by Don Janssen, Extension Educator
Christmas Cactus Bloom
Photo by V. Jedlicka
The exotic-looking flowers of holiday cacti can be a spectacular addition to the holidays.
Plants that have been in your home tend to bloom around Thanksgiving or Christmas in response to winter's short days. Plants brought into the home ready to bloom may drop their buds rather than burst into flower, however. Flower buds may fall off without opening if temperatures are too high -- above 75 degrees Fahrenheit. Sudden changes in temperature or light levels and overwatering can also cause buds to drop.
To guard against temperature fluctuations, wrap your holiday cactus carefully before you take it from the florist's or the garden center to your car and don't leave it sit in the car while you run other errands -- take it straight home. Then place it where it will get plenty of bright light but won't be exposed to hot or cold drafts, and water it when the soil surface feels dry.
In the greenhouse, holiday cacti are programmed to bloom at Thanksgiving, Christmas or Easter by manipulating day length and/or temperature. Plants exposed to 9 hours of daylight and 15 hours of darkness beginning in September will set flower buds. Temperatures between 50 and 59 degrees Fahrenheit will also stimulate flowering, regardless of day length. Temperatures below 50 degrees Fahrenheit will inhibit flowering, however, as will temperatures above 85 degrees Fahrenheit.
In their native Brazil, holiday cacti grow in pockets of plant debris in trees or in decaying humus on the ground, so they need a light, humusy growing medium and containers with holes for good drainage. Potting in heavy mineral soil or a container without provision for drainage may result in overwatering, root rot and plant death.
Though most people lump all holiday cacti together under the term "Christmas cactus," Christmas and Thanksgiving cacti are two distinct species: Schlumbergera x buckleyi and S. truncata, respectively, and the Easter cactus is Hatiora gaertneri. To tell them apart, study the shape of the leaf-like stem segments. In Thanksgiving cacti, the edges are sharply toothed or jagged; in Christmas cacti, the segments are smaller and have more rounded lobes. Also the Thanksgiving cactus tends to grow more upright, and the Christmas cactus is generally more pendulous, or drooping. The Easter cactus is more like the Christmas cactus, with flat, segmented shoots, but its joints are saw-toothed rather than rounded.
Flower colors in holiday cacti range from white through pink, rose and coral to red, as well as golden yellow. A large, established plant may bloom beginning in mid-November through most of the winter and even produce a few blossoms again in the spring or early summer. The rest of the year, it's a sturdy, interesting houseplant that thrives with minimal care.
University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office