And here's a close up of a flowering shoot so you can see the "frozen spinach" look of the foliage. I don't know exactly just how cold it's been so far for sure, but I know it's at least been down to 16°F within the past week and blooms were still looking fresh and undamaged when the temperatures warmed back up afterwards.
Here's that same shoot close up later in the day when the temperature went above freezing again. The ground is still frozen underneath the surface, so I think it's having a hard time sending water up to the thawed out parts, but even so looks pretty unfazed. I'll try to get another picture once it's been above freezing long enough to thaw the ground too.