A few years ago I wrote a post entitled Things I Learned About My “Christmas Cactus.” In that post, I explained how I’d learned that the so-called “Christmas cacti” that you find in stores around the holidays are really Thanksgiving cacti (Schlumbergera truncate).
I also learned that while darkness can make the cactus bloom, temperature is even a stronger force causing this plant to want to reproduce. That made sense given the way that my cacti blossom. I never worry about light and darkness yet they bloom every year.
But right now I have proof that temperature really is a strong factor in getting this plant to blossom.
I have a pot with four different Thanksgiving cacti in it. I have it hanging on a curtain rod in a west-facing window. The plant blossomed well around the holidays and since then, I’ve basically forgotten about it. I’ve watered it when I think of it, but that’s all the care it’s received.
One day when I was watering I was surprised to see that half of the pot was filled with buds while the other half wasn’t. What caused this strange phenomenon? Temperature. The half of the pot with buds was the part closest to the window. We’ve had a cold winter so those stems have been kept very cool, especially at night. The part of the pot that had no buds was the side facing the room.
The other interesting thing is that whatever factors cause the cactus to bloom, they appear to stay localized. Branches of a cactus that were close to the window are blooming while other branches of the same plant that were facing the room aren’t blooming. That seems to show that whatever causes the plant to bloom isn’t some chemical that translocates throughout the plant. Instead, the factors that cause the plant to bloom only affect the areas that are exposed to the cooler temperatures.
While days are getting longer and the intensity of sunlight is increasing, the cool temperatures close to the window were enough to get this cactus to re-bloom – well, at least half of it. I will admit it’s a little strange to see a pot with only half in bloom but it just goes to show that when it comes to getting Thanksgiving cacti to bloom, temperature trumps all!