Kalanchoe Care: How to Grow It and Make It Bloom Again

The kalanchoe you picked up at the supermarket — a neat dome of glossy scalloped leaves under a cushion of tiny red, orange, pink, yellow or white flowers — is Kalanchoe blossfeldiana, and it is one of the most underrated houseplants there is. Most people treat it as a disposable pot of colour and bin it when the flowers fade. That's a shame, because it's a tough Madagascan succulent that will live for years and flower again every winter, if you know its one secret: like a poinsettia or a Christmas cactus, it counts the hours of darkness.

Light

Kalanchoe wants real light — more than most flowering houseplants. A south- or west-facing windowsill is ideal; it will take a few hours of direct sun happily, though fierce midday summer sun through glass can scorch the leaves, so pull it back a touch in high summer. In too little light the tell-tale signs appear fast: stems stretch, the gaps between leaves widen, leaf edges lose their reddish tint, and flowering fizzles out. A leggy, flowerless kalanchoe is nearly always a dark-corner kalanchoe.

Watering

Treat it like the succulent it is. The thick, waxy leaves store water, so the plant would far rather be too dry than too wet. Water only when the top half of the compost is dry — roughly every 10–14 days in a warm bright room, and as little as monthly in winter — then water thoroughly until it runs from the drainage holes and empty the saucer. Try to keep water off the foliage and out of the dense flower head; wet leaves in a cool room invite mildew and rot.

Warning: overwatering is the number one kalanchoe killer. Soft, translucent, yellowing leaves and a blackening stem base mean the roots are rotting in soggy compost. If you catch it early, unpot the plant, trim off brown mushy roots, and repot into barely moist, gritty succulent mix — then hold off watering for a week or two.

Temperature, soil and feeding

Normal room temperatures suit it perfectly — 15–25°C is the comfort zone, and anything reliably above 10°C is survivable. It is not frost-hardy at all, so if it summers outdoors on a patio or balcony (which it enjoys), bring it in well before the first cold nights. Pot it in a free-draining mix — cactus compost, or houseplant compost cut with a third grit or perlite — in a pot with drainage holes. Feed monthly at half strength from spring to late summer; a hungry kalanchoe flowers better than an overfed one.

Deadheading and the after-bloom trim

A kalanchoe can stay in flower for six to eight weeks or more. As individual blooms fade, pinch them out to keep the display tidy and encourage side buds to open. Once the whole flush is finished, cut the spent flower stems back to the first pair of good leaves and give the plant a light all-over trim to keep it compact. It will spend the next few months quietly growing new foliage — that's normal, not sulking.

How to make a kalanchoe rebloom

Here is the part the label never tells you. Kalanchoe blossfeldiana is a short-day plant: it forms flower buds in response to long, uninterrupted nights. In its natural rhythm that means winter flowers, and commercial growers fake it with blackout cloth to sell blooming plants year-round. You can do exactly the same at home.

• From early-to-mid autumn, give the plant around 14 hours of complete darkness every night for about six weeks — a spare room that's never lit, a cupboard, or simply a cardboard box popped over it from early evening to morning.
• During the day, return it to a bright windowsill — it still needs its 8–10 hours of good light.
• Keep it on the cool side (roughly 10–18°C) and water very sparingly during the treatment.
• Even a brief blast of lamplight in the middle of the night can reset the clock, so be consistent.
• After six weeks, tiny buds appear in the growing tips. Go back to normal care and enjoy the show a few weeks later.

Tip: a cool, bright, rarely used bedroom does most of this automatically in autumn — the nights are naturally long and nobody switches the lights on. Many kalanchoes rebloom there with no cardboard-box theatrics at all.

Propagation

Kalanchoe roots readily from cuttings in spring or summer. Snip a 5–8 cm shoot, remove the lowest leaves, let the cut end dry for a day or two so it callouses, then push it into barely moist gritty compost. Kept warm and bright, it roots in two to three weeks. Single leaves will also root, more slowly. It's the easy way to replace an old woody plant with a fresh, compact one.

Common problems

• No flowers for months: usually evening room lighting keeping the nights short, or not enough daytime light. Run the six-week dark treatment.
• Leggy, stretched growth: too little light. Move it to a brighter sill and trim it back into shape in spring.
• Soft, mushy yellow leaves: overwatering — check the roots and let the compost dry fully.
• White powdery patches on leaves: powdery mildew, encouraged by wet foliage and still air. Improve airflow and keep the leaves dry.
• Fine white fluff in leaf joints: mealybugs — dab them with a cotton bud dipped in rubbing alcohol and repeat weekly.

Warning: kalanchoe contains bufadienolide cardiac glycosides and is toxic to cats and dogs — the flowers included. Nibbling typically causes drooling and vomiting, but a large amount can affect the heart, so keep it out of reach of pets or choose a pet-safe flowering plant instead.

Not sure whether yours is a kalanchoe at all, or whether those soft leaves are rot or thirst? Photograph it with PlantMe — the app identifies the plant and its problem in seconds, and tells you exactly what to do next.