How-to Guide
Kalanchoe: Care, Watering, and the Short-Day Trick for Reblooming
The short answer
Kalanchoe blossfeldiana grows best in full sun and a well-drained potting medium, and it is easily damaged by overwatering: Clemson Extension says to allow the soil to dry slightly between waterings and never leave the pot in standing water.
To make it flower again, give it darkness, not fertilizer. Kalanchoes are short-day plants: flower buds form only with about six weeks of long nights, a 14 to 16 hour dark period each day, which natural winter day lengths between October and March provide if the plant is not exposed to evening lamp light.
What Kalanchoe Is
Kalanchoe blossfeldiana, the florist kalanchoe or flaming Katy, is a flowering succulent sold in bloom year-round. The scalloped fleshy leaves mark it as a succulent; the clustered flowers are the reason people buy it, and the reason most questions are about getting them back.
Light and Temperature
Full sun and a well-drained medium produce the best plants; in low indoor light kalanchoes tend to get spindly. Clemson gives ideal temperatures of 45-65 F at night and 50-70 F by day, and notes that cool night temperatures prolong flower life.
Watering
Kalanchoe can be damaged by overwatering. Allow the soil to dry slightly between waterings and never let the pot sit in standing water. The thick leaves buffer drought far better than they tolerate soggy roots.
⚠ Root rot from poor drainage is a leading kalanchoe killer. Empty the decorative foil sleeve or saucer after every watering.
Soil
Clemson's recommended growing mix is 60% peat moss and 40% perlite; any fast-draining succulent mix in a pot with drainage holes will serve.
How to Make Kalanchoe Rebloom
- 1Wait for the natural short-day window — Flower buds develop under short days and long nights; conditions between October 1 and March 1 naturally induce flowering.
- 2Give 14-16 hour nights for about six weeks — Clemson: about six weeks of natural winter day lengths, with a 14 to 16 hour night period, are required for flower buds to form. Keep the plant away from lamps and room light in the evening, or cover it.
- 3Keep nights cool — Cool nights in the 45-65 F range support bud set and make the flowers last longer.
Propagation
Take herbaceous stem cuttings two to three inches long with leaf pairs, allow them to callus for several days, then insert them in a 50% peat moss / 50% perlite medium. Cuttings are usually established enough to transplant in 14 to 21 days.
Problems and Pet Safety
- Root rot from poor drainage.
- Powdery mildew.
- Mealybugs, aphids, and brown scale.
- Spindly growth: not enough light.
→ Kalanchoe is commonly listed as a plant of concern for cats and dogs. Check the ASPCA toxic and non-toxic plant list before keeping one where pets can nibble it.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- Clemson Cooperative Extension HGIC — Kalanchoe — Full sun; dry slightly between waterings, no standing water; 60/40 peat-perlite mix; 45-65 F nights; six weeks of 14-16 hour nights for bud set; stem cutting propagation with callusing; root rot, powdery mildew, mealybugs/aphids/scale.