We call them Christmas cactuses, but that’s not strictly accurate. According to Wikipedia, Schlumbergera is a small genus of cacti with six to nine species found in the coastal mountains of south-eastern Brazil. Most plants sold in the horticultural trade are cultivars of either the Truncata or Buckleyi group. S. truncata cultivars generally flower a bit earlier than those in the Buckleyi group. They are more properly called Thanksgiving cactus. As you can see, mine are in full bloom nearly two months before Christmas, and these blooms will not last more than about three weeks. Truncata plants have more pointy teeth on the stem segments. Their flowers tend to be upright or horizontal and the pollen is yellow. Buckleyi cultivars have more rounded stem segments and bloom a bit later, making them closer to a true Christmas cactus. The pollen is pink and, unfortunately, the blooms tend to be downward-facing.
In their native Brazil, these plants are epiphytes, growing on trees, rather than in soil. There they are called Flor de Maio (May flower), which is when they flower in the southern hemisphere. If you’ve ever wondered, the trick to getting your Schlumbergeras to rebloom is to ensure they have twelve hours of daylight and twelve hours of darkness. Mine spend the summer outside and only come in when frost threatens, so they enjoyed equal periods of day- and night light during the fall equinox. Although they are true cacti, they will tolerate more water than most cacti. Just don’t leave them sitting in water! And keep them out of direct light. They like diffuse light, so a north or east-facing window should work well.
Gardening at Last 