The Christmas Cactus (Schlumbergera x buckleyi) and the Thanksgiving Cactus (Schlumbergera truncata) are among the most popular houseplants sold during the North American holiday season. Despite their similar appearance and the fact that they are often mistakenly sold under the same common name, they are distinct species with clear differences. This widespread confusion stems from their overlapping bloom times and nearly identical care requirements, making visual identification challenging for the average person. Learning how to differentiate between these two holiday favorites comes down to observing specific details in their structure and their flowering habits.
Understanding Their Scientific Identity
Both the Christmas and Thanksgiving cacti belong to the genus Schlumbergera, which explains their strong resemblance and similar growth habits. They are native to the coastal mountains of southeastern Brazil, where they thrive not in desert sand but as epiphytes, growing harmlessly on trees or rocks in the humid rainforest canopy. Their common names are not rooted in botanical science but reflect the typical blooming period in the Northern Hemisphere when plants are brought indoors for the holidays.
The Christmas Cactus is technically a hybrid, Schlumbergera x buckleyi, resulting from a cross between S. truncata and S. russelliana. The Thanksgiving Cactus is the species Schlumbergera truncata, which is the one most commonly found in stores today.
Identifying Differences in Stem Segments
The most reliable way to distinguish between the two plants, even when they are not in bloom, is by examining the shape of their flattened, leaf-like stem segments, known as cladodes. The Thanksgiving Cactus (S. truncata) is characterized by having two to four prominent, pointed teeth or serrations along the margin of each segment. These sharp, claw-like projections are responsible for its common nickname, the “Crab Cactus.”
Conversely, the Christmas Cactus (S. x buckleyi) features segments with much smoother, more rounded, or scalloped edges. The indentations along the sides of the segments are soft and tear-dropped, lacking the distinct, sharp points seen on its Thanksgiving counterpart. The Christmas Cactus also tends to exhibit a more pendulous, or drooping, growth habit, while the Thanksgiving Cactus often starts with a more upright growth that eventually arches.
Distinct Flowering Schedules and Forms
The holiday names directly relate to the typical window when the plants naturally produce their vibrant, tubular flowers. The Thanksgiving Cactus generally blooms first, typically beginning in mid-November and continuing through early December. The Christmas Cactus blooms later, usually starting in late December and often extending its flowering period into January or February.
Beyond the timing, the structure of the flower provides another clear marker for identification. The Thanksgiving Cactus produces distinctly asymmetrical flowers that tend to grow horizontally or outward from the stem, with bright yellow anthers. The Christmas Cactus produces more symmetrical flowers that characteristically hang down or droop towards the ground. Its pollen-bearing anthers are typically a darker purplish-brown or pink color.
Cultivation Requirements
Both species are tropical epiphytes, sharing similar cultivation requirements for light, water, and soil. They require bright, indirect light and a well-draining soil mix that prevents the roots from becoming waterlogged. However, initiating their distinct flowering schedules relies on manipulating two environmental factors: photoperiod and temperature.
Both cacti require a period of short days and long, uninterrupted nights, ideally 12 to 14 hours of total darkness, for about six weeks to set buds. The Thanksgiving Cactus generally needs slightly cooler nighttime temperatures, around 50–55°F, during this bud-setting period. The Christmas Cactus uses cool night temperatures, typically between 55–65°F, in combination with the required darkness to trigger blooming.