Sauk County Gardener: Thanksgiving or Christmas cactus – which is it?
“Life is tough, my darling, but so are you.” — Stephanie Bennett-Henry
As I was watering my houseplants, I noticed my Thanksgiving cactus had started blooming. Yes, I said Thanksgiving cactus, not Christmas. A couple years ago I was gifted with a Christmas cactus that was actually a Thanksgiving cactus. It was one of those inexpensive ones that are available at a variety of retail stores around Thanksgiving time. It was covered in buds, all ready for the holiday season, and I just assumed it was a Christmas cactus. In fact, I had never heard of Thanksgiving cactus. I didn’t figure it out until I researched why my cactus always seemed to bloom much earlier than Christmas.
For starters, there are three kinds of holiday cactus – Thanksgiving, Christmas and Easter, all native to Brazil. You can tell the difference primarily by looking at leaves (or segments), the time of year they tend to bloom, and the color of their anthers. The easiest way is to look at the leaf segments. The Thanksgiving cactus (Schlumbergera truncata) has claw-like segments with pointy “teeth” on the side of each segment. The Christmas cactus (Schlumbergera bridgesii) has more rounded, scalloped or teardrop-shaped leaf margins on the segments. The pollen bearing anthers on Thanksgiving cactus are yellow; the Christmas cactus are pink to purplish-brown. The Easter cactus (Rhipsalidopsis gaertnerrii) blooms in the spring, has very rounded edges and has a more-star shaped flower (it also needs eight to 12 weeks of short days to bloom).
These cacti prefer humid conditions but do not like to be overwatered. The soil should be dry to the touch before watering and not fertilized or repotted while blooming. As our houses tend to be dry, you can provide humidity by placing the plant on a small drip container filled with small rocks and water no higher than the rocks. They also like to be rootbound. If the plant turns reddish brown, it’s an indication of too much sun, lack of water, or lack of phosphorus. Mine tends to have reddish brown segments at times as I typically keep my plants in the same east-facing windowsill location all year long.
Whether you have a Thanksgiving or Christmas cactus, you can get blooms when you want them with a little bit of preparation. To get your Thanksgiving cactus to bloom in time for Thanksgiving, you needed to start mid-to-late September. But you have time to get it to bloom for Christmas. For both, temperature and day length are crucial bloom triggers. Both need about six to eight weeks of short days to bloom so the first week of November is a good time to start. (A short day is 12 to 14 hours of total darkness.) If the evening temperatures in your house are 55-70 degrees, it needs about 13 hours of uninterrupted darkness, 15 hours if the temperatures are greater than 70 degrees. Uninterrupted darkness means NO light so place the cactus in a closet, carefully covered by a dark cloth or in a dark basement. However, you must remember to bring it out each day so it gets light as well. If you use this method, put it to bed at 6 p.m. and bring it out between 6 and 8 a.m. If you are fortunate to have a window location that is a little cooler that is not drafty, you can simulate those same conditions at this time of year and not have to move the plant around. (Too much moving can cause the blooms to drop.) Once the buds appear, you can bring the plant into a brighter, warmer area in your house to enjoy where it should bloom for four to six weeks. After it’s done blooming, you can prune it back and resume normal watering and fertilizing when new growth appears.
No matter which kind of cactus you have, they are relatively easy to grow and share with others. Simply take a cutting of about four to five segments, let it “heal” over a few days, and then plant it in some barely moist potting soil about an inch deep. Place a plastic bag over it (but vent it frequently, so it doesn’t get too moist) in indirect light. You should see growth in about a month.
I tend to just let my Thanksgiving cactus bloom when it wants to, but if you want to add a little extra color or learn a new gardening technique, try making your Thanksgiving or Christmas cactus bloom in time for the holidays. The flowers are beautiful and a welcomed sight during the winter.
Remember to contact the University of Wisconsin Madison Division of Extension Sauk County staff if you have any gardening questions. Please send an email to haley.weisert@saukcountywi.gov or call the University of Wisconsin Madison Division of Extension Sauk County office at 608-355-3250.
Jeannie Manis is president of the Sauk County Master Gardeners Association (SCMGA).
