Identity & taxonomy
- Scientific name
- Kalanchoe blossfeldiana Poelln.
- Family
- Crassulaceae
- Genus
- Kalanchoe
- Order
- Saxifragales
- IUCN status
- Not Evaluated (NE)
- Wikidata
- Q161122
- Bryophyllum blossfeldianum (Poelln.) P.I.Forst. (recent split — APG IV puts Bryophyllum back inside Kalanchoe)
- Kalanchoeen
- Flaming Katyen
- Christmas kalanchoeen
- Madagascar widow's-thrillen
- Florist kalanchoeen
- Eldkalanchoesv
- Ildkalanchoeno
- Ildkalanchoeda
- Liekkikalankoefi
- Flammendes Käthchende
Madagascar (endemic to dry rocky habitats in the central highlands)
How to identify it
Growth habit. Compact upright succulent shrub with thick branching stems rising from a woody base. Flower stems emerge from the centre of leaf rosettes at the stem tips, lifting flat-topped umbels of 20–60 small flowers above the foliage. After bloom the flower stems die back and new vegetative growth emerges from below. Older specimens become slightly leggy over 2–3 years.
Leaves. Leaves are opposite, fleshy, glossy, dark mid-green, ovate to obovate, 5–8 cm long, with prominently scalloped or crenate margins (rounded teeth, not pointed). Leaf surface is smooth and slightly waxy. Some cultivars develop a red flush along the leaf edge when grown in strong light.
Flowers. Dense flat-topped umbels (cymes) of 20–60 small four-petalled tubular flowers, each roughly 1 cm across. Wild type is brick-red; cultivated forms span red, pink, orange, yellow, white, salmon, and bicolour. Calandiva-series doubles have layered rose-shaped petals. Flowers are produced in response to long nights (short days) and last 6–10 weeks per cycle.
- Thick fleshy succulent leaves with distinctive scalloped (crenate) margins.
- Dense flat-topped umbels of tiny four-petalled flowers in jewel-bright colours.
- Compact upright bushy habit on woody stems — does not trail or climb.
- Sap is clear and watery, not milky — distinguishes from euphorbia lookalikes.
- Flowers develop in response to short days; commercial growers force bloom for autumn–winter sale.
Commonly confused with
Mother of thousands / devil's backbone
Daigremontiana has long narrow lance-shaped leaves with plantlets along the margins; blossfeldiana leaves are ovate with scalloped (not plantlet-bearing) edges. Daigremontiana flowers are pendant tubes, not flat umbels.
Panda plant
Tomentosa has fuzzy silver-grey leaves with brown-tipped edges; blossfeldiana leaves are smooth, glossy, and mid-green.
Jade plant
Both Crassulaceae succulents, but jade has small thick oval leaves with smooth margins on tree-like woody stems and tiny white star flowers; blossfeldiana has scalloped leaves and showy coloured umbels.
Tree houseleek
Aeonium grows as flat rosettes at branch tips; blossfeldiana leaves are paired along the stem with no rosette structure.
Care
Light
Bright direct or indirect — needs 4+ hours of sun for re-bloom.
Place at a south, east, or west window with at least 4 hours of direct sun daily. Without strong light the plant may survive but will refuse to set new flower buds. The Calandiva double cultivars hold colour better than the older single-flowered types in lower light, but neither will rebloom in dim conditions.
Seasonal: Nordic apartments above ~55°N: a full-spectrum grow light is essential for repeat bloom from October through March, since the plant simultaneously needs strong light for vegetative growth AND long uninterrupted nights for flower induction (see Reblooming section below).
Water
Let the soil dry completely between waterings.
Kalanchoe is a true succulent — water once every 10–14 days in summer and once every 3–4 weeks in winter. Stick a finger 3 cm into the soil before watering; only water if it is bone dry. Water thoroughly until runoff and empty the saucer. Standing water in the saucer is the leading cause of root rot in this species. During bloom, water slightly more frequently (the plant uses more water during flowering) but the drying-between rule still applies.
Seasonal: Cut watering by half from October to February.
Soil
Cactus and succulent mix with extra perlite.
Use a commercial cactus/succulent mix straight from the bag, or cut peat-free potting soil 1:1 with perlite or coarse sand. The most common potting failure is using a moisture-retentive houseplant mix straight — the rootball never dries out and rot follows. The supermarket pot the plant arrived in is fine for the first 6–12 months; repot only when roots fill the pot.
Humidity
30–50 %; tolerates very dry indoor air.
One of the most humidity-tolerant popular flowering plants. Even the dry winter air of a heated Nordic apartment poses no problem. Misting is unnecessary and actually harmful — water sitting in the leaf rosette and on the flowers promotes botrytis (grey mould) during the bloom period.
Temperature
15–24 °C; cool nights help bloom.
Comfortable in normal room temperatures. Slightly cooler nights (12–16 °C) during the bud-setting period help flower initiation. Do not place near a frost-prone window in winter — leaves blacken at 5 °C and rot at 0 °C.
Fertilizer
Half-strength balanced or bloom-boosting feed monthly during active growth.
Use a balanced (10-10-10) or bloom-formula (5-10-10) liquid feed at half label rate every 4 weeks from February through September. Stop feeding entirely 6 weeks before the desired bloom period — blooming kalanchoe responds poorly to high nitrogen, which encourages leaf growth at the expense of flowers.
Seasonal: No feeding during the dormancy/bud-setting weeks of October–November.
Pruning
Deadhead spent flower stems and pinch tips to keep compact.
After each bloom cycle, cut spent flower stems back to the leaf rosette; this redirects energy to new growth. Pinch growing tips in spring to encourage branching and a tighter bushy form. Mature plants tend toward legginess after 2–3 years; a hard prune to 10 cm above soil level in spring restores compact form, with cuttings used for propagation.
Repotting
Every 2–3 years in spring; prefers a snug pot.
Move up by one pot size (2–3 cm wider) in fresh succulent mix. Kalanchoe prefers to be slightly pot-bound — over-potting (large pot, small rootball) holds excess moisture and triggers rot. Spring is the best window after the spring bloom is finished.
Stem cutting
easy~2–4 weeksTake a 7–10 cm tip cutting in spring or summer. Strip the bottom pair of leaves. Let the cut end air-dry for 24–48 hours to seal (essential — fresh wet cuttings rot). Insert into damp succulent mix and keep in bright indirect light. Do not bag — succulents need airflow. Roots emerge in 2–4 weeks.
Leaf cutting
easy~4–8 weeksTwist a healthy leaf off the stem (the entire leaf base must come away cleanly). Let it dry for 2–3 days, then lay it on the surface of damp succulent mix. New rosettes emerge from the leaf base in 4–8 weeks. The original leaf eventually withers as the new plant takes over.
Cultivars
'Calandiva' series
Double-flowered cultivar group with rose-shaped blooms in red, pink, white, yellow, and orange. The dominant supermarket cultivar since the 2000s.
'Queen' series
Compact plants with very long flower stems and large simple-flowered umbels. Bred for the cut-flower market as well as potted display.
'Wendy'
Bryophyllum-style cultivar with pendant bell-shaped flowers in pink-purple, on slightly arching stems. Distinct from the typical upright florist form.
'Tessa'
Pendant-flowered cultivar with tubular orange-red blooms; suited to hanging displays. Like 'Wendy', a Bryophyllum-flower-form cultivar.
Common problems
Plant doesn't rebloom after the first cycle
Symptom
After the supermarket flowers fade, the plant produces healthy leaves for a year but never sets buds again.
Cause
Kalanchoe is a short-day plant — flower buds form only when nights are uninterrupted dark for 14+ hours, simulating natural autumn day-length cues. In a typical home with evening lamps, ceiling lights, or street-light bleed, the plant never receives enough darkness.
Fix
Starting 6 weeks before the desired bloom date, give the plant 14 hours of complete darkness per night (cover with a cardboard box or move into a dark closet from 6 PM to 8 AM). Even a few minutes of light during the dark period resets the cycle. After 6 weeks of dark treatment, buds appear; resume normal light and the plant blooms 4–6 weeks later. Reduce nitrogen feeding throughout this period.
Mushy black stem at the soil line
Symptom
Lower stem darkens, softens, and the upper plant collapses inward; soil is wet.
Cause
Stem rot from overwatering. Kalanchoe is a true succulent and does not tolerate wet feet.
Fix
Take a healthy tip cutting from above the rot, let it dry for 48 hours, and root in fresh succulent mix. Discard the rotted stem and old soil. Use a smaller pot, faster-draining mix, and water only when soil is bone-dry going forward.
Full guide: Mushy Black Stems on Houseplants: Stem Rot vs Cold Damage vs SunburnLeggy stretched stems with sparse leaves
Symptom
Stems elongate dramatically with wide gaps between leaves, leaning toward the light source.
Cause
Insufficient light. Kalanchoe stretches (etiolates) rapidly in low light.
Fix
Move to a brighter position with 4+ hours of direct sun. Hard prune leggy stems to 10 cm above soil in spring; new compact growth emerges from below the cut. Use the cut tops as cuttings.
Full guide: Why Is My Plant Leggy? Causes of Stretching and How to Fix ItFlowers turning brown and mushy mid-bloom
Symptom
Blooms develop grey-brown patches, become slimy, and collapse before the bloom cycle finishes.
Cause
Botrytis grey mould — typically from misting, water sitting on flowers, or cold humid air.
Fix
Stop misting entirely. Cut off all affected flower clusters. Improve airflow and lower humidity. Avoid placing the plant in cold, damp positions such as bathrooms or near unheated windows in winter.
Full guide: Powdery Mildew on Houseplants: Identify & Treat the White DustCat or dog vomited after chewing the plant
Symptom
Vomiting, drooling, diarrhoea, lethargy, irregular heartbeat — escalating over hours.
Cause
Bufadienolide cardiac glycosides — the same toxin family as foxglove (Digitalis). Even small ingested amounts can affect a small cat or dog.
Fix
Treat as a veterinary emergency. Contact your vet or pet poison control immediately. Do not induce vomiting at home. Take a sample of the plant for identification. Remove the plant from any home with cats, dogs, or curious children — kalanchoe is one of the more dangerously toxic common houseplants.
Full guide: My Cat or Dog Just Ate a Houseplant — What to Do Right Now- Mealybugs
- Aphids (on flower stems)
- Scale (rare)
- Root rot (Pythium, Phytophthora)
- Powdery mildew
- Botrytis grey mould (on flowers in damp conditions)
Toxicity & safety
Ingestion causes oral irritation, vomiting, abdominal pain, and in larger doses cardiac arrhythmias. Sap can cause skin irritation in sensitive individuals. Children should not handle the plant unsupervised.
Mechanism: Bufadienolide cardiac glycosides (kalanchoside, bersaldegenin-derivatives); same mechanism as Digitalis purpurea (foxglove).
Kalanchoe — North Carolina Extension Gardener Plant ToolboxVomiting, diarrhoea, depression, drooling. In larger ingestions — abnormal heart rhythm, weakness, collapse. Can be fatal in small cats with significant ingestion.
Mechanism: Bufadienolide cardiac glycosides disrupt the sodium-potassium pump in cardiac cells.
Kalanchoe — ASPCA Toxic and Non-Toxic PlantsVomiting, diarrhoea, depression. In larger ingestions — abnormal heart rhythm, weakness, collapse. Can be fatal with significant ingestion.
Mechanism: Bufadienolide cardiac glycosides disrupt the sodium-potassium pump in cardiac cells.
Kalanchoe — ASPCA Toxic and Non-Toxic PlantsHow to make a kalanchoe rebloom — the photoperiod trick
Kalanchoe blossfeldiana is what botanists call a quantitative short-day plant: flower bud formation is triggered by long uninterrupted nights, mimicking the autumn day-length signal in its native Madagascar habitat. Commercial growers exploit this by manipulating greenhouse blackout schedules to force bloom on demand. In a typical home, the plant rarely receives long enough uninterrupted darkness — evening lamps, ceiling fixtures, and even street-light bleed through curtains all disrupt the dark period and reset the bud-induction clock.
The reliable home protocol: starting 6 weeks before your desired bloom date, give the plant 14 hours of complete darkness every night. The simplest method is a cardboard box or opaque bin placed over the plant from 6 PM to 8 AM, or moving it into a dark closet at night. Even one or two minutes of light during the dark period resets the cycle, so be strict. After 6 weeks of consistent dark treatment, buds appear; resume normal light and the plant blooms 4–6 weeks later. Cut nitrogen-heavy fertiliser during this period, since high nitrogen favours leaves over flowers.
Why kalanchoe is more dangerous to pets than most houseplants
Kalanchoe blossfeldiana contains bufadienolides — cardiac glycosides in the same chemical family as the digitoxin used to treat human heart failure. Like its botanical cousin foxglove, the toxin disrupts the sodium-potassium pump in heart muscle cells, producing irregular rhythms that can be fatal. Unlike the calcium-oxalate irritation that defines most popular toxic houseplants (philodendron, monstera, dieffenbachia), bufadienolides are systemically active — they reach the heart through the bloodstream, not just the gut.
Practical implication: cats and dogs that nibble a kalanchoe leaf can develop symptoms ranging from vomiting and lethargy to genuine cardiac arrhythmia within hours. Treat any ingestion as an immediate veterinary emergency rather than a wait-and-see. ASPCA and most veterinary poison hotlines explicitly flag kalanchoe as more dangerous than the typical 'mildly toxic' aroid. Households with cats or curious dogs should pick a different flowering succulent — Christmas cactus (Schlumbergera truncata) is non-toxic and offers a similar visual story.
The species is named after Robert Blossfeld, a German seed merchant who in 1932 brought specimens collected in Madagascar back to Potsdam, where horticulturalist Kurt von Poellnitz formally described it in 1934. Blossfeld's descendants still run the breeding company that produces most modern Calandiva cultivars today — almost a century of continuous breeding from a single Madagascar collection. The species was nearly eaten alive by deer in early test gardens until it was discovered that the bufadienolides making it toxic to mammals also made it almost completely deer-proof.
Frequently asked · 5
Is kalanchoe (Kalanchoe blossfeldiana) toxic to cats and dogs?+
Yes — ASPCA lists kalanchoe as toxic to cats, dogs, horses, and grazing livestock. All parts contain bufadienolide cardiac glycosides, the same toxin family as foxglove (Digitalis). Symptoms range from vomiting and diarrhoea to cardiac arrhythmia, weakness, and (in larger ingestions) collapse and death. Any ingestion is a veterinary emergency — contact your vet or pet poison control immediately. Households with pets should pick Christmas cactus (Schlumbergera) as a non-toxic alternative.
Why won't my kalanchoe rebloom?+
Kalanchoe is a short-day plant — buds form only when nights are uninterrupted dark for 14+ hours. In a typical home with evening lamps, ceiling lights, or street-light bleed, the plant never receives enough darkness. Starting 6 weeks before the desired bloom date, give the plant 14 hours of complete darkness per night (cardboard box from 6 PM to 8 AM, or move into a dark closet). After 6 weeks of dark treatment, buds appear; resume normal light and the plant blooms 4–6 weeks later. Reduce nitrogen feeding during this period.
How often should I water a kalanchoe?+
Once every 10–14 days in summer and once every 3–4 weeks in winter. Kalanchoe is a true succulent — let the soil dry completely between waterings. Stick a finger 3 cm into the soil; only water if bone dry. Use a cactus/succulent mix and never let water sit in the saucer. Overwatering is the leading cause of death; the plant tolerates a forgotten watering far better than an extra one.
Why is my kalanchoe leggy and stretched?+
Insufficient light. Kalanchoe etiolates rapidly in low light — stems elongate with wide gaps between leaves and the plant leans toward the brightest source. Move to a position with 4+ hours of direct sun. Hard prune the leggy stems back to 10 cm above soil in spring; new compact growth emerges from below the cut, and the cut tops root readily as cuttings.
Can I keep my kalanchoe outside in summer?+
Yes — kalanchoe thrives outdoors in summer in any frost-free climate, with a few days of acclimation to direct sun. Start in a partly shaded spot and move into full sun over 7–10 days. Bring inside before night temperatures drop below 10 °C in autumn. The combination of strong outdoor light and natural day-length progression often triggers reliable autumn rebloom without manual blackout.
- Indoor Succulent Care: Why Yours Is Stretching, Rotting, or Fading (and How to Fix It)
- Are Houseplants Toxic to Cats and Dogs? A Quick-Scan Safety Guide
- My Cat or Dog Just Ate a Houseplant — What to Do Right Now
- How to Save a Supermarket or IKEA Plant in Its First Month
- Why Is My Plant Leggy? Causes of Stretching and How to Fix It