The Thanksgiving cactus (Schlumbergera truncata) and Christmas cactus (Schlumbergera bridgesii) are popular winter-flowering houseplants native to South America and come in many colors: red, rose, purple, cream, white, peach and orange. The Schlumbergera species grow as epiphytes (non-parasitic plants that grow upon others) in the rain forests.
To distinguish the difference between a Thanksgiving and a Christmas cacti, look at the shape of the flattened stem segments called phylloclades. On the Thanksgiving cactus, these segments each have saw-toothed serrations or projections along the margins. The stem margins on the Christmas cactus are more rounded and less pronounced.
Since flowering plants sell better than nonflowering, merchants tend to fill their shelves with Thanksgiving cacti.
Light & Temperature: Full sunlight is needed during fall and winter, but bright sun during the summer months can make it look pale and yellow. Ideal spring and summer growth (April through September) occurs at temperatures between 70F to 80F. During the fall, the cacti depend upon shorter day lengths (8 to 10 hours) and cooler temperatures to set their flower buds. Do not allow temperatures to rise above 90F, once the flower buds are set. Temperature changes can cause flower buds to drop. Do not leave these cacti outside if temperatures will drop below 50F.
The secret of good flower bud production during the fall involves temperature regulation and photo period (length of day and night) control.
To initiate flower buds, the plants need:
- A bright location.
- Fourteen hours or more of continuous darkness each 24 hour period is required
before flower buds will occur. Long nights should be started about the middle of September and continued for at least 6 continuous weeks for complete bud set. Just like the poinsettia.
- Fall growing temperatures should be between 60F and 68F, but as close to 68F as possible for maximum flower production. Plants grown with night temperatures between 50F and 59F will set flower buds regardless of day length, but growth will be slower.
- Pinching at the end of September to remove any terminal phylloclades that are less than a half inch long, to make all stems approximately the same length. These short, immature stem segments will not make flower buds.
Growing Media: These cacti flower best when kept somewhat pot bound. The potting medium must be well-drained with good aeration, as these cacti do not grow well in heavy, wet potting mixes. A good mix may contain 60-80% potting soil with 40-20% perlite.
Watering & Fertilizer: The cacti are tolerant of dry, slightly under-watered conditions during the spring and summer. Following bud set in the fall, the growing medium should be kept evenly moist to prevent flower bud drop. Yet, never let the plant sit in water.
Fertilize plants monthly when new growth starts in late winter or early spring, and throughout the summer using an even (20-20-20) soluble fertilizer, with trace elements. These cacti have a higher requirement for magnesium. To satisfy this need, treat monthly during the growing season with Epsom salts (magnesium sulfate) mixed with 1 teaspoon per gallon of water, but do not apply the same week as the regular fertilizer. Stop fertilization during the late summer for better flower bud production in the fall.
Propagation: Holiday cacti are easy to propagate by cuttings, which should be taken in May or June.
- Pinch off single sections from stems with at least 3 to 5 stem segments.
- Allow the cut ends of the sections to callus by allowing them to layout on newspaper for about 48 hours.
- Disinfect containers and use a well-drained potting soil for rooting.
- Place 3 – 4 cuttings at approximately one inch deep into the potting soil of a 4-inch container, or more for larger pots.
- Water the soil well and cover container with a clear plastic bag secured with a rubber band. The plastic bag will act as a miniature greenhouse to keep the humidity high to enhance rooting.
- Place the container in bright, indirect light until roots have formed in about three to seven weeks.
- At this time the plastic bag can be removed, and a low fertilizer solution (10-10-10) can be used.
Issues in Flowering:
Both cacti commonly drop unopened flower buds, because of one of the following:
- Sudden change in temperature.
- Allowing the growing medium to dry out.
- Lack of flowering is often due to light interrupting the long night period (14 hours) that is required for flowering initiation to occur. Street lights, car lights or indoor lighting can disrupt the required dark period.
Disease & Pests:
- Root rot, which can be prevented by avoiding excessive watering or the plant sitting in water.
- Insects and related pests can include: mealybugs, soft brown scale, red spider mites, aphids and fungus gnats.
These are some of the easiest plants to car for! I have actually never done anything more than keep mine in a southern window year round, water and fertilize during the summer, kept it out of drafts yet humid and it blooms like crazy for about 60 days.
Thanks for visiting & keep on planting!
© Ilex Farrell ~ Midwestern Plant Girl