Around Thanksgiving you may notice a plant with cheery, bright flowers and thick glossy green leaves popping up in the houseplant displays of retail stores. These are Kalanchoe blossfeldiana, commonly known as Flaming Katy, for the hot orange- red color of the original species or Christmas kalanchoe. You may even notice Kalanchoe with clusters of what appear to be tiny roses. This is a very double flowered form of the original kalanchoe and is sold as Calandiva®. Kalanchoe in bloom are also sold in some nurseries in the spring for patio containers.
Christmas Kalanchoe flowers come in a wide variety of colors from including, red, pink, yellow, orange, purple and white. The flowers have 4 petals and are clustered at the end of flower stems. Even a small plant will flower profusely. The leaves are dark green, thick and glossy, with scalloped edges. The plants are attractive even when not in bloom.
The newer Calandiva is considered to be a new species by some and simply a double flowered version of Christmas kalanchoe by others but in either case it is quite stunning. The flowers look like tiny cabbage flowered roses in clusters. They also come in a variety of colors including blends of colors. The leaves of this kalanchoe seem to be a bit broader than Christmas kalanchoe.
Other species of Kalanchoe you may occasionally come upon are Kalanchoe synsepala ‘Gremlin’, ‘Kalanchoe Tormentosa’ or Kalanchoe beharensis. These are primarily grown for their striking succulent foliage. ‘Gremlin’ has thick, broad green leaves with a red edge and produces “pups” on long stems. K.tormentosa, also called Panda bear plant, has smaller fuzzy, gray green foliage edged in red and K. beharensis has blue-green foliage.
Culture of kalanchoe
Kalanchoe are warmth loving succulents and do not tolerate frost. While a summer outside is much appreciated and often initiates bloom, they must be brought inside before temperatures fall into the lower 40’s at night. And they should not be put outside again until after all danger of frost has passed. When buying a kalanchoe in colder weather make sure that the plant is protected by a bag going to the car and don’t leave it in the car while you shop.
Kalanchoes need good drainage in the container they live in and a good, lightweight potting soil. Clay pots are excellent but if your watering is careful any pot with good drainage will do. The pots should be allowed to dry on the surface a bit between watering but don’t let the plant wilt. Don’t overwater; plants that are kept too wet either get root rot or are more likely to pick up fungal diseases.
Most kalanchoes are bought as small plants but if they are happy in their new homes they grow quickly. You may need to transplant the plant into a bigger pot several times. Pots that are wider than they are deep work well. Happy plants can fill a 12 inch container in a year or two.
Indoors kalanchoe likes bright light, the Christmas kalanchoe does well in a south window but Calandiva should not be placed in strong southern exposures unless they are a foot or so from the window. In the winter west windows are fine but watch the exposure as late spring approaches and move the plants if they seem to be drying out on the leaf tips. East facing windows or even unobstructed north windows that aren’t too cold are fine. Supplemental lighting can be used if your natural daylight is limited.
Kalanchoe synsepala plants respond to the amount of light they receive by adjusting the angle of their leaves. In lower light conditions the leaves will flatten out to give leaf surfaces maximum exposure. In bright sunlight the leaves will be in a more upright position, so less leaf surface is exposed. The leaf edges of this plant will be redder in moderate light.
When you move your kalanchoe plants outside in the spring do not place them in direct sunlight immediately, even if they were in a southern window. This may scorch the leaves and even cause death. Place them in a shady location and over the space of two weeks or so move them gradually into brighter light. They will thrive in partly shady locations outside or after acclimatization, in a sunny area. Plants will need more watering in sunny areas.
Kalanchoe have moderate fertilization needs. Fertilize through the summer and through the bloom time in late fall and early winter with a fertilizer formulated for blooming plants as directed on the label. When the plant goes through a pause in bloom in late winter – early spring you can quit fertilizing until growth resumes in warmer weather. Since some kalanachoe are manipulated to bloom at other times of the season – such as for late spring for container plant sales- you may have to adjust your fertilization schedule. Fertilize when in bud and bloom and during active growth periods.
Getting kalanchoe to bloom again
Kalanchoe is a short day bloomer. That means they typically bloom in late fall and early winter if natural daylight conditions are used. A summer outside with gradually decreasing light and temperatures is usually all that’s needed to start the plant blooming. Nurseries manipulate light conditions to have kalanchoes in bloom at several times during the year.
If your kalanchoe doesn’t spend a summer outside you may need to put a box or cover over it in fall when natural darkness falls (take the box off each morning) or keep it in a room where artificial lights aren’t used often. Plants need about 14 hours of darkness for about 6 weeks to initiate buds. Cooler temperatures at night than during the day are also helpful but don’t drop the temperature below 50 degrees.
As soon as buds appear on the plant you don’t need to worry about day length anymore and once blooming begins plants may bloom for 6 weeks or so. Some plants are less attuned to day length than others and will have several cycles of bloom each year. Keep kalanchoe flowers trimmed off as they finish blooming.
Propagation of kalanchoe
Kalanchoe can be started from seeds but gardeners will have a hard time finding seeds for sale. But kalanchoe are pretty easy to start from cuttings. Take stem cuttings of a few inches long and let them dry for a day. Rooting hormone can be used but isn’t necessary. Then insert the cuttings in a seed starting mix and keep the pots moist but not overly wet at a temperature around 70 degrees. The cuttings will usually root within 3 weeks.
It’s a good idea to start cuttings in early summer so by fall the plants will be blooming size, but cuttings can be taken at any time. The “pups” or aerial plantlets that form on Kalanchoe synsepala can also be rooted to make new plants.
The most common problem with kalanchoe is keeping them too wet. In too moist soil or high humidity kalanchoe can develop powdery mildew. In kalanchoes this takes the form of yellowish spots and rings on the leaves, stunting and no flowering. Increase air circulation, drop humidity and let plants dry between watering and use a plant fungicide to correct the problem.
Occasionally kalanchoes develop scale or mealy bugs. Scale looks like brown bumps on leaves and stems and mealy bugs are white, fluffy bits in the stem joints. These insects cause yellowing leaves and poor growth and flowering. Plants with scale may leave a sticky residue around them that comes from the insects droppings. In many cases these insects can be removed by hand, scales can be scrapped off with your fingernail, wipe off mealy bugs with a soapy cloth. If the problem continues use a systemic houseplant insecticide on the plants.
Whenever you see a nice Kalanchoe plant snatch it up. These tender perennials make an excellent houseplant and are in bloom for months. They are easy to care for and grow into large, attractive plants with just a little care. In the summer they make excellent container specimens and some gardeners have even used K. blossfeldiana, as bedding plants.
Here are some additional articles you may want to read.
How to make Houseplants interesting
Caring for a Norfolk Island Pine
How to collect and store common garden seeds.
You can read the authors weekly garden blog here.