Kalanchoe
Kalanchoe blossfeldiana · Flaming Katy
The cheerful blooming succulent from the supermarket checkout grew up in the cool, misty cloud forest of northeast Madagascar. It flowers on a clock, set by the length of the night. It is also genuinely poisonous to pets.
Family
Crassulaceae
Origin
Madagascar
In the wild
Highland cloud forest
Indoors
15–45 cm
Growth
Slow to moderate
With pets
Toxic
Where it's from
Northeast Madagascar
Madagascar highlands
From the Tsaratanana massif in the northeast, in cloud forest at roughly 1,600 m and above.
Cool and bright
It grew up cold and bright, despite being sold as a desert succulent.
Outdoors: zones 10–12
Frost-free regions only. A container plant brought in before frost everywhere colder.
It blooms on a clock
Kalanchoe is a short-day plant: it only sets buds after about six weeks of long nights, roughly fourteen hours of darkness, then flowers some months later. Growers clock it to bloom on cue. At home you re-bloom it by giving it total darkness each night for about six weeks. Even a brief light at night breaks the cycle.
Engineered to flower
One of the best-selling flowering pot plants on earth, worth millions to the trade each year.
Six weeks of long nights
It needs about fourteen hours of uninterrupted darkness to reset its buds.
Weeks of colour
Dense clusters of tiny flowers in scarlet, pink, orange, yellow or white last for weeks.
How to keep it
LightBright
Full sun to bright indirect light indoors. It needs strong light for colour and rebloom.
WaterLow, let it dry out
Water thoroughly, then let the soil dry between waterings. Overwatering is the number one killer.
HumidityLowTolerates dry indoor air. High humidity with poor airflow invites powdery mildew.
TemperatureWarm, above 10°CIdeal bloom-set is cool nights and warm days. Not frost-hardy.
SoilCactus / succulent mixLight, sandy, open and very well-drained.
FeedingBarelyRoughly one light feeding a year is enough. A dilute succulent feed in growth is plenty.
DifficultyEasyA forgiving succulent. Often treated as a seasonal bloomer and replaced.
With petsToxicBufadienolides, cardiac glycosides like digitalis. The flowers are the most poisonous part.
PropagationStem or leaf cuttingsLet the cut end callus, then root in gritty mix. A fallen leaf can root and form a new plant.
RepottingRarelyEvery couple of years or when crowded. Often just replaced after blooming.
What the data says
What it costs
Sold cheaply and seasonally. One of the most mass-produced flowering houseplants on earth.
$5–15
Premium double-flowered series like Calandiva run a little higher. No collector bubble here.
IUCN · Not assessed
In the wild
On millions of shelves, while its true wild self is a thin sliver of mountain forest.
Kalanchoe blossfeldiana has no current Red List assessment and the genus is not CITES-listed. The wild species is a narrow high-altitude Madagascar endemic, and Madagascar's montane forests face habitat loss, but enormous cultivation secures the plant regardless. The houseplant thrives by the tens of millions while the wild population stays a tiny endemic. Its weedy cousins Mother of Thousands and Mother of Millions are a separate, invasive plant.
When it sulks
Mushy stems, collapseStem and root rot from overwatering, the most common killer.
White powdery coatingPowdery mildew from poor air circulation or damp, crowded conditions.
No flowers, won't rebloomNot enough uninterrupted darkness. It needs about six weeks of fourteen-hour nights.
Leggy, stretched, paleToo little light.
PestsAphids, mealybugs, spider mites and scale.
Varieties & company
The varieties
Single-floweredCalandivaDouble-flowered series
Pairs with · keep apart from
EcheveriaZebra HaworthiaSnake PlantFernsCalatheaPeace Lily
A new plant, every week.
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