogaster
striped keelback = xenochrophis vittatus (the ones we have)
but definitely not garters - thamnophis - anything

[Stefan-A]

They're all painted keelbacks. It's the same as with garter snakes, the original garter snake is T. sirtalis. That's what the word sirtalis means; "Like a garter". Thamnophis, by the way, is derived from the words for "bush" and "snake".

Simply calling them keelbacks isn't recommended either, because that refers to the genus Rhabdophis.

[drache]

They're all painted keelbacks..

you probably have better sources that I do, Staphan
the source I used listed the painted keelback as a separate species from the banded or striped Keelback. It also listed seven other species with various common names (Boulanger's, chequered, yellow-spotted, etc)
All of these are referred to as keepbacks.
There is also a painted keelback among the tropidonophis species, but I couldn't find that common name among the rhabdophis species
of course my actual experience of any of these is nil

[Snaky]

Maybe an addict is an idea?

[adamanteus]

To add to that...

Look at the weather records for the area where your snakes originate. Is there a cooler, rainy season? If so, what temperatures are recorded for that period of the year?

Then your brumation should mimic that temperature.

To add a little more....
Sometimes the cue to trigger breeding behaviour can be even more subtle in some species from warmer climes. Something as obscure as the arrival of a particular food species can trigger changes in behaviour. Probably not relevant to Xenochrophis, but I thought I'd mention it.