I put mine in the colder than the rest of the house half bath for a week or so but we just haven't had a good stretch of cold weather. I knew about the cold but not the light. Will be better about turning this light off earlier. Thank you for sharing! It's had blooms for the past several years, so I'm not too concerned. Fingers crossed for some cooler weather 🤞
Okay. I just spent five years waiting for mine (started from a cutting) to bloom. No dice.
Looked it up. Like poinsettias, they need 8-12 hours of darkness (no artificial light), starting in the fall, and temperatures of 50-60 F, for six weeks, in order to throw them into dormancy where they will bloom. Mine stayed in our family room where a space heater kept nostr:npub1uense4apn73tvh4u20tzlp6u72g4kdustzsm0k0sqy6yuwh5jxlsy97y76 cozy, and he always fell asleep on the sofa with the lights on, two or three lamps blazing all night. Poor cactus never got any cool, dark period of rest. Now it is in my office, where lights are off at night, it is in front of a north-facing window, and the temperatures in that room are much less like a hot-house. We shall see.

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Happy to share! It is a nice story how I got it. Mine came from a cutting at Chris’s Kitchen in Frito, Texas, near Lake Meredith. Chris had a bunch of them in her window there, next to where we sat for breakfast. I admired them, she said to take a cutting. I had no idea how to deal with them once they got growing.
I'm happy it took off for you. I had pinched a piece of this one ages ago and it never rooted. I'm a little better with plants these days so I might be able to root a piece now. My sister has one that has gorgeous peachy colored flowers I need to get. She has a nice covered area outside that hers thrives in and it bloomed like crazy. I have too many critters outside for mine 😒