A Christmas cactus will rebloom every year if, in autumn, you give it what it gets in the wild: long, cool nights. In practice, from mid-September, keep it in a room with good daylight but no lamps on in the evening, where night temperatures fall to about 12–15 °C (55–60 °F), and water less often. Buds appear within a few weeks. From then on, leave the plant where it is and water it regularly until flowering ends. Most failures come down to a room that is too warm, a light that stays on every evening, or a sudden move once the buds have formed.
This guide explains what triggers flowering, sets out a care calendar for the whole year and covers the most common reasons for failure. For the botany of the genus, its species and its habitat, see our page on the genus Schlumbergera.
Christmas, Thanksgiving or Easter cactus: which one do you have?
Garden centres sell several closely related plants as “Christmas cactus”. They flower at different times and do not respond to quite the same cues, so it is worth identifying yours.
- Schlumbergera truncata and its cultivars, known as Thanksgiving cactus or crab cactus. Each stem segment has two to four pointed teeth along its edges, like a crab’s claws. The flowers are held roughly horizontally and have yellow anthers. This is the type most widely sold today, and it usually starts flowering in November.
- Schlumbergera × buckleyi, the “original” Christmas cactus, a hybrid between S. truncata and S. russelliana raised in England in the 19th century. Its segments have rounded, scalloped edges with no sharp teeth. The flowers hang down more and have purplish-brown anthers. It flowers a little later, around Christmas.
- The Easter cactus, Rhipsalidopsis gaertneri, long sold as Hatiora gaertneri or Schlumbergera gaertneri. Its segments are rounded with no teeth, and its flat, star-shaped, symmetrical flowers appear in spring. It needs different treatment, described below.
Christmas and Thanksgiving cacti are grown in exactly the same way; only the flowering date differs by a few weeks. In the rest of this article, “Christmas cactus” covers both.
Why flowering depends on the nights
Schlumbergera are epiphytic cacti from the mountain forests of south-eastern Brazil, where they grow on tree branches and mossy rocks. They are not desert plants: they live in partial shade and humid air, and their flowering is controlled by two seasonal signals.
Night length. These are short-day plants: flower buds only form when the plant gets at least 12 hours of uninterrupted darkness each night. Indoors, a lamp switched on in the evening in the same room is enough to “lengthen the day” and stop bud formation.
Cool nights. Temperature works together with night length and can even replace it. According to University of Minnesota Extension, at night temperatures of about 13 °C (55 °F), plants bloom in five to six weeks, sometimes regardless of day length. At 16–18 °C (60–65 °F), they need at least 12 hours of complete darkness each night for about six weeks. Above 18 °C (65 °F) at night, flowering is unlikely. That is why a Christmas cactus in a heated living room with the lights on until midnight often stays green, while the same plant in a cool spare bedroom flowers with no special effort.
One more point matters: flowers only form at the tips of the stems. A plant that has produced plenty of new segments over the summer has more places to flower.
The year-round calendar
The timings below apply to the Northern Hemisphere and largely follow the Royal Horticultural Society (RHS). In the Southern Hemisphere, shift everything by six months: the plants flower there in late autumn, around May.
End of flowering to late March: the post-flowering rest
Once the last flowers have faded, usually in late January, move the plant somewhere cooler, at about 12–15 °C (55–59 °F) and always above 10 °C (50 °F). Water less: let the top few centimetres (about an inch) of compost dry out between waterings, but never let the root ball dry out completely. Do not feed.
Late March to April: light pruning and repotting
This is the time to repot if needed, into a pot only slightly larger, using a light, free-draining mix (cactus compost, or potting compost opened up with perlite). A Christmas cactus flowers best when a little pot-bound, so repot only every two or three years, when the roots fill the pot. Remove a few segments from the stem tips to encourage branching; they make excellent cuttings (see our guide on how to propagate succulents).
April to mid-September: the growing season
Water regularly, keeping the compost moist but never waterlogged, and give a liquid houseplant fertiliser at half strength about once a month. Once there is no risk of frost, the plant can spend the summer outdoors in light shade, under a tree or against an east-facing wall, out of the midday sun, which turns the segments red and scorches them. Watch out for slugs and snails.
Mid-September until buds appear: bud initiation
This is the critical period. Stop feeding, water less (let the top of the compost dry out) and move the plant to a cool room at 12–15 °C (55–59 °F) with daylight but no lamps in the evening: a spare bedroom, an unheated but frost-free porch or conservatory, a stairwell. If the plant spent the summer outside, it can stay there while nights remain comfortably above 10 °C (50 °F); bring it in before the first cold snap. If you have no cool room, cover it each evening with an opaque box or put it in a cupboard from about 6 pm to 8 am for four to six weeks.
From the first buds to the end of flowering
As soon as buds are visible, go back to regular watering. The RHS then recommends returning the plant to about 18–20 °C (65–68 °F). In practice, if you need to move it, do so as soon as the very first buds show, then leave it alone: changes of position, light and temperature are the most common cause of bud drop. Turn the pot as little as possible.
Light, temperature, watering and feeding
Light. Bright but filtered. An east-facing window is often ideal; behind a south-facing window, screen the plant from direct sun with a sheer curtain. Too little light gives thin stems and few buds; too much gives reddish, scorched segments.
Temperature. 18–20 °C (65–68 °F) during growth and flowering, 12–15 °C (55–59 °F) during the two rest periods, and never below 10 °C (50 °F). Christmas cactus does not tolerate frost and cannot stay outdoors in winter except in frost-free climates.
Watering. This is a forest cactus: it dislikes prolonged drought as much as excess water. Water when the top of the compost is dry, empty the saucer after fifteen minutes and avoid decorative outer pots where water collects. Soft, wrinkled segments in summer mean the plant is too dry; segments that go soft at the base, a stem blackening at soil level and compost that stays wet point instead to root rot.
Feeding. Only during the growing season, at half strength. University of Minnesota Extension recommends a balanced fertiliser once a month from June to August; the RHS suggests a liquid feed from April to the end of September. Either way, give no nitrogen-rich feed during bud initiation or while the buds are developing.
Why the buds drop
Buds falling before they open is the most common complaint, especially with plants bought in flower. The recognised causes are:
- moving the plant after buds have formed, especially to a cooler or darker room, or constantly turning the pot;
- sudden temperature swings: cold draughts, a nearby radiator, very warm days followed by cold nights;
- a chill on the way home from the shop, common with December purchases;
- overwatering, or letting the compost dry out completely during flowering;
- very dry air and lack of light;
- more buds than a small or weak plant can support, so it sheds some of them.
A plant that drops its buds is not lost: leave it where it is, correct the cause and wait for the next cycle.
The Easter cactus
The Easter cactus (Rhipsalidopsis gaertneri) flowers in spring, between March and May in the Northern Hemisphere. It needs a cooler, longer winter than the Christmas cactus: the New York Botanical Garden recommends winter temperatures of 7–13 °C (45–55 °F), letting the compost dry out and giving only enough water to stop the stems shrivelling. University of Minnesota Extension notes that it takes eight to twelve weeks to set buds. After flowering, move it somewhere warm and resume watering. It is the most demanding of the three, and a plant kept in a heated home all year rarely flowers.
Common mistakes
- Treating it like a desert cactus: full sun and long dry spells wear it out.
- Leaving it all autumn in a heated room with the lights on in the evening: the number one reason it fails to flower.
- Feeding into the autumn, which keeps the stems growing at the expense of buds.
- Repotting into a pot that is too large, or repotting in autumn.
- Moving a plant in bud to show it off.
- Watering by the calendar instead of checking the compost.
Summary table
| Period (Northern Hemisphere) | Temperature | Watering | Feeding | Key task |
|---|---|---|---|---|
| Late January to late March | 12–15 °C (55–59 °F) | Reduced | None | Post-flowering rest |
| Late March to April | 18–20 °C (65–68 °F) | Gradually increased | None after repotting | Repot if needed, pinch stem tips |
| April to mid-September | 18–20 °C or outdoors in light shade | Regular | Half strength, about monthly | Growth, shade from direct sun |
| Mid-September until buds appear | 12–15 °C (55–59 °F) at night | Reduced | None | Nights of at least 12 hours with no artificial light |
| Buds and flowering | 18–20 °C, steady | Regular | None | Do not move the plant |
Frequently asked questions
Why is my Christmas cactus not blooming?
Most often because its autumn nights are too warm or too bright. Other causes are too little daylight, feeding too late in the season, a pot that is too large or a plant that is too young. From mid-September, give it cool, dark nights for at least six weeks.
Does a Christmas cactus really need to be kept in the dark?
Not in total darkness during the day: it needs daylight. What it needs is a night of at least 12 hours with no artificial light. If the room is cool, around 13 °C (55 °F) at night, this matters much less.
How long after short days begin will buds appear?
Christmas and Thanksgiving cacti bloom about six weeks after short days begin. The Easter cactus takes eight to twelve weeks.
My Christmas cactus blooms in November. Is that normal?
Yes. Most plants sold as Christmas cactus are cultivars of Schlumbergera truncata, the Thanksgiving cactus, which naturally flowers from November. Check the segments: pointed teeth along the edges confirm it.
Can I put my Christmas cactus outside in summer?
Yes, from late spring to early autumn, in partial shade and out of the midday sun. Bring it in before nights drop below 10 °C (50 °F), checking it for slugs and mealybugs first.
How long does a Christmas cactus live?
A very long time: the RHS describes it as a very long-lived plant. The more stems it develops over the years, the more flowers it carries, since every stem tip is a potential flowering site.
For more on forest cacti, see our pages on the genus Rhipsalis and the cactus family, Cactaceae, and our selection of the best indoor succulents.
Sources
- Royal Horticultural Society. How to grow Christmas cactus. rhs.org.uk/plants/christmas-cactus/growing-guide
- University of Minnesota Extension. Holiday cacti. extension.umn.edu/house-plants/holiday-cacti
- Penn State Extension. Holiday Cacti Care. extension.psu.edu/holiday-cacti-care
- New York Botanical Garden, Mertz Library. How can I care for my Easter cactus? libanswers.nybg.org/faq/223111
- Schlumbergera × buckleyi, history of the hybrid. schlumbergera.net/buckleyi