Thanksgiving or Christmas cactus?
Thanksgiving cactus is the holiday cactus you’re most likely to find in stores, and it’s often sold as Christmas cactus. Three ways to tell:
- Teeth. Each stem segment has 2–4 pointed, claw-like teeth along its edges, pointing upward. Christmas cactus segments have smooth, rounded scallops instead.
- Flowers. They stand out level or angled up from the stem tips, with yellow anthers (the pollen-bearing tips in the center). Christmas cactus flowers hang down, and their anthers are purplish-brown.
- Timing. Mid-November into December, about a month ahead of a true Christmas cactus. Easter cactus, the third holiday cactus, waits until spring and has flat, star-shaped flowers.
Flower color is no help: Thanksgiving cactus comes in white, pink, red, lavender, salmon-orange and shades in between. Some plants show a mix of traits, because many modern cultivars are hybrids.
Getting it to rebloom
Thanksgiving cactus is a short-day plant. It sets buds when nights are long and temperatures cool. A bright spare room where nobody switches on a light after dark is ideal.
- Start in mid-September. Give it bright light by day and 14 hours or more of unbroken darkness every night. As little as two hours of lamplight, car headlights or a streetlight can stop buds forming.
- Keep it on the cool side. Fall temperatures of 60–68°F (16–20°C) are ideal. Nights of 50–59°F (10–15°C) will set buds whatever the day length, though growth slows and buds may drop if it gets down to 50°F (10°C).
- Hold it for six weeks or more. Buds normally show in three to four weeks. After that, day length no longer matters.
- Stop feeding by late summer. Then keep the soil evenly moist once buds form, and don’t move the plant until they open.
Light
Give it light shade or bright, indirect light. It enjoys full sun in midwinter, but summer sun turns the segments pale and yellowish and can scorch them. In fall, keep it away from lamps that stay on after dark, or it won't set buds.
Water
Water when the surface of the soil is dry to the touch. It copes with going a little dry in spring and summer, but don't let the pot dry out completely or sit waterlogged, especially through the dark days of winter. Once buds form, keep it evenly moist.
Soil & pots
It needs a light, well-aerated mix and won't grow well in heavy, wet soil. Ordinary potting soil with about a quarter perlite mixed in works well. It flowers best a little pot-bound, so repot only every three years or so, in spring.
Temperature
Ideal growth is at 70–80°F (21–27°C) from April to September. Fall temperatures of 60–68°F (16–20°C) give the best flowering. Once buds are set, keep it below 90°F (32°C), since steady warmth makes them drop, and bring it in before nights fall below 50°F (10°C).
Is Thanksgiving cactus safe for pets?
Non-toxic to cats and dogs. The ASPCA doesn't list Thanksgiving cactus by name, but it lists the closely related Christmas cactus as non-toxic to dogs, cats and horses. NC State Extension lists Thanksgiving cactus itself as non-toxic to cats and dogs. Eating any plant can still cause vomiting or an upset stomach.
Propagation
Thanksgiving cactus is one of the easiest plants to root. Take cuttings in May or June, once it's growing again.
- Twist or cut off a piece 2–3 segments long, at a joint.
- Leave it a day or two for the cut end to callus.
- Set it upright, about 1 in (2.5 cm) deep, in moist, well-drained potting mix.
- Water when the mix is dry. Roots form in a few weeks.
Common problems
FAQ
Is a Thanksgiving cactus the same as a Christmas cactus?
No, but they're close relatives and constantly mixed up. Thanksgiving cactus has pointed teeth on its stem segments and blooms about a month earlier. Christmas cactus is a hybrid of Thanksgiving cactus and another Brazilian species.
Is Thanksgiving cactus safe for cats and dogs?
NC State Extension lists it as non-toxic to cats and dogs, and the ASPCA lists the closely related Christmas cactus as non-toxic. A pet that eats a lot of any plant may still vomit.
Why didn't my Thanksgiving cactus bloom?
Usually light at night or a room that's too warm. From mid-September, give it 14 hours or more of unbroken darkness every night for at least six weeks, and keep it cool.
Can a Thanksgiving cactus bloom twice a year?
Sometimes. After its main show in late November, it may bloom again as the days lengthen in February.
How long do the flowers last?
Flowering typically lasts about five weeks. Clemson Extension notes it can stretch to 7 or 8 weeks if the plant is kept at 68°F (20°C).
Sources
- Schlumbergera truncata (Haw.) Moran: Plants of the World Online, Royal Botanic Gardens, Kew
- Schlumbergera × buckleyi (T.Moore) Tjaden: Plants of the World Online, Royal Botanic Gardens, Kew
- Schlumbergera russelliana (Hook.) Britton & Rose: Plants of the World Online, Royal Botanic Gardens, Kew
- Christmas Cactus: ASPCA Toxic and Non-Toxic Plants
- Toxic and Non-Toxic Plants: ASPCA Animal Poison Control
- Schlumbergera truncata: North Carolina Extension Gardener Plant Toolbox
- Schlumbergera truncata: Missouri Botanical Garden Plant Finder
- Thanksgiving & Christmas Cacti (HGIC 1554): Clemson Cooperative Extension
- All About Holiday Cacti: Iowa State University Extension and Outreach
- How to identify and care for holiday cacti and get them to rebloom: University of Illinois Extension
- Holiday Cacti Care: Penn State Extension