I have two Christmas cacti, just cheap garden center types, each about 5 years old. They have always bloomed in October for a few weeks, and then not bloomed for another year. I deduced that they were "Thanksgiving" cacti, but was still troubled that their blooming period was so short. So this year I decided to pay more attention to them and put them in a south facing window around December 1. They got decent light during the day, and the air temp is about 20 deg C during the day and 10 deg C at night. I watered them once a month. Around Feb 20 I noticed that they were starting to form the red growing tips that have historically led to flowers, and on March 6 they started to flower. One is now in full bloom and the other looks ready to follow suit. Now, I know that the "Christmas" in "Christmas cacti" is not to be taken literally, but I find this somewhat surprising none the less. Am I doing something wrong? Something right? Has random chance taken hold? Incidentally they are right beside 10 epipyhlum cacti whose seeds I planted two years ago, which I have always treated as I am now treating these ones and which are behaving as I expected for that environment: right now they are basically dormant. I live in Vancouver near the botanical garden.
I think mine sometimes bloom more than once per year, or maybe vary the timing. They must not be completely photoperiodic, as we don't cover them at night and they are near (but not under) lights that are on at night.
They will bloom multiple times if conditions are right. Some bloom up to 4 or more times. Cool and/or dark nights induce bud set. Tom