For many of us winter consists of long months filled with cold, grey days where we can only dream of warm, green spring days filled with flowers. However, there are some plants that grow indoors which brighten our lives by blooming during the holiday season. The Thanksgiving cactus (Schlumbergera truncata) and the Christmas cactus (Schlumbergera bridgesii) are fall and winter blooming houseplants available in a wide color variety including; red, rose, purple, lavender, peach, orange, cream and white.
These natives of Brazil grow naturally as epiphytes among shady branches in the rain forests. During normal night length conditions Thanksgiving cactus will bloom around Thanksgiving, approximately 1 month before Christmas, if room temperature is around 68 degrees Fahrenheit flowers can last 6 to 8 weeks. This fortuitous bloom time means these cacti will commonly be found for sale during the winter holiday season. The easiest characteristic to identify Thanksgiving cactus from Christmas cactus is the shape of the flattened stem segments (phylloclades); Thanksgiving cacti have 2-4 saw-toothed serrations at the margins while Christmas cacti have rounded margins. Neither plant produces true leaves, so photosynthesis occurs in the phylloclades.
Holiday cacti grow best in light shade. They will benefit from full sun in the fall and winter, but full summer sun will cause plants to appear chlorotic. Short day lengths, 8 to 10 hours, and cooler temperatures in the fall are essential for both species of cacti to set flower buds, but they will not survive outdoors when temperatures are 50 degrees or lower. There are several key factors to producing a good bud set on your Thanksgiving or Christmas cactus, these include:
- Daytime light needs to be very bright.
- Adjusting the photoperiod, if possible, for long nights; approximately 14 hours. Begin long nights in early September and continue for 6 weeks.
- Temperature should be between 60 and 68 degrees Fahrenheit (staying as close to 68 as possible for maximum flower production) throughout the fall.
- For extensive branching and more terminal flowers, pinch back stems in June.
Water indoor cacti when growing medium feels dry to the touch. These plants are highly tolerant of underwatered growing conditions during spring and summer, but during winter it is very important to neither let the media become waterlogged nor overly dry. Holiday cacti actually thrive when somewhat rootbound, and will only require repotting about every three years, if then. Potting media needs to be well-draining and able to remain aerated. A mix with 60-80% soil and 20-40% perlite is desirable for healthy growth.
Thanksgiving and Christmas cacti suffer from a few common issues, but they can all be somewhat easily remedied. Many cacti will drop unopened flowers, this may be due to a sudden change in temperature or light or the potting medium drying out. If flowering is short or stunted, the necessary long night may be being interrupted, street lights, car lights or indoor lighting may be the cause. The only major disease affecting holiday cacti is root rot, which can be averted by avoiding overwatering.