We got down to 5 last night. Yeeeoow, for here it's cold! Supposed to be windy tomorrow so we'll have some major windchill.
I always plant stuff that can survive one zone colder than where I am. So now I go for z.7 plants and haven't lost anything that I've put in. I don't zone push, it'll eventually catch up with you.
I am worried about my 3 agaves that survived the Big Freeze of '11. We had some good rains several days ago and everything had a good drink. We really needed the water but now with this cold I'm hoping the agaves will be OK.

Yeah, I hear you about being cautious in terms of zone designations. We had -7 Monday night where I live... I'm still a zone pusher, and I've got plenty of things in the ground that are rated to zone 8 and 7 that made it through our -23 low last February, however, I'm much less willing to take a gamble now.

I wish I could say that February's record lows won't happen again, but with this early December cold snap, I'm starting to believe forecasters who expect some extreme bouts of cold continuing over the next couple winters.

Good luck with your agaves!