All About Christmas Cactus
Joe Gadbois, November 12, 2024
For generations, the Christmas cactus has been a staple holiday plant and an enduring favourite houseplant. Why does it continue to be so popular, and why might you want to jump on the Christmas cactus bandwagon? Let’s dive into the background of one of the most recognizable indoor plants.
The true Christmas cactus (Schlumbergera x buckleyi) is a hybrid developed in England in the 1840s. Today most plants sold as “Christmas cactus” in Canada are hybrids derived from the Thanksgiving cactus (Schlumbergera truncata), which does tend to start blooming slightly earlier, hence the common name. This creates a little confusion, but thankfully all the plants in the Christmas cactus group look very similar and grow under the same conditions. How can you tell the two apart? Thanksgiving cactus has pointed “claws” on the margins of its segments, while Christmas cactus has smooth, more rounded segments. There are hundreds of cultivars of both, and their showy flowers range in colour from pinks and purples, to red, to white, to shades of peach and yellow, depending on the variety (true yellow is rare). Sometimes plants in this group are collectively labeled “zygocactus” to avoid misnaming them.
These plants are epiphytic, meaning they grow on trees. Instead of growing in desert areas like typical cacti, they grow in jungles. Where desert cacti typically have a very thickened ball- or spear-shaped stem, the stems of jungle cacti are long, segmented, and flattened, eventually cascading over the edge of the pot. Yet despite a completely different habitat and growth habit, these are true cacti. Because of the difference in habitat, their care is more like that of orchids than of desert cacti.
Why are they so popular?
Christmas cacti were introduced to cultivation in the early 19th century. They were among the many plants brought back to Europe from South America by plant hunters. Over time, the plants became increasingly popular because they are so well-suited to growing in the average home, and their flowering season allows for a burst of colour during the winter months. Greenhouse breeding led to the many cultivars available today.
Because the plants are easy to grow and long-lived, individual plants are often passed down from generation to generation within families, and we commonly see plants that are brought in by third generation owners to be repotted by our tropicals team.
How can I grow my own?
Place in an area with bright light, but with protection from hot afternoon sun in the summer. An east window is ideal, but west or south windows can be used with a blind or sheer curtain. Provide as much light as possible during the winter months. You can also use grow lights.
The trick to getting these guys to bloom is to ensure their photoperiod (daylength) is shortened in fall and winter. Ideally, you would place them in a room that isn’t used in the evenings, so they will get only natural daylight from the window. Evening “light pollution” from interior lamps, etc. can prevent them from blooming. If you are using grow lights, they should only be on for 8-10 hours per day from October until blooming finishes. Cooler temperatures, especially at night, are also beneficial to induce blooming.
Any type of jungle cactus is sensitive to overwatering, but they also don’t like to be as dry as desert cacti. Water thoroughly when the potting mix is about 70% dry. When in doubt, don’t water. Pot in very well-drained potting mix. An example would be a mixture of 50% tropical plant potting soil and 50% perlite. Make sure your pot has drainage holes and is not oversized. There should be no more than 2 inches of space between the edge of the roots and the edge of the pot. Ideally, use a plastic grower pot with drainage holes and slip this into a decorative pot, making sure water is never allowed to collect in the bottom. You should repot into fresh soil every 2-3 years for best results; over time, potting mixes decompose and compact, leading to root rot. Plants left in the same soil for many years eventually go into decline and suddenly perish from rotten roots.
In terms of fertilizer, something with high phosphorus (middle number) such as 15-30-15, is ideal. I like to fertilize all indoor plants at ¼ strength every watering and flush the pot with plain water every fourth watering. After flowering, stop fertilizing until March.
How can I propagate my Christmas cactus?
While it’s usually too risky to attempt to divide Christmas cacti, they are easily propagated from cuttings. Plants grown from cuttings will be identical to the mother plant. Take cuttings that are three segments long and allow them to callus for up to a week. Bury the lowermost node (the point where two segments meet) in sphagnum moss or potting mix prepared with extra perlite, and make sure your container is not too large; 3 cuttings can be rooted in a 4” pot. Keep the moss or potting mix damp, watering when the surface has dried out, and keep the cuttings in a humid environment such as under a humidity dome. After a few weeks, check for rooting by gently tugging on the cuttings. Once they have rooted, begin acclimating them to lower humidity by venting the humidity dome rather than removing it entirely. After a week, the dome can be removed. Once the cuttings have rooted to the edge of the container, they can be potted on. If you root multiple cuttings in a container, it’s best to leave them together rather than separating them.
Related plants
Easter or spring cactus (Rhipsalidopsis gaertneri) blooms in spring and has smooth-edged stem segments and more open, daisy-like flowers. Orchid cactus (Epiphyllum spp.) is a larger plant with enormous flowers. Both can be grown in similar conditions to Christmas cactus.