Cephalocereus - Old Man Cactus
DESCRIPTION: This small group of cacti is native to Mexico. These slow-growing, columnar-shaped, blue-green plants can reach a height of up to 50 feet in the wild. However, in cultivation they rarely exceed a height of 3 feet. The spines of these cacti vary in length, but are sometimes long and silky. Trumpet-shaped, pink, white, or yellow flowers open at night on plants that are at least 20 years old. The blossoms are followed by seedpods that split open when ripe. C. senilis (Old Man Cactus) is one of the most popular cacti in cultivation. The long, woolly spines are thickest at the top, especially on very old plants. The older plants also produce cream to pink colored flowers and rosy seedpods.
POTTING: These cacti can be grown outdoors in mild climates where the temperatures remain above 40º F; otherwise, they may be grown in a home or greenhouse. The best potting compost consists of four parts sandy loam, and one part of equal quantities of sand and crushed brick. An addition of calcium to the soil would be beneficial. When their roots become cramped, they need to be repotted; this should be done in April. Cacti should be repotted every other year because the soil tends to go bad. That doesn’t necessarily mean that they will need larger pots. They need good drainage, about one quarter of their pot needs to be filled with crocks, covered with coarse leaves, and the soil must be made firm with a potting stick. After repotting, the soil should become almost dry before any water is given. When the plants are established, the soil is kept moist from April to October. If the silky spines become dirty, they can be washed and carefully combed.
PROPAGATION: Pieces of shoot or stem, taken from any part of the plants, will form roots. When cacti form offsets, they can carefully be removed after they've grown to a decent size, and potted. When cuttings are taken, they should be laid in the sun for a day or two to allow a corky skin to form over the cuts, which prevents rotting. Then they are inserted in pots of equal parts moist peat and sand, or in sand alone. The pots are placed on a bench or a shelf in the greenhouse or in a light window. Seeds may also be sown.
VARIETIES: C. chrysacanthus; C. hoppenstedtii; C. leuccephalus; C. nobilis; C. senilis
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