Botanical name: Schlumbergera species (formerly Zygocactus). Family: Cactaceae
Common names: Christmas cactus, crab or Thanksgiving cactus, Easter cactus
Range: Tropical jungles of South America, grows on trees (epiphytes)
Of all the holiday plants that are on display this month, my favorite is the holiday cactus. Because they have been heavily hybridized among themselves there is much confusion in the garden books and nursery trade alike. Here's the latest on how to tell them apart. The Christmas cactus, S. russelliana (also sold as S. bridgesii and Zygocactus truncatus-both outdated names), has bright green, smooth scalloped-edge joints that measure one and a half inches long. Flowers may have many petals, are long-tubed and three inches long, unless it is a modem hybrid, which have more compact flowers than the old-fashioned ones. The branches droop gracefully, especially when in bloom. On S. truncate, Thanksgiving or crab cactus, the stem joints are longer and narrower and are sharply toothed (hook-like appendages), with two large teeth at the end of the last joint. Flowers are short-tubed with spreading, pointed petals. Easter cactus, S. gaertneri (also known as Rhipsaidopsis gaertnerii) droops less and has sharp tipped, upright or horizontal flowers.
Still confused? More confused? Give up? Luckily, these plants are very easy to care for so your best bet is to forget what kind it is and decide what color you want! Over the past few years breeders have increased the translucent color range from red and pink and now includes orange, yellow, white, salmon, cerise, and purple. Blooms usually last about a week but the display can often last a month. I worked in an office where a holiday cactus thought it was Christmas all year long! My co-workers would pour their cold, day-old coffee in the pot and it bloomed nonstop. Schlumbergeras love rich (leaf mold), acidic (coffee), porous (perlite) soil that is kept evenly moist, and bright indirect light. You may keep them outdoors spring thru fall provided they are in a shady spot. To initiate flower buds stop fertilizing in September and keep them in a cool environment (nighttime temperatures at 50-55°) with 12-14 hours of uninterrupted darkness every night for at least 4 weeks. Little buds will form and then the absence of light is no longer critical. My grandmother kept her very old and huge holiday cactus outdoors during the fall and the cool nights induced the biggest and most intensely colored flowers I have ever seen.
Schlumbergeras - a holiday plant that's just not for the holidays anymore!