We recently learned that the Christmas cactus at the library may be fifty years old. It is very large and has thick woody stems in the pot. This year the cactus bloomed for Christmas, and since I have a very small, young Christmas cactus that did not bloom, I decided to learn how to get it to bloom for next Christmas
Fortunately, the book I was currently reading, A Field Guide to the Familiar: Learning to Observe the Natural World by Gale Lawrence, has a short chapter on Christmas cactus. She says that the scientific name for the cactus is Schlumbergera bridgesii. If you search the Internet for this, you find that there are other species of plants called Christmas cactus with different scientific names. I am going to stick with her designation.
Ignoring for now the interesting information about Christmas cacti that Lawrence has in her book, I'll only quote her paragraph on getting the cactus to bloom for Christmas:
.....you must slow down your watering in September, giving your plant just enough water to keep it from shriveling and allowing it to rest for six to eight weeks. If you have a room that doesn't get used after dark in the fall, you can station the resting plant there. Otherwise you'll have to cover it each evening to assure it at least thirteen hours of uninterrupted darkness. If you can't control the light, perhaps you can manipulate the temperature. At a cool 50-55°F (10-13°C), the Christmas cactus will produce buds no matter how much light it gets.
I moved my cactus into our bedroom because it is unheated. I did not control the light and I did not moderate the temperature — and I have no blossoms. Next year I will do the right thing.
Gale Lawrence retired from UVM and developed two web sites. They have not been updated since the early 2000s, but are worth looking at. She also has links to other natural history books and sites. Visit her at The Naturalist's Almanac and Book of Days and at The Vermont Almanac. Lawrence is the author of four books and two of them are at the Barton Public Library.