Plant it in higher ground where you can cover it in the winter if you're having freezing temps. Older plants can take a frost/freeze if dry, but they don't like it. If you plant it close to a house wall, so much the better (ambient warmth).

Lullaby This is a site that will hopefully help.
http://tastylandscape.com/2013/04/24/a-very-tasty-cactus-cereus-peruvianus/
I live in Shreveport and I would guess that if it was outside this past winter you would be hunting for a replacement for your plant. To wet and way to cold for a long time in Shreveport.
Best
Bob

Hopefully we will not see this kind of winter again. It killed several trees in my yard in zone 6. Good advise to plant high for drainage and a cover wrap for those very cold nights that you might run into. I know zone 9 is no problem and they take more water than most.
Good luck.
Also don't plant all out side. Try one first. Just in case.
Stush