Kalanchoe (Kalanchoe blossfeldiana) is a popular houseplant typically available for sale during late winter and spring months. It is a durable flowering potted plant requiring very little maintenance in the home or office. It has dark green, thick waxy leaves with scalloped-edges and small, four-petaled flowers in clusters held above the foliage. It is also available in a double flowering variety with as many as 26 petals per bloom. Kalanchoe brightens the indoors with flowers in various shades of red, magenta, pink, orange, yellow and white. It is native to Madagascar and was introduced in 1932 by Robert Blossfeld, a German hybridizer.
Kalanchoe grows best in full sun and a well-drained potting media. Kalanchoe will tolerate bright indoor light levels well. However, plants tend to get spindly in low light conditions. Kalanchoe can be damaged by over watering. Allow the soil to dry slightly between waterings. Fertilize actively growing plants with any houseplant fertilizer once a month. Ideal temperatures are 45-65 °F at night and 50-70 °F during the day. Cool night temperatures prolong flower life.
With good care, kalanchoes may be grown to rebloom the next season. After flowering, shift the plant to a slightly larger pot. Kalanchoes are succulents that grow best in a well-drained and well- aerated potting soil, such 60% peat moss and 40% perlite. Cut back tall growth and old flower stems. Keep well watered in a sunny, warm window. After danger of frost, move outdoors to a bright, lightly shaded spot for the summer. Gradually adjust them to outdoor conditions, so tender leaves will not burn. Bring back indoors before the first frost or 3 months before desired bloom time.
Kalanchoes, like poinsettias, require short day lengths (long nights) for flower bud development. Natural day lengths between October 1 and March 1 allow flower buds to form. During this time, keep the plant in a room where lights are not turned on during the naturally dark hours or control day length by placing the plant in a closet in late afternoons and then bringing it out to a high light environment each morning. About six weeks of natural winter day lengths are required for flower buds to form. Natural winter day lengths will supply kalanchoe with a 14 to16-hour night period. Temperatures above 80 °F during the long night period can result in a “heat delay”, inhibiting flower development. After the flower buds are large enough to be seen above the foliage, day length is no longer crucial. At this time, place plants in any location regardless of night lighting. Plants exposed to naturally short day lengths in early October should begin flowering by January (i.e. approximately 12 weeks from start of long nights).
Start with clean and sterile containers and rooting media. A 6- to 8-inch plastic pot can be used to root several cuttings. Recycled pots should be washed thoroughly using a household cleaner and disinfectant. A good rooting medium consists of 50% peat moss and 50% perlite. Normally, peat moss and perlite don’t need sterilization when new. Propagate from herbaceous stem cuttings in spring or early summer. Use vegetative shoots not flowering shoots for best rooting. Terminal cuttings for propagation should be two- to three-inches long with two pairs of leaves. Remove the bottom leaves from the cutting. No rooting hormone is needed. Allow the cutting to callus for several days before inserting into the rooting medium. Place the pot indoors in bright, indirect light and in a closed large plastic bag to maintain high levels of humidity. Cuttings should be established enough to transplant in 14 to 21 days.
In the home, plant diseases are rarely a problem. Too much or too little water and insects are the main problems. Root rot usually results from a soil mix that does not drain quickly or from overly frequent watering. Do not let plants sit in water. For more information, please see HGIC 1459, Indoor Plants – Watering.
Powdery mildew is another possible disease problem for kalanchoe. Powdery mildew can be difficult to recognize on kalanchoe because only fine webbing will develop. Leaves may be mottled and have yellow spotting, dead flecks, line or ring spot patterns. Plants may be stunted and not flower. To prevent powdery mildew allow for plenty of air flow around plant material. Potassium bicarbonate, such as Bonide Remedy, can be used on kalanchoe to help control powdery mildew. For more information, please see HGIC 2251 House Plant Diseases & Disorders.
Mealybugs, aphids and brown scale are the most common insect pests of kalanchoe. Isolate plants that are infested. Control mealybugs by wiping them off with alcohol using a cotton swab. Brown scale can be removed by scraping them off. Aphids can be removed by hand. For more information, please see HGIC 2252, Common Houseplant Insects & Related Pests.