Cereus Cacti and Succulents
From the Latin cereus, wax-like, pliant, referring to the stems (Cactaceae). Torch cactus. Greenhouse succulent plants.
This genus has been split up into several genera, including Acanthocereus, Arthrocereus, Bergerocactus, Binghamia, Borzicactus, Brachycereus, Browningia, Camegia, Cephalocereus, Cleistocactus, Corryocactus, Dendro-cereus, Erdisia, Escontria, Espostoa, Eulychnia, Haageocereus, Harrisia, Heliocereus, Jasminocereus, Lemaireo-cereus, Leocereus, Leptocereus, Lophocereus, Machaerocereus, Monvillea, Myrtillocactus, Neoabbottia, Neoraimon-dia, Nyctocereus, Oreocereus, Pacyycereus, Peniocereus, Rathbunia, Stetsonia, Trichocereus, Wilcoxia, Zehntnerella.
The cereus have erect or sprawling stems, all with spines and all flowering at night. Theare mostly large and in many species are fragrant.
C. chalybaeus, up to 10 feet, in nature, stem columnar, a deep blue. 5-6 ribs, flowers red, white inside, Agentina. C. hexagonus, short-jointed, 6-angled stems, long white flowers, West Indies. C. horridus, 15-20 feet high in nature, stems branched, 4 ribs, flowers greenish-red, South America, C. peruvianas, 35 feet high in nature, a favourite in collections, ribs variable, 5-8, bluish-green to blue, straight spines, flowers brownish-green outside, white within, a form of monstrous growth is in cultivation, south east Brazil.
A suitable consists of compost with few added nutrients, with a sixth part of added coarse sand or grit; broken brick may be incorporated in this. Repot in March or April every two or three years or more frequently if the plant grows too large for the pot. Water from March to October but give none in winter; temperature, 65 °F (18°C) in summer, 40°F (4°C) in winter.
Propagation is by seed sown in a good seed compost in pans; cover the seeds lightly, keep moist and shaded at a temperature of 70 °F (21°C). Prick out the seedlings when the cotyledon has been absorbed. Seedlings grow fairly quickly and will need an annual repot. The branching types may be increased by taking sideshoots as cuttings. These must be dried at the cut so that a skin forms before they are put in to sharp sand and peat in equal parts. Do not push the cutting too far into the compost but support it with a stick if it is tall. The base should just rest on the rooting medium. Pot up into the usual compost when roots form.