Christmas Cactus Care and How to Make It Rebloom

A Christmas cactus is an epiphyte, not a desert cactus, so it wants bright indirect light and soil that stays moist rather than bone dry. NC State Extension describes Schlumbergera x buckleyi as needing bright indirect light, with soil moist but not overly wet nor overly dry from spring to summer, in a well-drained airy medium of peat moss, sand and perlite. Full sun bleaches the stems.

Clemson Extension gives the growing temperature as 70 to 80 F in spring and summer, and says to water when the soil is dry to the touch, keeping it evenly moist once buds have set in autumn to prevent bud drop.

The flowering is the whole point, and it depends on light and temperature in September rather than on anything you do in December. That is covered in the next two sections.

NC State lists the plant as non-toxic for cats, dogs and children.

Bud set is triggered by long nights and cool nights, and the numbers are specific. Clemson's version: fourteen hours or more of continuous darkness each day, starting in mid-September and continuing for at least six continuous weeks, with as little as two hours of interrupted lighting enough to inhibit flower bud set; visible buds appear in three to four weeks. NC State gives the same trigger as at least thirteen hours of uninterrupted darkness every night from mid-September, with night temperatures of 55 to 65 F.

Temperature can substitute for darkness. University of Minnesota Extension says cool nights of 55 to 65 F can trigger blooming regardless of day length, and that plants will not bloom if night temperatures stay above 65 F. Clemson's bud-set range is 60 to 68 F, ideally close to 68 F.

A spare bedroom that is cool and genuinely dark at night does the job; a lamp switched on at ten o'clock undoes six weeks of it.

Bud drop is the other half of the flowering problem, and it has a short list of causes. NC State names sudden temperature changes, drafts, low humidity and improper watering. Clemson names temperature changes, light interruption and drying out. Minnesota's list is temperature fluctuations, drafts, humidity changes, shifts in light direction and moving the plant once budding has begun.

Once buds appear, stop rearranging. Do not move the pot to a different room, do not turn it to even up the growth, and do not let it dry out - Clemson says to keep it evenly moist after bud set.

Clemson also warns against temperatures below 50 F or above 90 F once buds have set, and Minnesota notes that below 50 F buds may drop.

Most plants sold as Christmas cactus are Thanksgiving cactus, and the difference is visible on the stem segments. Clemson gives the test: Thanksgiving cactus has two to four saw-toothed serrations or projections along the segment margins, while Christmas cactus margins are more rounded. Illinois Extension describes the Thanksgiving cactus teeth as looking like hooks or claws, against smooth, rounded or scalloped margins on Christmas cactus.

The flowers give a second check. Clemson notes Thanksgiving cactus has yellow anthers and Christmas cactus purplish-brown ones, and that Thanksgiving cactus flowers about a month earlier.

Illinois adds a third member, Easter cactus, with rounded margins but star-shaped flowers, blooming March to May.

Care is close enough that it rarely matters, but a plant that blooms in November is doing exactly what it should.

Clemson says to water when the soil is dry to the touch, to keep it evenly moist after bud set in autumn, and never to leave standing water in the saucer. NC State frames it seasonally: moist but not overly wet nor overly dry from spring to summer, with watering reduced from mid-September during bud development and again after flowering.

For soil, Clemson's figure is 60 to 80 percent potting soil with 40 to 20 percent perlite, well drained with good aeration. NC State describes an airy medium of peat moss, sand and perlite at an acidic to neutral pH. Minnesota recommends potting soil with peat moss and sand or perlite, and names root rot from overwatering as the leading cause of death.

Repot about once every three years, in spring, per Clemson - the plant flowers best somewhat pot-bound. Minnesota agrees, giving the same three-year interval.

Clemson feeds monthly during the growing season with a half-strength 20-10-20 or 20-20-20, adds an Epsom salt application of one teaspoon per gallon of water monthly, and stops in late summer for better autumn flowering. Minnesota's schedule is monthly from June through August with a balanced houseplant fertiliser at half strength, switching to a low-nitrogen, high-phosphorus formula such as 0-15-10 when buds form in autumn.

Propagation is easy and the timing is specific. Clemson says to take cuttings in May or June with three to five segments, rooting in three to eight weeks under a plastic cover, using three cuttings per four-inch pot or five per six-inch pot. Minnesota says to take cuttings after flowering where two branch sections join, dip in rooting hormone, keep the medium moist at 70 to 80 F, and expect roots within about two weeks.

Water from the top and let it drain; none of the sources we checked calls for bottom-watering. University of Minnesota Extension's method is to stand the plant in a sink to drain when watering and to empty saucers and decorative pots afterwards. What matters is that no water is left standing, because Minnesota names root rot from overly wet soil as one of the most common causes of death in these plants.

How often depends on the season:

• Spring and summer. The RHS says to water regularly from April to September, keeping the compost moist but never waterlogged. Planet Desert's guide gives every 7 to 10 days as a typical interval, when the top inch feels dry.
• Autumn rest. The RHS reduces watering from mid-September until buds appear, letting the top few centimetres dry between waterings. Once buds have formed, Clemson Extension says to keep the soil evenly moist to prevent bud drop.
• After flowering. Minnesota says to water less often after blooming and increase again in spring or early summer; the RHS gives a second rest from late January to March.

There is no evidence in the sources we checked that they do anything special for it. University of Minnesota Extension says coffee grounds feed soil organisms and are an excellent compost ingredient, but have not been shown to consistently lower soil pH - the usual reason people give for adding them.

The practical concern is water. A Christmas cactus that dies usually dies of root rot, and a layer of damp grounds on the surface keeps the mix wet longer. Compost the grounds, and feed the plant with a houseplant fertiliser on the schedule in the feeding section above.

The same Minnesota page is cautious about Epsom salts, which some growers - including Clemson Extension's holiday cactus sheet - add monthly: Minnesota says there is no need unless the soil is short of magnesium, and that too much magnesium can block calcium uptake. If you use it, keep to Clemson's rate of one teaspoon per gallon.

Many decades. University of Minnesota Extension says holiday cacti can be very long-lived, can live over 100 years, and are often passed down from generation to generation. The garden supplier Beat Your Neighbor features a family plant it estimates at about 125 years old.

The old plants that survive are the ones that were never kept wet. Minnesota's warning is the one to remember: root rot from overly wet soil is among the most common causes of death.

• Keeping it wet. Root rot is the main killer (Minnesota Extension); Planet Desert also lists overwatering first.
• Full sun. The RHS says bright light but not full sun, ideally an east-facing windowsill.
• Lights on at night in autumn. The RHS lists artificial lighting interference as a reason for no flowers, and Clemson says as little as two hours of interrupted lighting can stop bud set.
• A warm room in autumn. The RHS wants a cool spell of 12 to 15 C (55 to 59 F) from mid-September to trigger flowering.
• Moving it once buds form. Temperature swings and cold shop conditions cause bud drop (RHS), and a heating vent or draught does the same (Planet Desert).
• Feeding through the flowering period. Planet Desert lists it as a mistake; the RHS feeds from April to the end of September only.
• A pot that is too big. The RHS says to choose a pot only slightly larger, and lists overpotting as a cause of poor growth.

Note that care guides disagree on the darkness figure: Planet Desert gives 8 to 10 hours of darkness at night, while Clemson and NC State Extension give 13 to 14 or more hours of unbroken darkness. We follow the extension figures in the reblooming section above.

The sections on watering method and frequency, coffee grounds, lifespan and common mistakes were added on 2026-09-25. Research and drafting were done with the help of AI, and every figure was checked line by line against the sources listed on this page.

Use a balanced houseplant fertilizer at half strength once a month in the growing season, and stop before or during flowering. The sources agree on that much and differ on autumn:

• Spring and summer. The RHS applies a liquid houseplant feed from April to the end of September. University of Minnesota Extension feeds monthly from June through August with a balanced houseplant fertilizer at half strength. Clemson Extension, cited in the feeding section above, uses a half-strength 20-10-20 or 20-20-20 monthly.
• Autumn, when buds form. Minnesota switches to a fertilizer low in nitrogen and high in phosphorus and potassium, giving 0-15-10 as an example. Clemson instead stops feeding in late summer for better autumn flowering.
• While in flower. No feeding in any of the sources; Planet Desert lists feeding through flowering as a mistake (see the mistakes section).

Which autumn approach to follow matters less than the bloom triggers below. If you want one rule, feed monthly at half strength from spring to the end of summer, then stop.

The three numbers on a fertilizer label are nitrogen, phosphorus and potassium, in that order. A 0-15-10 feed has no nitrogen, which is why Minnesota uses it once leaf growth should stop and buds should take over.

What sets flower buds is autumn conditions, not feed. University of Minnesota Extension says holiday cacti need about six weeks of shorter days combined with cool nights of 55 to 65 F; at 55 F nights they bloom in about five to six weeks, sometimes regardless of day length; with nights of 60 to 65 F they need at least 12 hours of complete darkness every night for about six weeks; and they are unlikely to bloom if nights stay above 65 F. The RHS gives the same two reasons for no flowers: artificial light after dark, and temperatures that do not fall below 18 C (65 F) in autumn.

So the most useful things you can put on a Christmas cactus to help it bloom are a cool room and a dark night. Our reblooming section above gives the full schedule.

Long, uninterrupted nights and cool temperatures. Either one can set buds, and together they work best. The sources give slightly different figures, so here they are side by side:

• Chicago Botanic Garden: cool nights of 50 to 55 F, or 13 hours of unbroken darkness if it is 55 to 70 F, or 15 hours of darkness above 70 F. Start about eight weeks before you want flowers.
• University of Minnesota Extension: at least 12 hours of complete darkness every night for about six weeks, with days of 65 to 70 F and nights of 55 to 65 F; at 55 F nights, blooms in about 5 to 6 weeks, and above 65 F nights the plant is unlikely to bloom.
• University of Illinois Extension: at least 12 hours of continuous darkness for 5 to 6 weeks; interrupting the dark for 2 hours or more can stop bud formation, and temperatures below 50 F can make buds drop.
• Clemson HGIC: 14 hours or more of continuous darkness before buds set.

In practice: from late September, keep it in a cool room that nobody lights at night, or cover it or move it to a closet each evening, and keep the nights between about 50 and 65 F.

Chicago Botanic Garden says a Christmas cactus stays in flower for four to six weeks, with each flower lasting six to nine days. Clemson HGIC reports that plants kept at 68 F can bloom for up to 7 to 8 weeks. Cool conditions also affect colour: Wikipedia notes that temperatures below 14 C (57 F) give pink tones to white and yellow cultivars and deepen the colour of pink and red ones.

Once, as a rule. The extension and botanic garden sources we opened all describe a single main flowering season, triggered by the long nights and cool temperatures of autumn; Wikipedia notes that in Brazil, where the plants come from, they are called flor de maio, May flower, after their flowering time in the southern autumn. Clemson HGIC mentions that the related Easter cactus flowers mainly in spring and sporadically through the year.

None of the sources promises a second flush for Christmas or Thanksgiving cactus. Because buds form whenever the nights are long and cool enough, a plant that meets those conditions again can set a few more buds, but do not count on it.

A plant in flower is telling you it had the long, cool nights it needs, so your autumn routine worked. The timing tells you something too. The University of Illinois Extension says most plants sold as Christmas cactus are actually Thanksgiving cacti, and Clemson HGIC says Thanksgiving cacti flower about a month before Christmas cacti. If yours blooms in November, check the stem segments: Clemson describes 2 to 4 pointed, saw-tooth projections on each edge for Thanksgiving cactus and more rounded edges for Christmas cactus. Wikipedia adds two flower clues: Thanksgiving cactus holds its flowers roughly level and has yellow pollen, while Christmas cactus flowers hang down and have pink pollen.

• Do not move it. Chicago Botanic Garden names moving the pot around as a cause of bud drop, and the University of Minnesota adds that changes in the direction and amount of light can make buds fall.
• Avoid drafts and swings in temperature (University of Minnesota), keep it above 50 F (University of Illinois), and below 90 F once buds have set (Clemson HGIC).
• Water a little more often, not more at a time. Chicago Botanic Garden advises watering when the top inch is dry, increasing the frequency but not the volume once buds appear, and warns that overwatering after bud set also causes bud loss.

• Let it rest. The University of Minnesota says to water less often after flowering, then increase watering in spring or early summer when growth resumes; Illinois says to cut back slightly until new growth begins.
• Prune to shape. Cut or pinch back at the joints between segments; the University of Minnesota says each cut produces 1 to 2 new segments, which means more branch tips and more flowers next year. Chicago Botanic Garden suggests pinching off enough sections to give an even shape.
• Feed when it grows. Illinois advises fertilising from spring, once growth resumes, through late summer.
• Repot only when needed. Illinois repots every three years or so, in a mix of 60 to 80 percent potting soil with 40 to 20 percent perlite.

Then start the long-night routine again in autumn.