Kalanchoe is often sold in flower and binned once the flowers fade. It doesn't need to be. It's a short-day plant: it sets flower buds only after a run of long, dark nights. On a windowsill in a room with the lights on every evening, it never gets them. Give it proper darkness in autumn and it will flower again, usually in winter.
01At a glance
- The trigger: long, unbroken nights of about 14 hours.
- For how long: about six weeks, starting in early autumn.
- The enemy: lamp light in the evening, which cuts the night short.
- The rest of the year: grow it as a succulent in bright light, and let it dry between waterings.
- After flowering: cut off the old flower stems and keep it growing.
02Why it stopped flowering
A University of California growers' guide to Kalanchoe blossfeldiana, hosted by NC State Extension, says most varieties need a minimum dark period of about 13 hours a night to start forming flowers. Clemson Extension says about six weeks of 14- to 16-hour winter nights are needed for buds to form. More short days can mean more flowers: the same guide found the display kept improving with up to at least eight weeks.
By mid-autumn, British nights are long enough on their own, and they keep lengthening to midwinter. The problem is the house lights. A plant in a living room gets a lit evening every night, so its "night" never runs long enough.
03Step by step: autumn reflowering
- Start in late September or early October. Clemson says plants that start long nights in early October should flower about 12 weeks later.
- Choose a spare room, landing or porch that stays bright by day and isn't lit in the evening. It must still be above the plant's minimum, about 10°C.
- Or use the cupboard method. Clemson suggests moving the plant into a dark cupboard in late afternoon and back into bright light each morning. Aim for about 14 hours of darkness. Be consistent: miss days and you lose ground.
- Keep it in good light by day. Darkness at night doesn't replace light by day.
- Water sparingly. Let the compost dry between waterings.
- Keep it cool rather than hot. Clemson warns that temperatures above about 27°C during the long-night period can delay flowering. Indoors in Britain that's rarely a problem, but don't park it next to a radiator.
- Stop once you see buds. Clemson says once buds show above the leaves, day length no longer matters. Bring it back to its usual windowsill.
04After it flowers
- Cut back the old flower stems once the flowers fade, as Clemson advises, along with any tall, leggy growth.
- Pot it on if needed. Clemson suggests a slightly larger pot after flowering, in a free-draining mix. Our kalanchoe profile recommends a cactus and succulent compost or houseplant compost cut with grit.
- Give it a sunny spot through spring and summer. If you move it outside for summer, Clemson suggests a bright, lightly shaded spot, getting it used to the sun gradually so the leaves don't scorch. Bring it in well before the first frost.
- Feed lightly in growth. A weak feed monthly in spring and summer is plenty.
05Watering: treat it as a succulent
The thick leaves store water. Water thoroughly, then let the compost dry before you water again. Overwatering kills far more kalanchoes than neglect.
06Why no flowers?
- Leggy, stretched, no buds: too little daytime light, or lamp light at night. Usually both.
- Lots of leaves in autumn, still no buds by December: the nights weren't long or unbroken enough. Check for a hall light, a street lamp or a TV.
- Buds formed, then stalled: too warm. Move it somewhere cooler.
- Flowers fading quickly: a warm room. Clemson notes that cool nights help the flowers last longer.
Before placing it where children or pets can reach, check the safety flags on our kalanchoe profile.
How we checked this
Every care and safety claim on this page is verified against horticultural and veterinary sources.
Sources: Clemson Cooperative Extension — Kalanchoe · NC State Extension (HortScans) — Kalanchoe blossfeldiana 'Tetra Vulcan': suggestions for growing as a pot plant
Checked 8 October 2026. If our advice ever conflicts with the RHS, believe them and tell us.