Last year my Christmas cactus was slow to bloom, and I think it was because there was a new lamp on a timer in that room and my plant was getting several hours of artificial light each evening. Christmas cactus plants begin setting buds after they receive about 12 hours of darkness for 6 or more weeks.
This year I was very careful to limit the light in the room after sunset even if it meant shrieking when anyone would flip on the light switch. My plant is blooming like crazy—right on schedule—and I only have a few bruises from stumbling around the dark for the last month or so.
This cultivar (sorry, no clue about the name, I received a cutting as a gift) has such beautiful pink and white flowers that I decided I wanted a second plant. In late spring I snipped off a section of stem and kept it in a vase of water until I could see little roots forming. It took about a week. Then I stuck the stem in a pot and let it fend for itself.
In less than 6 months the plant has branched out nicely, and it’s even going to bloom soon.
These plants must be pretty tough because I appear to be breaking most of the rules with great success. Christmas cactus plants prefer bright indirect light, but mine sit in direct sun in a south-facing window all year-round and they don’t seem to mind a bit.
Apparently you should also avoid placing them in drafty areas or they might get stressed and drop their buds. Where are my plants located? Above a heating vent, of course. I’ve never noticed any bud-drop.
And finally, Christmas cactus plants prefer a light, well-draining potting soil and are happiest when root-bound. At least I’m doing something right.