Is it really a Christmas cactus?
Most plants sold as Christmas cactus are actually Thanksgiving cactus, or hybrids somewhere between the two. Care is much the same, but they bloom at different times. Three things to check:
- Stem segments. Christmas cactus has smooth, rounded scallops along each edge. Thanksgiving cactus has 2–4 pointed teeth that point upward. Easter cactus segments are smoother still, with faint ripples and a few brownish bristles at the tips.
- Flowers. Christmas cactus flowers hang down from the stem tips, and the pollen-bearing anthers in the middle are purplish-brown. Thanksgiving cactus holds its flowers out level or angled up, with yellow anthers. Easter cactus has flat, star-shaped flowers.
- Timing. Christmas cactus flowers from about December into February. Thanksgiving cactus starts about a month earlier, and Easter cactus waits for spring.
If yours has a bit of each, it’s probably a hybrid. Plenty of modern plants are.
Getting it to bloom again
Christmas cactus sets buds in response to long nights and cool temperatures, so the work starts in mid-September.
- Long nights. Give it bright light by day and about 14 hours of unbroken darkness each night. An unused room works, or cover it with a dark cloth from early evening to morning. Even a couple of hours of lamplight can stop buds forming.
- Cool nights. Aim for 55–65°F (13–18°C) at night. Above about 70°F (21°C), it may not bloom at all.
- Six to eight weeks. Keep this up, and buds usually show within three to four weeks. Once they appear, the darkness no longer matters.
- Then leave it alone. Keep the soil evenly moist and don’t move the plant until the first flowers open.
No dark room? Nights of about 55°F (13°C) in fall will often set buds whatever the day length. Don’t let it get colder than about 50°F (10°C), though, or the buds may drop.
Light
Bright, indirect light suits it best. Strong summer sun bleaches the segments pale or yellowish, but full sun in fall and winter does no harm. From September, keep it out of rooms where lamps stay on late, because light at night stops it setting buds.
Water
This is a rainforest cactus, so don't treat it like a desert one. Water when the surface of the soil feels dry, and never let the pot stand in water. Keep it evenly moist while it's in bud and flower, then water less after flowering until new growth starts.
Soil & pots
Use a light, airy potting mix that drains freely. Ordinary potting soil with about a quarter perlite mixed in works well. It flowers best slightly pot-bound, so repot only every three years or so, in spring.
Temperature
It grows best at 70–80°F (21–27°C) from spring to late summer, and can spend summer outdoors in part shade. Cool fall nights help it set buds. Once buds form, keep it away from heat vents, drafts and anything over 90°F (32°C), and bring it in before nights drop below 50°F (10°C).
Is Christmas cactus safe for pets?
Non-toxic to cats and dogs. The ASPCA lists Christmas cactus (under the older name Schlumbergera bridgesii) as non-toxic to dogs, cats and horses. It also notes that eating any plant can cause vomiting or an upset stomach, so discourage chewing.
Propagation
Christmas cactus roots easily from a short piece of stem. Take cuttings in late spring or early summer, after it has finished flowering and started growing again.
- Twist or cut off a piece 2–5 segments long, at a joint.
- Leave it overnight so the cut end can dry and callus.
- Push it about 1 in (2.5 cm) deep into moist perlite, sand or well-drained mix, the right way up.
- Keep it in bright, indirect light and water when the mix starts to dry. Roots take three to eight weeks.
Common problems
FAQ
Is Christmas cactus poisonous to cats?
No. The ASPCA lists Christmas cactus as non-toxic to cats, dogs and horses. As with any plant, a cat that eats a lot of it may vomit, so it's still best to discourage chewing.
How do I tell a Christmas cactus from a Thanksgiving cactus?
Look at the edges of the stem segments. Christmas cactus has smooth, rounded scallops; Thanksgiving cactus has 2–4 pointed teeth. Most plants sold as Christmas cactus are actually Thanksgiving cactus or hybrids.
Why won't my Christmas cactus bloom?
It's usually getting light at night, or it's too warm. From mid-September, give it about 14 hours of unbroken darkness and nights of 55–65°F (13–18°C) for six to eight weeks.
Why is my Christmas cactus dropping its buds?
Something changed while the buds were forming. A move, a draft, a warm spell, or soil that dried out or stayed soggy can all do it. Keep conditions steady and the soil evenly moist until it flowers.
When does a Christmas cactus bloom?
A true Christmas cactus flowers from about December into February. If yours reliably blooms in November, it's probably a Thanksgiving cactus.
Sources
- 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
- Schlumbergera truncata (Haw.) Moran: 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 x buckleyi: North Carolina Extension Gardener Plant Toolbox
- Schlumbergera × buckleyi: 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: University of Minnesota Extension
- Holiday Cacti Care: Penn State Extension