Hi backacre,
to ATP.
I think you are talking about Kleinia mandraliscae. It can be hardy down to the mid teens, 15° if kept on the dry side. I put mine on the deck, under the roof, for the winter. We get so much rain here during winter, with lots of freezing for short periods of time. Would love to see photos of yours.
Here is a link to our database.
Blue Chalk Sticks (Curio talinoides var. mandraliscae)