Carlos Aguilar, Tecmanic
Christmas Cactus Care: How to Water, Light, and Get It to Bloom
A Christmas cactus wants bright, indirect light. While it is budding and flowering, keep the soil evenly moist; dryness can cause buds or flowers to drop. To set buds in fall, give it long, uninterrupted nights — at least 12 hours of darkness (Illinois, SDSU), or 14–16 hours for most cultivars (Iowa State) — and keep it cool, around 55–65°F at night. Iowa State says temperatures above 70°F prevent flowering.
The ranges below come from Illinois Extension, Iowa State Extension, SDSU Extension, and Clemson HGIC. When those pages use different numbers, each number stays with the page that printed it.
Christmas cactus care basics
Watering
Iowa State and Illinois do not describe the same dry-down once the plant is out of flower. Both are listed here.
| Source | While budding or flowering | After flowering, or when not in flower |
|---|---|---|
| Iowa State | Keep the soil evenly moist. Dryness can cause buds or flowers to drop. After flowering, move the plant to a cooler location and water less frequently. | Allow the soil to dry completely between waterings. Overwatering leads to limp growth and root rot. |
| Illinois | Keep the soil moist, and do not leave the plant sitting in water. If it gets too dry while blooming, it may drop its flowers. | Resume watering like normal, allowing the soil to dry out slightly between waterings. |
Iowa State’s lines are: “While the plant is budding and flowering, keep the soil evenly moist. Dryness can cause buds or flowers to drop. After flowering, move to a cooler location and water less frequently.” When the plant is not in flower: “Allow the soil to dry completely between waterings. Overwatering leads to limp growth and root rot.”
Illinois says: “Soil should be kept moist, but make sure they aren't sitting in water. If plants get too dry while blooming, plants may drop their flowers.” After flowering: “resume watering like normal (allowing the soil to dry out slightly between waterings).”
SDSU does not split that advice by flowering stage. Its cue is: “When the top one-third of the soil feels dry to the touch, and the pot feels light when lifted, go ahead and water your cactus. ... After 10 to 15 minutes of drainage into a pot tray, make sure to dump out the excess water.”
Light
Iowa State, SDSU, and Illinois agree on bright, indirect light.
- Iowa State: “Indoors, holiday cacti prefer bright, indirect light and temperatures between 60°F and 70°F.”
- SDSU: “All three holiday cacti species need bright, indirect light. An east-facing window, or placement in a naturally lit, bright room is ideal.”
- Illinois: “bright, indirect light” while the plant is blooming. Outdoors in summer: “If they are exposed to too much light, plants may turn pale green or become sunburnt.”
Cool nights and long darkness
Give it long, uninterrupted nights in fall: at least 12 hours of darkness (Illinois, SDSU), or 14–16 hours for most cultivars (Iowa State). Keep it cool, around 55–65°F at night. Iowa State says temperatures above 70°F prevent flowering.
The hours and the night temperatures are not the same sentence on every extension page. Read each row on its own.
| Source | Darkness | Temperature |
|---|---|---|
| Illinois | At least 12 hours of continuous darkness for 5-6 weeks. Flower buds will not set if the darkness is interrupted for too long (2+ hours). | Daytime 65–70°F and evening 55–65°F. Nighttime temperatures around 55°F may also induce blooming, regardless of night length. Temperatures below 50°F may cause flower buds to drop. |
| SDSU | Three or more weeks with 12 to 14 hours of complete darkness will cause the plants to form buds. | Nighttime temperatures near 55°F will cause bloom formation to happen more quickly. Bud formation for Thanksgiving and Christmas cacti is optimized in rooms with temperatures less than 65°F. |
| Iowa State | Most species and cultivars need 14–16 hours of uninterrupted darkness. Some cultivars may bloom with as little as 12 hours of uninterrupted darkness. | Above 70°F prevents flowering even with short days. Some Christmas and Thanksgiving cacti will bloom if kept at 55°F in fall, regardless of day length. Ideal nighttime temperatures are 60–65°F, with slightly warmer days. |
| Clemson | To flower, relocate the plant for 8 weeks to an area where it will receive 13 hours of dark daily. | — |
Easter cactus uses a different schedule
Easter cactus bud set is its own schedule. Iowa State: “In the fall, provide 14–16 hours of uninterrupted darkness and temperatures of 60-70°F for 3-4 weeks, followed by temperatures of 47-55°F for 4-6 weeks.”
SDSU says the Easter cactus will initiate blooms under warmer temperatures as days lengthen.
Why it won’t bloom, and why buds drop
Why it won’t bloom
- Clemson: “If your holiday cactus isn't flowering, it's probably related to light. ... Indoor lighting and even streetlights shining through a window can interrupt the dark cycle required for flower formation.”
- Illinois: nights that are too warm.
- Iowa State: “Holiday cactus won't bloom if exposed to artificial light at night,” including lamps, kitchen lights, or streetlights. “When the temperature exceeds 70°F, it prevents flowering.”
Why buds drop
- Illinois: “temperatures that are too high, exposure to drafts, insufficient lighting, under or overwatering, and low humidity.” Illinois also says temperatures below 50°F may cause flower buds to drop.
- SDSU: any stress, including sudden changes in temperature, light, or water.
- Iowa State: “Sudden changes can cause buds to drop.” Avoid moving the plant during bud development. Move it once the first flowers open. Cold in winter transit can also drop buds.
How to tell Christmas vs Thanksgiving vs Easter cactus
Stem edges
Illinois, Iowa State, and SDSU each describe the stem edges.
| Source | Thanksgiving | Christmas | Easter |
|---|---|---|---|
| Illinois | Pointed teeth along the outside margins that look like hooks or claws. Illinois also calls these crab cacti. | Smooth, more rounded or scalloped margins. | Rounded margins. |
| Iowa State | 2–4 upward-pointing teeth. | Scalloped stem segments without pointed teeth. | Smoother than the other types, with 4–6 slight ripples and brownish bristles at the tips. |
| SDSU | Two to four saw-toothed serrations. | More scalloped or teardrop shaped. | Very rounded edges. |
Flowers
Illinois says Thanksgiving and Christmas cacti have tubular flowers. Thanksgiving anthers are yellow. Christmas anthers are purplish-brown. Easter cacti have star-shaped flowers. Clemson matches those anther colors. SDSU also says the Easter cactus flower is star-shaped.
What is actually sold
This is an identification point, separate from the pet-safety listing later on this page. Illinois says: “Most of the 'Christmas cactuses' sold are actually Thanksgiving cacti.” Iowa State says: “Most plants sold as 'Christmas cactus' are actually Thanksgiving cactus or hybrids.”
Bloom windows
Christmas cactus bloom windows conflict. Both are listed. They are not combined into one span.
| Source | Thanksgiving | Christmas | Easter |
|---|---|---|---|
| Illinois | Late November to late December. | Late December to March. | March to May. |
| Iowa State | Mid-November to late December. | Rosy-red flowers from late November to early February. | Primarily March to May. |
Scientific names
Illinois and Iowa State print different Easter cactus names. Both are listed. Illinois prints a scientific name for the Thanksgiving cactus. Iowa State’s scientific names here are for the Christmas cactus and the Easter cactus.
- Illinois: Thanksgiving cactus, Schlumbergera truncata. Christmas cactus, Schlumbergera x buckleyi and Schlumbergera bridgesii. Easter or spring cactus, Rhipsalidopsis gaertneri.
- Iowa State: Christmas cactus (Schlumbergera × buckleyi), also known as Schlumbergera bridgesii. Easter cactus (Schlumbergera gaertneri), formerly Hatiora gaertneri and Rhipsalidopsis gaertneri.
- SDSU uses Schlumbergera gaertneri for the Easter cactus, the same genus and species Iowa State uses. Illinois uses Rhipsalidopsis gaertneri.
Is a Christmas cactus toxic to cats and dogs?
The ASPCA lists Christmas cactus (Schlumbergera bridgesii) as non-toxic to dogs and cats. If your pet eats a lot of any plant and seems unwell, call your vet or a pet poison hotline.
That sentence follows the ASPCA Christmas cactus listing. The listing’s own fields are:
- Common name: “Christmas Cactus”
- Additional Common Names: “Easter Cactus”
- Scientific Name: Schlumbergera bridgesii
- Family: Cactaceae
- Non-Toxicity: “Non-Toxic to Dogs, Non-Toxic to Cats, Non-Toxic to Horses”
- No clinical signs or toxic principles are listed.
The ASPCA page footer names (888) 426-4435 and notes a consultation fee may apply.
Not sure which holiday cactus you have, or got a sick plant?
A store tag is a weak ID. The stem-edge check above is the one Illinois, Iowa State, and SDSU describe. Plantsnap Plant Identifier by Tecmanic can identify a plant from a photo and show a confidence level. After the ID, it shows care notes. It can also spot visible problems from a photo. You can save the plant to a plant list with iCloud sync.
The product page is Plantsnap Plant Identifier. Download Plantsnap Plant Identifier by Tecmanic on the App Store.
FAQ
How should I water a Christmas cactus while it is in bloom, and after?
While it is budding and flowering, Iowa State says keep the soil evenly moist. Dryness can cause buds or flowers to drop. Illinois says the soil should be kept moist, and the plant should not sit in water. If it gets too dry while blooming, it may drop its flowers. After flowering, the two extensions do not use the same dry-down. Iowa State says allow the soil to dry completely between waterings when the plant is not in flower. Overwatering leads to limp growth and root rot. Illinois says resume watering like normal, allowing the soil to dry out slightly between waterings. SDSU uses its own cue and does not split it by flowering stage: water when the top one-third of the soil feels dry and the pot feels light, then dump excess water from the tray after 10 to 15 minutes.
How much darkness and cool night temperature does a Christmas cactus need to set buds?
Give it long, uninterrupted nights in fall: at least 12 hours of darkness (Illinois, SDSU), or 14–16 hours for most cultivars (Iowa State). Keep it cool, around 55–65°F at night. Iowa State says temperatures above 70°F prevent flowering. Illinois, SDSU, Iowa State, and Clemson each publish their own hours and night temperatures. Those figures stay with the source that printed them.
Why won’t a Christmas cactus bloom, and why do buds drop?
Clemson says if a holiday cactus isn’t flowering, it is probably related to light. Indoor lighting and even streetlights shining through a window can interrupt the dark cycle required for flower formation. Illinois points to nights that are too warm. Iowa State says a holiday cactus won’t bloom if it is exposed to artificial light at night, including lamps, kitchen lights, or streetlights, and that when the temperature exceeds 70°F it prevents flowering. For bud drop, Illinois lists temperatures that are too high, exposure to drafts, insufficient lighting, under or overwatering, and low humidity. Illinois also says temperatures below 50°F may cause flower buds to drop. SDSU says any stress, including sudden changes in temperature, light, or water. Iowa State says sudden changes can cause buds to drop. Avoid moving the plant during bud development, and move it once the first flowers open. Cold in winter transit can also drop buds.
How do I tell a Christmas cactus from a Thanksgiving cactus and an Easter cactus?
Compare the stem edges. Illinois says Thanksgiving cacti, also called crab cacti, have pointed teeth along the margins that look like hooks or claws. Christmas cacti have smooth, more rounded or scalloped margins. Easter cacti have rounded margins. Iowa State says Thanksgiving stem segments have 2–4 upward-pointing teeth, Christmas segments are scalloped without pointed teeth, and Easter segments are smoother, with 4–6 slight ripples and brownish bristles at the tips. SDSU says Thanksgiving segments have two to four saw-toothed serrations, Christmas margins are more scalloped or teardrop shaped, and the Easter cactus has very rounded edges. Illinois says Thanksgiving and Christmas cacti have tubular flowers, Thanksgiving anthers are yellow, and Christmas anthers are purplish-brown. Clemson matches those anther colors. Illinois and SDSU say the Easter cactus flower is star-shaped. Bloom windows differ by source. Illinois puts Thanksgiving from late November to late December, Christmas from late December to March, and Easter or spring cactus from March to May. Iowa State puts Thanksgiving from mid-November to late December, Christmas as rosy-red flowers from late November to early February, and Easter primarily from March to May.
Is a Christmas cactus toxic to cats and dogs?
The ASPCA lists Christmas cactus (Schlumbergera bridgesii) as non-toxic to dogs and cats. If your pet eats a lot of any plant and seems unwell, call your vet or a pet poison hotline.