Kalanchoe
Kalanchoe is a large Old World genus of succulents in the stonecrop family Crassulaceae, grown by hobbyists for their showy flower clusters, felted or glossy foliage, and — in several species — the remarkable habit of sprouting ready-made baby plants along the leaf margins. The genus includes everything from the ubiquitous florist's Kalanchoe blossfeldiana on garden-centre shelves to bizarre tree-like giants and fuzzy "panda plant" collectors' pieces. Species once split off into the genus Bryophyllum — the plantlet-formers — are today usually folded back into Kalanchoe.
Description
Kalanchoe are perennial succulents ranging from small clumping herbs to substantial shrubs and even soft-wooded small trees. The leaves are the genus's signature feature and vary enormously: some are smooth and glossy, others thickly coated in silvery or brownish felt (a covering of fine hairs that reduces water loss and scatters strong sun), and many are toothed, scalloped, or curiously folded. Leaf arrangement is typically opposite, with each pair set at right angles to the last.
Flowers are borne in branched clusters held above the foliage, each bloom a small four-parted tube that flares into four lobes. Colours span red, orange, yellow, pink, and white, and a healthy flowering head can stay colourful for weeks — the main reason K. blossfeldiana is sold as a seasonal pot plant. Flowering is often triggered by shortening day length, which is why these plants tend to bloom naturally in winter and early spring.
A number of species (the old Bryophyllum group) produce tiny plantlets — complete with miniature leaves and roots — in the notches along their leaf edges. These drop off and root wherever they land, which makes the plants effortless to propagate and, in mild climates, genuinely weedy.
Distribution and habitat
The genus is centred on Madagascar and mainland Africa, with additional species reaching into the Arabian Peninsula and tropical Asia. Madagascar in particular is a hotspot of diversity and home to many of the most distinctive species. In the wild they occupy rocky slopes, thin soils, and seasonally dry scrub, where their water-storing leaves and drought tolerance let them ride out long dry spells. Several species have naturalised well beyond their native range and are considered invasive in warm regions, spread largely by their dropped plantlets.
Notable species
- Kalanchoe blossfeldiana — the florist's kalanchoe; compact, glossy-leaved, and sold in bloom in every colour.
- Kalanchoe tomentosa — the "panda plant," prized for silvery, brown-tipped felted leaves.
- Kalanchoe daigremontiana — "mother of thousands," lined with plantlets along every leaf edge.
- Kalanchoe delagoensis — "chandelier plant" (formerly Bryophyllum tubiflorum), with tubular leaves tipped in plantlets.
- Kalanchoe luciae — "flapjacks" or "paddle plant," with rounded leaves that blush red in bright light.
- Kalanchoe beharensis — "felt bush," a large species with big, wavy, velvety leaves.
- Kalanchoe pinnata — "cathedral bells" or "air plant," an old-fashioned windowsill curiosity that roots from a single leaf.
Cultivation
As a group Kalanchoe are among the most forgiving succulents, which is much of their appeal to beginners. Give them bright light — a sunny windowsill or lightly shaded outdoor spot — for compact growth and good leaf colour; too little light leaves them stretched, pale, and reluctant to flower. Grow them in a free-draining mix and water only once the soil has dried, easing off in winter. Most are frost-tender and should be kept above freezing, though they tolerate ordinary indoor warmth happily.
The felted-leaved species, such as K. tomentosa and K. beharensis, dislike water sitting on their fuzzy foliage, so water at the roots and give them good airflow. To rebloom the florist's kalanchoe, plants need a stretch of long, uninterrupted nights (short days) to set flower buds. See Watering and Repotting for general technique.
Propagation
Propagation could hardly be easier. The plantlet-forming species raise themselves — simply press the fallen babies onto damp soil, or let them do it for you. Other species root readily from leaf or stem cuttings left to callus for a day or two before potting. Clumping types can also be divided at repotting time, and species can be raised from seed, though few hobbyists bother when cuttings are so quick. See Propagation — cuttings and Propagation — offsets for details.
Cultivar and hobby notes
Florist's kalanchoe (K. blossfeldiana) has been bred into an enormous range of named colour and double-flowered strains, most sold simply by bloom colour rather than cultivar name. Among foliage species, growers seek out well-marked or variegated forms of K. tomentosa and the strongly blushing selections of K. luciae. The plantlet-formers are best treated with a little caution: they are gift plants that keep on giving, self-sowing everywhere, and in frost-free gardens they can become a nuisance — worth potting deliberately rather than planting out.
A note of caution for pet owners: Kalanchoe contain bufadienolide compounds that are toxic to cats, dogs, and livestock if eaten. They are best kept out of reach of curious pets. See Pests and diseases for the mealybugs and occasional aphids that are the main growing troubles.
See also
- Kalanchoe blossfeldiana · Kalanchoe tomentosa · Kalanchoe daigremontiana
- Crassulaceae — the stonecrop family
- Soil and potting mix · Watering · Propagation — cuttings · Propagation — offsets · Pests and diseases