Christmas cactus collects questions almost as fast as it collects buds. Four come up again and again:
- Why won’t it bloom?
- It flowered last year, so why not this year?
- How often should I water it?
- Why is the base rotting?
The answers trace back to one fact: despite the name, this is a rainforest plant, not a desert cactus. It is a popular gift plant because of its colorful blooms and easy-care reputation, and once you get its moisture, its spot and its fall routine right, most of the drama goes away. Read on, or know more about Christmas cactus in our owner’s guide.
What You’re Actually Growing
The Christmas cactus most of us buy is Schlumbergera × buckleyi, a hybrid. William Buckley created it in England around 1850 by crossing two southeastern Brazilian species, and it is an epiphyte, a plant that grows on trees rather than in the ground. The Royal Horticultural Society adds that these plants come originally from tropical rainforests, where they grow in dappled light and warm, humid conditions. Some sources list it as Schlumbergera bridgesii, and botanists have yet to agree on the taxonomy, so you may see it under different names.
It also has two look-alikes. The Thanksgiving cactus (Schlumbergera truncata) has flattened stems with pointed teeth along the edges and tends to bloom around Thanksgiving. The Christmas cactus has scalloped, claw-like stem segments and typically blooms in December. The Easter cactus (Rhipsalidopsis gaertneri) has rounder, more segmented stems and usually blooms around Easter. The three share similar care requirements, so most of what follows applies to all of them.
Christmas Cactus Quick Care Tips
- Botanical Name: Schlumbergera × buckleyi, also listed as S. bridgesii
- Common Names: Christmas cactus, holiday cactus
- Family and Origin: Cactaceae; parent species from southeastern Brazil
- Growth Habit: Epiphyte, with pendant chains of flat stem segments
- Hardiness: USDA zones 10 to 12; frost-intolerant
- Size: About 1 to 2 feet tall and wide
- Flowers: Magenta red to pink, from about December to February
- Light: Bright, indirect light
- Humidity: Prefers humid air; the air in homes is often dry
- Temperature: About 60 to 70°F, or 70 to 80°F in the growing season; avoid sudden swings
- Soil: Light, well-drained and rich in organic matter
- Water: When the top inch of soil feels dry
- Fertilizer: Every month or two, April to September
- Pests and Problems: Mealybugs, scale, red spider mites and aphids; root rot in soggy soil; bud drop
- Propagation: Stem cuttings
- Pets: Non-toxic to dogs and cats, per the ASPCA
How To Get A Christmas Cactus To Bloom
Christmas cactus flowers on a seasonal schedule. Like poinsettias and chrysanthemums, it is a short-day plant. It grows in the long days of summer and forms flower buds in response to the shorter days of fall, and cooler temperatures also help. Blooming is mostly a matter of giving it the fall it wants.
Botanical gardens and extension services give slightly different recipes, and they all point the same way:
- The Chicago Botanic Garden says flower buds form if nights are 50 to 55°F, or with 13 hours of uninterrupted darkness when temperatures are between 55 and 70°F, or with 15 hours of darkness above 70°F.
- The Missouri Botanical Garden suggests, from mid-September for Christmas bloom, bright days, 55 to 65°F nights and 13 hours of total darkness for 6 to 8 weeks. It adds that if nights can be kept at 45 to 55°F, buds usually form without the strict darkness routine.
- UF/IFAS says Christmas cactus typically needs at least twelve hours of darkness. Its extension article puts plants in a dark closet from 5 p.m. to 8 a.m. for six weeks, with blooms about ten weeks after starting, so a start on October 14 would give full bloom around December 23.
Dark has to mean dark. Uninterrupted darkness means no light during the dark period, including lamp light in the home, so cover the plant with a black cloth or plastic bag or put it in a closet. Plants exposed to any artificial light, like a streetlight, will not set flower buds as expected. To find your start date, count back eight weeks from the date you want flowers.
Water a little differently during this stretch. Reduce watering from mid-September until buds start to develop with the shortening days, letting the top few centimeters of the mix dry out between waterings but never letting it dry out entirely. Don’t fertilize or overwater. Once you see flower buds, resume watering until the flowers fade.
Once buds show, keep the plant steady. Too much water can make buds fall, and so can moving the pot around. Drafts and heat sources such as vents, fireplaces and televisions can cause bud drop, and so can letting the plant get too dry between waterings. Temperatures above 90°F and large temperature swings are other causes.
When the show starts, the plant stays in flower for four to six weeks, with each flower lasting six to nine days. After flowering, pinch off enough sections to keep the plant uniform, then resume normal watering and feeding when new growth appears.
Watering: Moist, Not Soggy
Because it comes from the rainforest, Christmas cactus does not want desert-style neglect or a swamp. Water when the top inch of soil feels dry to the touch, soak the soil until water runs out the drainage holes, wait a few minutes, then discard whatever has collected in the drip pan. Water on that signal rather than on a fixed schedule.
Both extremes cost you. The stems and roots can rot if the soil holds too much water, and allowing the soil to dry out will cause flowers to drop. So the old advice that Christmas cactus thrives on neglect only goes so far: let it dry out and you risk losing flowers.
About that layer of pebbles or broken pot pieces some people put in the bottom of the pot: Washington State University Extension horticulturist Linda Chalker-Scott says drainage material added to containers only hinders water movement. Use good soil throughout the container instead, and make sure the pot has drainage holes.
Humidity matters too. Christmas cactus prefers humid conditions, and homes are often dry. Set the pot and its drip pan on a small container of pebbles, adding water to the pebbles without letting it rise above the bottom of the top layer, so evaporation raises the humidity around the plant.
Soil and Potting
Aim for a light, well-drained mix that is still rich in organic matter. A mix of two parts peat moss to one part perlite works, and peat moss with perlite, vermiculite or builder’s sand are all acceptable. Another recipe is one part potting soil, two parts peat moss and one part sharp sand or perlite. Either way, use a pot with open drainage holes, and see our guide to the best soil for Christmas cactus for more.
Christmas cactus prefers to be a bit root-bound, so don’t choose a pot that is too large; one only slightly larger is right. University of Missouri Extension says keeping it slightly pot-bound induces prolific flowering.
Light, Temperature and Summer Outdoors
Bright, indirect light is the target. Place it within six feet of a south, east or west window; any light exposure works except a north window. An east-facing windowsill is usually ideal, and these plants dislike full sun. Full sun in the growing season will bleach the foliage of container plants brought outdoors.
For temperature, a comfortable range is 60 to 70°F, without sudden fluctuations, though ideal growing-season temperatures are also put at 70 to 80°F. Either way, keep it away from drafts and from heat sources such as vents and fireplaces.
In summer it can go outside. Move it to a warm, sheltered, shady spot, keep it out of full sun, protect it from slugs and snails, and bring it back indoors at the end of summer before temperatures drop. Christmas cactus is frost-intolerant, but it can be grown outdoors in the warmer areas of Florida if it is protected from freezing temperatures. Outdoor plants often set buds on their own once mid-September nights fall into the 50 to 55°F range. For more, see Christmas cactus outdoors.
Feeding, Pruning and Repotting
The growing season runs April to September, and that is the window to start fertilizing Christmas cactus. Fertilize every month or two depending on growth, monthly if it is growing quickly; soluble or slow-release products both work. Use less than the label rate, because excess fertilizer salts can damage the roots. Reduce fertilizing during fall and winter.
Pruning pays off. It encourages branching and flowering but should not go beyond mid-summer: prune after bloom when new growth begins, with the last pruning in late spring. Here’s why it works: flowers form only at the stem tips, so more stems mean more flowers.
Repot only when the roots have filled the pot, and choose a pot only slightly larger. A newly bought plant can stay in its original pot for a couple of years, then needs repotting every year or two, in spring at the start of the growing season. Estimates vary, though; repotting may be needed only about every three years.
Propagating Christmas Cactus
Cuttings are the simpler route. Use trimmings with two or three jointed sections in a well-drained, sterile medium, keeping them moist in bright indirect light until roots form and new growth appears. Snap or cut off a couple of segments at a joint, leave the cutting a day or two to let the wound dry out, and push it in about half an inch deep, or just deep enough to keep it upright, because a cutting set too deep is more likely to rot. For the full walk-through, see how to propagate Christmas cactus. Grafting is another way to propagate it.
Christmas Cactus Questions and Answers
Question: I’ve had a Christmas cactus for years and have transplanted it, grown it in sun and in shade, kept it dry and damp with no luck. It grows well and looks healthy. How do I make a Christmas cactus bloom? M. K., Chicago, Ill.
Answer: M.K., your timing may be off, and the better question may be how often to water Christmas cactus. Water regularly from April to September, then ease back from mid-September until buds appear. If you keep your Christmas cactus outdoors in summer, in a shady spot, bring it in before temperatures drop. Then give it long, uninterrupted nights: about 13 hours of total darkness for six to eight weeks.
More on Caring For Christmas Cactus
- How To Repot A Christmas Cactus
- Why Do Christmas Cactus Turn Yellow?
- My Christmas Cactus Does Not Bloom – Why?
- Problems and Diseases Christmas Cactus Face
Frequently Asked Questions
Are Christmas cactus easy to care for?
Yes, once you treat it like the rainforest plant it is. It has an easy-care reputation, and the basics are bright indirect light, a well-drained mix and water when the top inch of soil feels dry. The one part that takes planning is bloom timing, which comes down to long, dark fall nights.
How do I get my Christmas cactus to bloom?
Give it long, uninterrupted nights in fall: about 12 to 13 hours of total darkness for six to eight weeks, with night temperatures of 55 to 65°F, and even lamp light breaks the dark. Count back about eight weeks from when you want flowers, and ease back on watering until buds appear.
How often should I water a Christmas cactus?
Water when the top inch of soil feels dry, not on a fixed schedule. Soak until water runs out the drainage holes, then empty the saucer. Don’t let the plant dry out completely, since that can drop flowers, and soggy soil can rot the stems and roots.
When should I repot a Christmas cactus?
Repot only when the roots have filled the pot, and choose a pot only slightly larger. Do it in spring, at the start of the growing season, every year or two after the first couple of years, though repotting may be needed only about every three years.
Is Christmas cactus safe for cats and dogs?
Christmas cactus, filed under the name Schlumbergera bridgesii, is listed as non-toxic to dogs, cats and horses. Some sources use that name for Christmas cactus and others use Schlumbergera × buckleyi, so match the name on your plant tag if you are checking a specific plant.