Every year at this time I’m confronted with supermarket displays of Christmas cactus (Schlumbergera x buckleyi), usually heavy with buds, and of course I always buy one. I’ve known gardeners who inherited Christmas cactus from their grandparents, large enough to require a table dedicated to supporting them. This has not been my experience and, in fact, I hold the indoor record for speedy dispatch of this plant to the compost bin.
One year, I Christmas purchased a Christmas cactus with ethereal white blossoms with deep raspberry markings. After I brought it home, the flower buds swelled, two of them opened and the rest fell off. I realize it’s asking a lot of an understorey tropical forest cactus from the coastal mountains of southeastern Brazil to adapt to winter living room conditions in Ontario. But it does seem cruel that a potentially gorgeous plant arrives with dozens of flower buds intact and then dumps most of them within 10 days. As you may guess, this was my attempt to displace blame to the plants, to the greenhouse personnel who produced the plants or any circumstance apart from my own treatment. I don’t like it when plants fail on my watch.
Christmas cactus care
Christmas cactus are easy plants to grow, and most problems are related to flowering. They need a slightly dry, cool and dark resting phase in autumn to produce flower buds. Similar to the poinsettia, the forest cactus clan requires 12 hours of complete darkness each day starting in mid-September for about six weeks, with absolutely no artificial light during the night periods. That means putting the plant in a closet for 12 hours every night, and bringing it out into a southeast or northwest window for the daylight hours. During these weeks allow the soil to dry slightly (but not dry out entirely), and the room temperature should be in the cool range around 15°C, and lower (in the closet) at night. When buds are evident along the leaf tips, the plant can remain in the window for display, and watering should be increased. Keep the soil moderately moist (but not wet) and provide forest-like air humidity to retain flower buds.
Greenhouses have all sorts of equipment and personnel to easily maintain these conditions, but domestic houses fall far short of the tropical forest conditions. I don’t know anyone who plans their days and nights around moving the Christmas cactus in and out of a closet. But I do know gardeners who have some success initiating flower buds in unorthodox ways. Some put the plant outdoors in June in a shady location, and don’t bring it back in until the end of October (or sooner if nights threaten to be frosty), providing water and feeding twice with a balanced fertilizer (such as 10-10-10). By then it’s had a summer growing phase and an early autumn cool period, during which watering in September and October is cut back to half the summer amount. Perhaps this is enough to trigger flower buds; it also helps if the plant is somewhat root bound, in a tight pot.
Other gardeners do almost nothing, allowing the cactus to remain in its permanent indoor position the full year. Sometimes a dark paper bag is used to cover the plant for 12 night hours (not complete darkness, but sort of dim). If light isn’t too bright in the room, the plants sometimes produce flower buds on the back, or dark side, positioned away from the window. It’s all a matter of the plant’s ability to accommodate our lax and inattentive care, while striving to propagate its species by producing flowers. Unfortunately, we’ve crossed them up again with hybridization, which produces the lovely supermarket colours at the expense of fertility. What’s a plant to do, but struggle on in a world of commercial plant production?