The little-known kalanchoe is the firecracker of houseplants.
Kalanchoe’s colors burst with unexpected vibrancy in the dead of winter, said University of Missouri Extension horticulturist David Trinklein.
“Kalanchoes are the Energizer Bunny of succulents,” said Trinklein. “Their flowers just keep going and going and going.”
There is nothing shy about kalanchoe’s flamingo-dancer shades of yellow, orange, red, pink and magenta. Its flowers are in-your-face neon bright and they just will not go away. Few houseplants bloom for as long or as vividly as the kalanchoe.
Additionally, their fleshy, glossy-green leaves with scalloped margins offer visual interest, even when not in bloom. “Kalanchoes really do offer the best of both worlds,” Trinklein said.
Most kalanchoes are native to Madagascar and tropical Africa. One species, Kalanchoe daigremontiana, reproduces viviparously, bearing copious numbers of plantlets along the edges of its leaves. The plantlets eventually drop off and take root around the base of the main plant. Sometimes called “mother-of-thousands,” it reproduces so prolifically that commercial growers often consider it a pest.
The most colorful and well-known kalanchoe is florists’ kalanchoe. It enjoys a well-drained growing medium and bright light. Plants tend to get spindly under low-light conditions. Florists’ kalanchoe prefers a night temperature of about 60 degrees Fahrenheit and day temperatures of about 70 degrees. Temperatures over 75 degrees tend to delay or reduce flowering.
Because they are succulents, kalanchoes tolerate moisture stress. Their fleshy leaves are covered with a thick cuticle that prevents water loss. Therefore, allow the growing medium to dry before watering, said Trinklein. If you use a flowerpot with a saucer, drain any excess water from the saucer so it is not wicked back into the medium.
Florists’ kalanchoe is relatively easy to rebloom. After the danger of frost has past, move plants outdoors in light shade or indirect sun. Cut plants back to about half of their height if they have become tall and leggy. Fertilize during the summer every two to three weeks with a houseplant fertilizer according to label directions.
Like poinsettia, kalanchoe requires short days and long nights to develop flowers. For Christmas blooming, start short-day treatment around the middle of September, after plants have been moved back indoors. A dark period of 14 hours results in the most blooms. The plants cannot be exposed to any light in during the dark period. After the daily dark period, exposure to light for the remaining 10 hours in the day is required if the plant is to bloom.
Feed and water sparingly during flower induction. Plants should bloom in about six weeks.
Kalanchoes have few insect or disease problems. Overwatering results in crown rot that can lead to sudden plant death. Powdery mildew can be a problem when kalanchoes grow in greenhouses. However, the relative humidity of the average home is too low for the disease to be a problem.
Propagation of kalanchoes is relatively easy. Remove flowers from stems you plan to use for propagation. Use stem-tip cuttings 2-3 inches in length. Stick the cuttings in a porous germination medium such as a mixture of peat and vermiculite. Maintain a high relative humidity around the cuttings. Rooting should occur within two to three weeks.
Trinklein said kalanchoe’s beauty comes with a risk. Most species contain cardiac glycosides that are toxic to many animals, including dogs and cats. Flowers contain more glycosides than other parts of the plant. The U.S. Food and Drug Administration recommends keeping kalanchoes away from household pets.