Getting your Christmas Cactus to Rebloom
The Christmas cactus (Schlumbergera) is a short-day plant, that is to say, it blooms only when there is less than 12 hours in the day. So flowering is initiated from September 22 on. Except when we light our homes in the evening. Since the plant requires no light whatsoever after 6 pm. Even a single ray of light at the wrong time can cause its bloom to abort. What to do?
When I was a beginning gardener, “they” used to tell us to put the plant in a closet or cover it with a cardboard box late every afternoon and to put it back in the sunlight every morning. Right! As if anyone would actually remember to do that without fail. After all, one forgetful moment over 2 months and – bam! – no flowers!
Here’s a much easier way. Place the Christmas cactus in a room that is not used at night, but is very sunny during the day: a guest bedroom, for example. Now remove all the light bulbs in the room and place your plant by the window. Since you removed the bulbs, even if you accidentally enter the room in the evening and try to turn on the light, you won’t be able to. So, your Christmas cactus will necessarily get the short days it needs and begin to bloom.
If you can’t do that, trying simply putting your Christmas cactus behind another plant or some other sort of barrier, anything that will keep artificial light from reaching it at night. That should work too.