Publication: J. S. African Bot. 41(2): 101. 1975
Origin and Habitat
Bushmanland and south-eastern Namibia.
Habitat: It grows on bare patches of sand.
Cultivation and Propagation
Crassula corallina subsp. macrorrhiza are quite smart for the extremely dry circumstances where these plants grow. But not so difficult to grow if you remember not to over-water in the Summer when they’re taking their rest. They can grow easily on window sills, verandas and in miniature succulent gardens where they are happy to share their habitat with other smaller succulent plants, or in outdoor rockeries. They are spring and autumn grower (summer dormant).
Soil: They prefer a very porous potting mix to increase drainage. A slightly acid or neutral soil is ideal. You can grow a plant in a 6-10 cm pot for years and have perfectly happy plants. For best results, use a shallow pot.
Watering: Winter grower, provide some water all year around, in the wild most of the growth occurs during spring and autumn- recommend water less in summer. During the winter months, water only when the soil becomes completely dry. Wet soil quickly causes root and stem rot, especially during chilly winter months, but can re-root if taken care of. No water should ever be allowed to stand around the roots. Low ambient humidity is always needed. Roots will rot in ever damp soil.
Fertilization: The plants are fertilized only once during the growing season with a balanced fertilizer diluted to ½ the recommended strength.
Sun Exposure: They need full sun or bright, filtered light with ample airflow to stay compact, generally needs full sun part of the day to bloom, but avoid direct blasting sun in mid summer (with sun exposure the leaf develops a nice reddish tint), they do not do well in full shade as they tend to etiolate, fall over and rot easily.
Pest & diseases: Crassulas are sensitive to mealybugs.
Rot: Rot is only a minor problem with Crassula if the plants are watered and “aired” correctly. If they are not, fungicides won’t help all that much. Care must be given in watering, keeping them warm and wet while growing, and cooler and dry when dormant.
Hardiness: Although the plants will survive mild frost if kept dry (hardy as low as -5° C) they should be protected from frost to prevent scarring. USDA 9b-12
Use: It is an excellent potted plant great for windowsill culture as well as in rock gardens. Indoors only in brightest position.
Pruning: Remove old leaves from plant base and dead flower spikes only.
Propagation: They are easily propagated by the removal of off shoots, remove a lateral shoot and insert the basal part buried in the soil. This shoot should root within a month, and small offshoots will form at the base. They can also be grown from seed or leaf cutttings.
Bibliography
Major references and further lectures
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Doreen Court “Succulent Flora of Southern Africa” CRC Press, 01/giu/2000
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John Wilkes “Encyclopaedia Londinensis” Volume 5 1810
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Vera Higgins “Crassulas in Cultivation.” 1964
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George Don “General History of the Dichlamydeous Plants” Vol.3 1834
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Gordon Rowley “Crassula: A Grower’s Guide” Cactus & Company, 2003
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Jacobsen “Lexicon of succulent plants” Littlehampton Book Services Ltd. 1974
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James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11/ago/2011
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Dr J.P. Roux “Flora of South Africa” 2003
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Domitilla Raimondo “Red list of South African plants 2009” South African National Biodiversity Institute, 2009
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Werner Rauh “The Wonderful World of Succulents: Cultivation and Description of Selected Succulent Plants Other Than Cacti” Smithsonian Institution Press, 1984