Xmas cactus

The beginning of flowering in my greenhouse is much retarded, maybe because of the tremendous outside cold we’ve experienced (Two nights in a row of -15 F (-26 C))  My heaters kept the greenhouse at its usual nighttime temperature of 40, but the daytime temperature, caused by natural heating, has been low.  We barely got above 10 F outside on one of the days.  The greenhouse was below 50.  There are a few things blooming, and almost blooming.

This plant is inside the house in a south-facing bump-out window.  It’s not supposed to be blooming, but there is always some volunteer in any population that marches to a different drummer.