Kalanchoe (Kalanchoe blossfeldiana) cultivars: Houseplant Care

Kalanchoe is a genus of succulent plants, many of which are grown for their interesting foliage. Kalanchoe blossfeldiana cultivars, however, bear clusters of bright pink, red, orange, white or yellow flowers above their waxy, scalloped foliage. Winter hardy only in the warmest parts of the United States (USDA zones 10 and 11), these plants are grown indoors in the New York area and bring an extended season of cheerful flowers. 

Care is relatively easy but it can be hard to maintain the attractive form when kept beyond the initial flowering period; often they are kept as a temporary, seasonal decoration.  To extend their time of bloom, provide cool temperatures and full sun.

Light:

Abundant sunlight with at least four hours of direct sunlight per day will help to keep the compact growth habit. A foot or two from a south-facing window is best, but a sunny east-facing window or a west-facing window can also be fine. If you move your plant outdoors in summer it will need more protection from sunlight in a filtered shade position.

Watering and Humidity:

Water kalanchoe thoroughly when the top few inches of the soil feels dry to the touch.  If you are unsure if the soil is dry enough to water, it is better to err on the side of waiting. Empty the run-off dish after 15 minutes. After flowering, plants need reduced water and can just dry out between waterings for about a month while they take a brief rest. They are well adapted to the dry winters of the Northeast United States and do not need misting.

Temperature:

Kalanchoe blossfeldiana grows best when cool temperatures are provided. Night temperatures should be between 50° to 60°F and day temperatures between 65° to 70°F to ensure the longest possible blooming period.

Feeding:

From late spring to early winter, feed with a houseplant fertilizer twice monthly, then stop feeding from March through May.

Re-potting:

Re-pot kalanchoe in the spring, after flowering, into a rich, well-drained, porous mix of one-part sterilized houseplant potting soil, a handful of crushed stones, one-part coarse builder's sand and one-part organic matter. Kalanchoe blossfeldiana needs a pot with a drain hole.

Care after flowering:

Cut back stems and prune lightly to reshape the plant after flowers have passed. Repot your plant into one size larger container. Allow your plant to have about a 30-day rest with less water, no fertilizer and just slightly less light.

Encouraging Flowers:

Kalanchoe are winter blooming plants that are triggered to bloom when long, sunny days transition to several weeks of less sunlight. Keeping the plant outside in summer, in filtered shade, is one way to stimulate buds. Then transfer the plant indoors, before night temperatures drop into the low 40's. Keep the plant in a room that is dark at night, no light from lamps or outdoor sources, for a few weeks and buds should form for mid-winter bloom.

You can force the plant to flower earlier by simulating lower sunlight earlier in the fall. In early September, cover the entire plant with a box or a black cloth at 6pm, for 12 to 14 hours each night, over a four-week period; buds should form, blooming in about six weeks. 

Propagation:

Kalanchoes propagate easily by 2" to 3" stem tip cuttings from fresh green stems, taken after flowering, in spring or summer. Harden off the cuttings for about a week and then use a rooting hormone on the ends before placing them into a moist, light, soil mix. Keep the plant warm, humid, and in indirect light while it forms roots. Do not handle the plant for 1 to 2 months. 

What to Watch for:

To encourage branching and produce the most growing tips capable of bearing flowers, prune and shape kalanchoe after flowering.

Plants become lanky in form and floppy if light is too low.

In order to re-bloom the plant for Christmas, give it an extended period of darkness for thirty days. Beginning September 1, cover the plant with a box or a black cloth from 6 pm to 7 am each night until October 1. Under these conditions, the plants will develop flower buds and be in bloom for the holiday season.

If re-blooming is not required for the winter holidays, kalanchoe will bloom in the midwinter to spring under normal houseplant growing conditions.