Let me start by saying I’ve killed my share of houseplants, but one that has lived for close to three decades is the Zygocactus. Commercially, growers sell two slightly different plants as Zygocactus: the Thanksgiving cactus which has pointy edged branch segments and blooms around turkey time and the Christmas cactus which has rounded segments and blooms for its namesake. Care for the plants is essentially the same. Mine, shown above, is the Thanksgiving variety, Schlumbergera truncate. Through periods of neglect, inconsistent feeding and infrequent (twice maybe?) repotting, this plant keeps blooming prolifically year after year. I’ve rooted cuttings several times as gifts, but curiously, its offspring have rarely flowered in their new homes, where I might add, they get more TLC than they would living with me. This begs the question, what does this plant need to thrive and re-bloom? Here are the best tips from the experts and a few of my own observations.
- It likes a bright, but not sunny location with temperatures that do not drop below 60 degrees. Mine moves from indoors to an east facing screened porch from Memorial Day till Labor Day, or longer if the fall is mild like it was this year.
- It is a cactus which likes humidity. Unlike most cactus which prefer dry air, it hails from the tropical rainforests of South America and likes moist air. Sitting the plant on a pebble tray with water that does not touch the bottom of the pot can help, or living in a kitchen or bathroom would be ideal.
- It wants good drainage. If repotting, use standard, well draining potting soil. Water when it is dry just below the soil line, about once a week. I’ve found it amazingly forgiving
ifwhen I forget to water. Over-watering will cause branches to rot, so more is not always better.
- Spring and Summer are its active growth times. Prune when it is done blooming or in early summer to promote side branching. Cuttings can easily be rooted in water or soil. Adding houseplant food during the growth period helps. I have cut back branches to about six inches in the spring and the plant tripled in size by the end of the summer.
- Here’s the key! It needs longer autumn nights to rebloom. Photoperiodism is a plant’s reaction to periods of light, similar to our circadian rhythm. Starting in mid to late September, the Zygocactus needs between nine and twelve hours of uninterrupted darkness each day in order to flower. Thanksgiving cactus take about six weeks of longer nights to sprout buds, Christmas cactus need about eight to twelve weeks. This longer “sleep” period is the trickiest part of the reblooming process and why the porch, which is generally dark at night, works so well. Other options are to locate the plant in a similarly lit room, or early each evening, cover it with a box or put it in a closet. Complete darkness insures maximum blooms. From experience, I’ve found that the occasional interruption of darkness reduces blooms, but will not thwart all flowers.
- Stop the longer night process when buds emerge. The plant is now ready to flower. At this time, reduce watering slightly to promote brighter flower color.
- Watch for bud drop. This could indicate you’ve reduced water too much. If the plant is new to you, it also could be reacting to a change in environment. Drafts or temperatures below 60 degrees may also be the culprit. I often see shriveled tiny buds at the end of the blooming cycle, as though the plant is exhausted from the work it takes to flower for weeks on end. I found no science to support this notion, just my take on it!
Zygocactus are graceful, pretty plants, with or without blooms. Their showy, colorful holiday flowers are a beautiful treat at the end of the year. With a little extra care in the fall, they will regale you with splendid holiday color.
By Linda McDonnell, a Denver County Master Gardener