I don't think that kale would freeze at 23F. I could be wrong.

I has been 14 or below for three of those nights.

I would definitely blanch it before freezing it. Freeze-thaw cycles release enzymes that can quickly cause deterioration of flavor, even in a deep freezer.

Is it all soft and wilted, collapsed and blackened? If so then you wouldn't want it anyway. If not then it hasn't been frozen/damaged regardless of what your temps have been and likely it won't be. Kale grows all winter with no problems even in the far north.

But if you want to harvest it then yes, it will need to be blanched before packing for the freezer to destroy the spoilage enzymes.

You can learn more about the process over on the Harvest forum here as it is the food preservation forum.

Dave