Crassula Dillenius (1732)
Latin: crassus = thick.
Crassula is a genus of around 200 species of succulent plants, ranging in size from less than an inch in height to 6 foot shrubs. They are distributed throughout the world, although the majority are from South Africa. Many attractive dwarf plants are available to the collector. Some of these are monocarpic and die after flowering, just as the plant achieves perfection.
The best known Crassula is probably C. ovata (Jade Plant) (synonyms: Crassula argentea, Crassula portulaca, Crassula obliqua ) which can grow into a large shrub or bonsai and tolerates a certain amount of neglect on office window ledges. It flowers during the winter months if kept just frost-free.
C. ovata c.v. "Hummel's Sunset" is a Jade Plant cultivar with brightly coloured red, yellow and green leaves. C. ovata c.v. "Gollum" is a cultivar with nearly tubular leaves. C. ovata c.v. "Hobbit" has somewhat flatter curled leaves.
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Large Crassulas on a South African hillside. |
Numerous attractive hybrids have been created. One of the most popular is C. mesembryanthemoides x C. falcata "Morgan's Beauty." Crassula "Buddha's Temple" is a hybrid Crassula falcata x Crassula pyramidalis.
C. helmsii (Australian Swamp Stonecrop) is a hardy aquatic invasive species that has become a major nuisance in inland waterways in England and elsewhere. Small 1 cm pieces will rapidly grow and infest any slow-moving water.
Cultivation: While Crassulaceae will generally tolerate a wide range of light levels, the compact growth and leaf colouration seen in their habitat requires high light levels, preferably direct sunlight. Jade plants and other tender species enjoy a sunny position on the patio during the summer. As with other succulents a gritty potting medium is suitable and overwatering encourages roots and lower stems to rot. If this happens, the stem should be cut back to healthy tissue, dried off for a couple of weeks and replanted in a dryish free-draining potting mixture. Many species will re-root.
In frost-free Mediterranean climates, many Crassulas are suitable for the garden. There are few truly hardy Crassulas suitable for the UK garden and similar climates with cold-wet winters. C. sarcocaulis is a hardy sub-shrub with a profusion of small pink flowers during the summer. It requires a sunny position and well drained soil. It can also be treated as a bonsai and pruned to make a very nice specimen up to 12 inches tall. A white-flowered form (C. sarcocaulis alba) is available.
The main pests are root and stem mealy bugs. Crassulaceae were generally intolerant of many older insecticides, especially Malathion. I have seen no adverse reaction from watering with systemic insecticides based on Imidacloprid e.g. Provado Vine Weevil Killer. This will protect against many insect pests. Prophylactic treatment is advisable if plants grown outside during the summer are brought indoors.
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Crassula Gallery |
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Crassula arborescens
N. of Worcester RSA |
Crassula brevifolia
RBG Kew |
Crassula capitella ssp. thyrsiflora
Knersvlakte |
Crassula deceptor
Knersvlakte |
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Crassula deceptor
van Rhyns Pass |
Crassula muscosa
Knersvlakte |
Crassula perfoliata var. falcata
Karoo Botanic Garden RSA |
Crassula orbicularis(?)
N. or Robertson RSA |
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| Crassula ovata / portulaca RBG Kew |
Crassula rupestris
Karoo Botanic Garden RSA |
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Families of Succulent Plants 
