My Christmas cactus started blooming a few days before Christmas, which is a first. The poor plant has been neglected for years, in part because my cats, particularly one of them, attacked any and all house plants. A ficus tree was quickly destroyed 15 years ago, but the cactus managed to survive by being consigned to marginal areas like attics and basements in the winter and being put outside in the warmer months.
There is a family story that this particular cactus is cutting of a plant that lived in my great- grandparents house in Hartford, Connecticut. This may actually be true; they can be very long-lived and I certainly have no recollection of buying it in a store*. They are also popular because they don’t require very much maintenance to survive, although getting them to actually flower at Christmas can be a bit of work.
The so-called Christmas cactus is actually a member of Cactaceae, the cactus family. This is worth noting only because common names can be misleading. For example, the water lily is not a lily. But it is not a desert plant, which to some extent accounts for its more delicate appearance. Like most cacti, it has no leaves, but instead relies on its green stems for photosynthesis. The stems are flattened into vaguely leaf-like segments joined together like links. The flowers emerge from the joints or the ends of the stems.
The genus Schlumbergera is native to the coastal hills of southern Brazil where it lives in the forest either epiphytically (growing on other plants, as many tropical orchids do) or on exposed bedrock. Both of these habitats are relatively more subject to drying out than other places in a tropical forest, which accounts for this house plants tolerance for neglect.
There are six wild species, but two of them were hybridized in the 19th century to produce the first of a series of cultivars that are widely sold today. A decline in popularity in the early 20th century led some of the 19th century cultivars to be lost.
S. truncata gives rise to a group of hybrids that have zygomorphic flowers (bilaterally symmetrical) that are borne above the stems and have yellow pollen. The flattened stems have distinct points on their distal ends.
S. russelliana hybrids are referred to as the S. Buckleyi group (after the horticulturist who made the first crosses); the flowers of this group are actinomorphic (radially symmetrical) and hang below the stems. The stem segments lack the spines found in the truncata group.
The S. truncata group cultivars generally flower earlier in the fall and are therefore often referred to as “Thanksgiving cactuses.” The S. Buckleyi group tends to flower in December and January and so is more often called a “Christmas cactus.”
In their native Southern Hemisphere they all flower in May. The reversal of the timing in the Northern Hemisphere is due to its being induced by the seasonal shortening of days and lengthening of nights. It is the manipulation of this sensitivity that is the key to getting your house plant to live up to its common name.
My Christmas cactus spent last winter in the basement and didn’t flower at all. In fact, by the time I cleared the cobwebs off of it in May most of it was dead and even the weeds that had sprung up in it during its sojourn outside the previous year had dried up. I gently pulled off the withered stems of the cactus until it was mostly a woody stump with a few green segments remaining and put it outside.
It lived on the back deck between May and October getting full sun only very briefly (probably less than two hours) for part of the summer. It generally received only strong indirect light, which turns out to be exactly what this forest plant prefers. It recovered remarkably, with each bole of its woody stump sending a a few new stems that grew six to eight inches in a season.
I brought it inside in October before the first hard frost and put it in a cool nook that received indirect light most of the day (it faces northeast). It wasn’t particularly dark at night however, because the street lights shown into the room, but there was no overhead indoor light to turn on. In order to induce flowering horticulturalists recommend that a cactus be kept in absolute darkness for 12 to 14 hours for at least eight days in a row sometime in the fall.
It is also recommended that the plant we kept in a relatively small pot in a mixture of potting soil and either sand or vermiculite so that it never stays soaked for very long. Some sources recommend letting the plant dry out a bit in order to induce flowering, but other seemingly more scientific references suggest that there is nothing to this.
At any rate, my Christmas cactus, which is one of the S. Buckleyi cultivars is sending out several pink flowers right now. That is, it isn’t covered with blooms, but only gamely going through the motions, which given the only incidental “care” it’s received is about what can be expected.
*More recently I have been told that it is a cutting from a very old plant owned by our next door neighbor H. Mortimer Brockway and therefore dates from the 1970s.