Christmas Cactus, Easter, and Thanksgiving Cactus is a small genus of cacti called Schlumbergera with 6-9 species found in the coastal mountains of south-eastern Brazil.
Plants grow on trees or rocks in habitats that are generally shady with high humidity and can be quite different in appearance from their desert-dwelling cousins.
The modern genus Schlumbergera was created by Charles Lemaire in 1858. The name commemorates Frédéric Schlumberger, who had a collection of cacti at his chateau near Rouen in Normandy.
Lemaire placed only one species in his new genus which was a plant discovered in Brazil in 1837 which had been named Epiphyllum russellianum by William J. Hooker. Lemaire renamed it Schlumbergera epiphylloides (under the current rules of botanical nomenclature it should have been called Schlumbergera russelliana, which is its current name).
Lemaire noted the similarity of his Schlumbergera epiphylloides to a species first described as Epiphyllum truncatum by Adrian Hardy Haworth in 1819 but did not accept that the two species should be included in the same genus.
In 1890, Karl Moritz Schumann created the new genus Zygocactus, transferring Epiphyllum truncatum to Zygocactus truncatus.
Although he later placed it back in Epiphyllum, abandoning Zygocactus, the generic name Zygocactus continued to be widely used.
In 1913, Nathaniel Britton and Joseph Rose followed Lemaire in keeping Schlumbergera russelliana and Zygocactus truncatus in separate genera.
They also transferred the Easter cactus to Schlumbergera as S. gaertneri, initiating a lasting confusion between these two genera.
In 1953, Reid Venable Moran placed both Schlumbergera russelliana and Zygocactus truncatus in the genus Schlumbergera. Other species were added later by David Hunt, including those formerly placed in Epiphyllanthus, to form the modern total of six full species and a number of hybrids.
Most species of Schlumbergera have stems which resemble leaf-like pads joined one to the other and flowers which appear from areoles at the joints and tips of the stems.
Two species have cylindrical stems more similar to other cacti. Recent phylogenetic studies using DNA have led to three species of the related genus Hatiora being transferred into Schlumbergera, though this change has yet to receive widespread acceptance.
Schlumbergera and Hatiora have long been confused. Species in the former genus generally have tubular flowers that are zygomorphic, while those in the latter have actinomorphic flowers with inconspicuous tubes.
DNA data shows that the two genera are not monophyletic and the three species in Hatiora subgenus Rhipsalidopsis have been transferred into Schlumbergera, although this change has not been universally adopted.
Common names for these cacti generally refer to their flowering season. In the Northern Hemisphere, they are called Christmas cactus, Thanksgiving cactus, crab cactus, and holiday cactus. In Brazil, the genus is referred to as Flor de Maio (Mayflower), reflecting the period in which they flower in the Southern Hemisphere.
In the wild, the species of Schlumbergera grow either on trees (epiphytic) or on rocks (epilithic) and can form sizeable shrubs with woody bases; a height of up to 4 ft has been reported for one species (S. opuntioides). ‘They are leafless, the green stems acting as photosynthetic organs. The stems are composed of segments, which take one of two forms.
In most species, the segments are strongly flattened (cladodes), being made up of a central core with two or more rarely three “wings”.
Special structures characteristic of cacti, called “areoles”, then occur at the ends of the segments of the stem. In two species the stems are less flattened, more cylinder-shaped, and the areoles are arranged in a more or less spiral pattern all over the segments.
In both cases, the areoles, which may have wool and small bristles, are where the flower buds appear.
The flowers either hang downwards and are almost radially symmetrical, as in most species, are held more or less horizontally with the higher side of the flower different from the lower side which is radially asymmetrical or zygomorphic.
They are also seasonal and bloom in fall, winter or spring, giving them their name of Holiday Cactus – Thanksgiving Cactus flower in the fall, Christmas Cactus around the Christmas holiday and Easter Cactus in spring.
In those species whose flowers are held up, their angle with the horizontal is relatively constant and is characteristic of the species. Each flower has 20–30. The outer tepals are those closer to the base of the flower are short and unconnected. The tepals spread out or curve backward.
The inner tepals are those towards the tip of the flower are longer and become progressively more fused together at the base to form a floral tube.
In some species, the difference between the outer and inner tepals creates the appearance of a “flower within a flower”. The flowers produce nectar in a chamber at the base of the floral tube.
This plant (Schlumbergera bridesii or Schlumbergera truncata), although known as cactus, is really a succulent, having its origins in the tropics. Like the poinsettia, the Christmas cactus needs to follow a pretty strict regimen in the fall in order to bloom at holiday time. In order for the plant to form flower buds for holiday blooms, it needs extended darkness for at least four weeks prior.
In late September or early October, place the plant in a dark room or keep covered (under a box or bag works fine) for at least 12 hours a day. When the tiny buds appear (after three to four weeks), the light/dark schedule can cease.
As the buds get bigger, move the plant to its “display area”, avoiding extreme temperature or lighting changes. Continue to water and feed while budding and blooming.
Water your Schlumbergera cactus when the top inch of the soil is dry. Always take into consideration the climate and time of year. If your cactus is outdoors in a hot, dry climate, you might need to water every two to three days, especially if the plant has been in the sun. If you keep the cactus indoors where it is cool or humid, it might need water only once a week. Water less often during the fall and winter to help stimulate blooming.
Over-watering is a problem for the Schlumbergera cactus just as it is for other kinds of cactus. Over-watering can lead to fungal rot diseases such as white rot and can cause leaves to drop. White rot disease is easily recognized by the white spots on the leaves.
Because Schlumbergera cactus is not a desert cactus but a tropical one, it cannot take as much under-watering as other cactus species. If a Schlumbergera cactus does not receive enough water, it will wilt and its flower buds will drop. Unlike a desert cactus, a Schlumbergera cactus cannot tolerate completely dry soil. To avoid problems with fungus, avoid overhead watering.
Temperature and Humidity
The Schlumbergera cactus does best in a humid environment. This is particularly important for gardeners living in a dry climate or whose homes have a dry indoor climate. The easiest way to provide humidity is to place a tray of water near your plant. The water evaporates into the atmosphere, providing the needed humidity. Another way is to put gravel in a dish and fill with water before placing the potted plant into it. Misting your cactus with a spray bottle can also provide humidity.
The Schlumbergera cactus prefers bright indirect sunlight. If growing them indoors, protect them from direct southern or western sun exposure.
They do best in warm temperatures, 70 to 80 degrees Fahrenheit, and will form buds when evening temperatures are 50 to 55 degrees.
Throughout the winter, try to keep nighttime temperatures around 60 to 65 degrees. Avoid placing Schlumbergera cactus in cold drafts and keep them away from sources of hot air such as heating vents or fireplaces.
Fertilize in the spring as soon as tender growth appears. Use a liquid houseplant fertilizer every two to three weeks up to a month before the first blooms are expected to appear.
Problems With Schlumbergera
Schlumbergera cactus can be prone to bud drop, so avoid extreme environmental changes. Keep them away from drafts or heat sources (vents, fireplaces, or televisions). Avoid letting the plants get too dry between waterings.
The stems and roots can rot if the soil holds too much water, so be sure to use a well-drained potting medium and water only when the potting medium begins to dry out.
Be sure to keep your Schlumbergera cactus away from artificial light during the night from October through December if you want it to bloom during the holiday season.
Is It Poisonous?
In the wild, birds would eat the fruit and spread the seeds of Schlumbergera cactus but the fruits of this plant are not considered edible by humans. However, they are not classed as poisonous and it is not listed on the poisonous plant’s list.
There have been reports of dogs vomiting after eating a Christmas Cactus, however, each case has other reasons the dogs could have been sick.
Most reasons are the dog ate or drank something else during their naughty moments of acting out. I can just tell you that we have had tortoises eat this plant with no issues at all.