How to get a kalanchoe to flower again
Kalanchoe is a short-day plant: it only sets flower buds when the nights are long. That’s why a plant that arrived covered in flowers can sit green for a year in a room where the lamps go on every evening. Here’s how to get it blooming again.
- Tidy it up after flowering. Cut off the old flower stalks and trim back any tall, floppy growth. Pinch off the stem tips to keep it bushy.
- Grow it on in good light. Keep it bright through spring and summer. It can go outdoors once frost is over, in a bright, lightly shaded spot, but introduce it to the sun gradually.
- Give it long nights. It needs about six weeks of 14-hour nights in complete darkness, with bright light during the day. From early October to early March the natural nights are long enough, as long as the room stays dark after sunset. If it doesn’t, move the plant into a closet in the late afternoon and bring it back to the light each morning.
- Keep it cool, not hot. Nights around 60°F (16°C) are ideal. Above 80°F (27°C) during the long-night weeks, flowering is delayed. Water and feed a little less during this time.
- Wait for the buds. Once buds show above the leaves, day length no longer matters and you can put it anywhere. Long nights from early October usually mean flowers by January, about 12 weeks later. Deadhead faded flowers to keep new ones coming.
Calandiva and other double kalanchoes
Almost every flowering kalanchoe you’ll find in a store is a cultivar of Kalanchoe blossfeldiana or a hybrid bred from it, sold as flaming Katy or simply “kalanchoe”.
Calandiva is a series of these with double, rose-like flowers. An ordinary florist kalanchoe has four petals per flower; the plant Calandiva was bred from, a mutant found in 1998, had 32. It’s now sold in many colors. Treat it exactly like any other kalanchoe, including the long nights it needs to rebloom.
Other double-flowered kalanchoes are sold under their own names, such as ‘Queen Jodie’ (salmon pink) and ‘Queen Lindsay’ (golden yellow).
Light
Give it a bright window with a few hours of sun. Gentle morning or winter sun is ideal; hot afternoon sun can scorch the leaves. In low light it grows leggy and spindly and won't flower well. Red leaf edges in strong light are normal, a kind of natural sunscreen.
Water
Water thoroughly, let it drain, then wait until the soil has dried before you water again. Never leave the pot standing in water. Too much water is the usual way to lose one, because the stems rot at the base. Water less in winter, when growth slows.
Soil & pots
Use a fast-draining cactus or succulent mix in a pot with a drainage hole. If it came in a decorative foil sleeve, take the sleeve off or slit the bottom so water can escape. After it flowers, move it to a pot one size bigger if the roots fill the old one.
Temperature
Normal room temperatures suit it. It flowers best with nights around 60°F (16°C) and days around 70°F (21°C), and cool nights make the flowers last longer. It can't take frost, so bring it in before nights fall to 45°F (7°C).
Is flaming Katy safe for pets?
Toxic to cats and dogs. The ASPCA lists kalanchoe (Kalanchoe spp.) as toxic to dogs and cats. The toxic compounds are bufadienolides, and the signs it lists are vomiting, diarrhea and, rarely, an abnormal heart rhythm.
Propagation
Stem cuttings root fast and are the easiest way to replace a leggy plant. Take them in spring or early summer from shoots that aren't flowering. Leaf cuttings work too.
- Cut 2–3 in (5–8 cm) shoot tips with two pairs of leaves, and pull off the lower pair.
- Leave them a few days so the cut ends callus over.
- Set them in a half-and-half mix of peat and perlite, in bright, indirect light.
- They're usually rooted and ready to pot up in two to three weeks.
Common problems
FAQ
Is kalanchoe toxic to cats and dogs?
Yes. The ASPCA lists kalanchoe as toxic to cats and dogs. It contains heart-affecting compounds called bufadienolides, and eating it can cause vomiting and diarrhea, and rarely an abnormal heart rhythm. Call your vet if a pet chews one.
Why won't my kalanchoe flower again?
It almost always needs longer nights. Kalanchoe only sets buds after about six weeks of 14-hour nights in total darkness, and a lamp switched on in the evening is enough to stop it. See the steps above.
What's the difference between Calandiva and kalanchoe?
Calandiva is a series of florist kalanchoe with double, rose-like flowers instead of the usual four petals. It's the same species, so care and reblooming are exactly the same.
Why is my kalanchoe leggy?
Not enough light. Cut it back after flowering, move it somewhere brighter, and root the tips you remove as cuttings if the old plant has gone too bare.
Can kalanchoe go outside?
Yes, for summer. Move it out after the last frost to a bright, lightly shaded spot, introduce it to sun gradually, and bring it back before nights fall to 45°F (7°C). It can live outside year-round only in zones 10–12.
Sources
- Kalanchoe blossfeldiana Poelln.: Plants of the World Online, Royal Botanic Gardens, Kew
- Kalanchoe: ASPCA Toxic and Non-Toxic Plants
- Kalanchoe blossfeldiana: Missouri Botanical Garden Plant Finder
- Kalanchoe blossfeldiana: North Carolina Extension Gardener Plant Toolbox
- Kalanchoe blossfeldiana, Christmas Kalanchoe, Madagascar Widow's-thrill (FPS-309): UF/IFAS Extension
- Kalanchoe (HGIC 1563): Clemson Cooperative Extension Home & Garden Information Center
- Kalanchoe blossfeldiana (flaming Katy): Royal Horticultural Society
- A nontraditional holiday plant, Kalanchoe: University of Illinois Extension
- A Kalanchoe by Any Other Name: Under the Solano Sun, UC Agriculture and Natural Resources
- Shaw, J.M.H. (2008). An investigation of the cultivated Kalanchoe daigremontiana group, with a checklist of Kalanchoe cultivars. Hanburyana 3: 17–79, Royal Horticultural Society