I have a bunch of CIDPs and two nice Medjool date palms. I have one that is about a seven gallon size and had been in the ground for over a year when we hit 19 degrees and also 21 and 22 this past winter.

I had just thrown a blanket over it. Anyways, it came through with absolutely no damage at all. Same for my bigger one, about a thirty gallon size. Also wrapped blankets w/christmas lights around my two Medjools. No damage at all.

The year before, we hit twenty and the Medjools had basically no protection. That year they looked burned...but made an extremely quick recovery (like 2 mos). That was wierd as if the fronds turned back green. They are not quite as hardy as the CIDPs.

Also, my brother in law has an established thirty gallon CIDP that saw 15 degrees with NO protection in zone 8b. It was almost completely defoliated, but it's already pushing out new fronds.

I also have some Phoenix Roebis, but forget about those. They can't even handle frost, at least not when young.

I'll try to post some pics soon. I hope this helps.

Most Phoenix dactylifera are hardy to about 17 although there is some variation with each variety. All my varieties did well in the 07 freeze with only a few having minor tip burn/yellowing. I had down to 12 one day and 2 more days down to 14. But that also asumes some frost protection in the form of running warm irrigation watter to help add heat to the whole garden.