Thanksgiving or Christmas Cactus?
Both of these plants tend to be labelled as Christmas cactus, but there is a difference. The true Christmas cactus, Schlumbergera bridgesii, is very long-lived and is often passed down from one generation to the next.
The Thanksgiving cactus, Schlumbergera truncata, is the one you are most likely to find at the store. The bloom seasons overlap, so it can be difficult to know which one you have.
Both are true cacti, but they do not grow in the desert. They grow as epiphytes among tree branches in shady rain forests.
You can tell them apart by looking at their flattened stem sections. They do not have true leaves. The Thanksgiving cactus has pointy projections on the margins of the segments, while the Christmas cactus has more rounded projections.
The Christmas cactus has more tubular flowers primarily in pink, while the Thanksgiving cactus flowers are more flattened on the underside, and come in a variety of shades from red to pink to white.
Fortunately they both require the same treatment to encourage them to bloom: long dark nights and cool temperatures. In our area, providing long enough dark nights is easy, as our days get shorter and nights get longer just at the right time for these plants. It only requires that they are placed in a room where the lights are not kept on in the evening.
During the day they require bright light; an east-
or west-facing window is best. Most guides warn against placing them in direct sunlight, but with our sun low in the sky, some morning or evening sun is fine in fall, winter and spring – just not during summer.
Providing the proper temperature can be more difficult. Around this time we start heating our homes at temperatures comfortable for us. This is too warm to encourage our Thanksgiving or Christmas cactus to bloom.
If you like a cool bedroom, that might be the best place for your plant; 62 to 68 degrees F is ideal. The Christmas cactus is fussier than the Thanksgiving cactus, requiring more careful light and temperature control.
When you are encouraging flower buds to form, cut back on watering, but increase water once buds begin to grow. Keep moist until flowering stops, then treat the cactus the same as your other houseplants. The potting medium should be well-drained, but frequent repotting is not necessary. The Christmas cactus actually blooms better if it is slightly potbound.
Now is the time to provide your plant with the right conditions to get it to bloom. Your effort will be rewarded with a spectacular display while the garden sleeps under the snow.
Horticulturalist Mary Wright has lived in Denare Beach for over 20 years. She shares her passion for gardening with Flin Flon readers every second Wednesday in The Reminder.
