My Christmas cactus always blooms early, sometimes before Thanksgiving. Is this normal? How can I keep it blooming longer?
It’s possible the plant you call Christmas cactus is actually a Thanksgiving cactus – yes, there are two slightly different varieties. Look at the stem segments: if the margins have two to four sharp serrations along each edge, the plant is Schlumbergera truncata, the botanical name for Thanksgiving cactus, which blooms slightly earlier. If the segments are more rounded, the plant is S. bridgesii, Christmas cactus. That’s the one more likely to bloom in December or later.
Both are photoperiodic plants – they respond to the change in proportions of light and dark, and begin to form buds as days shorten and nights begin to get longer. They also thrive in the same conditions: bright light and a moderate amount of water, and a dose of balanced fertilizer every now and then. (In her book The Complete Houseplant Survival Manual, houseplant expert Barbara Pleasant suggests once-a-month feeding in winter.)
Christmas and Thanksgiving cacti are generally easy-care plants. They benefit from being outdoors during the summer, but bring them inside when nighttime temperatures drop to 40 to 50 degrees. Place them out of bright sunlight, then when buds begin to form, bring the plant into the bright light.
One other thing to know: when the plant is full of buds, it sometimes seems to resent being moved, so once it’s placed in a good spot for winter, try to avoid moving it. “Once plants begin blooming, they may drop their blossoms if exposed to any kind of stress,” Barbara Pleasant writes. A stable environment should keep those blooms going longer.
They are easy to share. Schlumbergera propagates easily from stem cuttings, and a plant can live for several years, even a decade or two.