Friday, April 20, 2012

Cephalocereus Senilis

With long white hair that completely covers the plant, the Cephalocereus Senilis – known as Old Man Cactus - is one of the most popular and identifiable members of the cactus group. But don’t be fooled by the attractive, silky-looking, woolly appearance; there are sharp yellow spines underneath all that shaggy hair that can inflict a painful wound, so be careful when handling this plant.

The Old Man Cactus is native to Mexico in areas such as Guanajuato and Hidalgo located in the east. The fine white hairs cover the entire fleshy, columnar body and hide the sharp spines. Aside from its charm, the hair serves an important purpose; it protects against the harsh desert sun, which is common to this plant’s native home. While researching information about this fascinating plant, I also discovered that its native habitat, Mexico, includes over five hundred species from the Cactus family and possesses the highest number of endemic and endangered cacti of any other country in the world.

I can’t stress enough how important it is to grow a Cephalocereus Senilis, which is highly-prone to rot from over-watering, in a well-draining, highly-porous soil mix. All succulent-type plants can easily turn to mush from excess moisture, but the C. Senilis seems more susceptible to it than many other cacti. During the active growing season, water thoroughly and then do not water again until the soil is completely dry. During the dormant period – late fall to early spring – keep almost completely dry; water enough to keep the plant from shriveling. Some resources of information suggest that this plant does not need to be watered at all throughout the entire winter. Although this is possible, it’s not mandatory; it all depends on the growing environment of your plant. If your plant begins to shrivel, give it some water. If it looks plump and content, don’t. It’s better to err on the side of under-watering.

Place this cactus in the sunniest spot available, especially during the winter when the quality and quantity of light is reduced considerably by shorter, cloudier days. Ample sunshine keeps this unique cactus healthy but it also encourages hair growth, which is what makes this plant so appealing. Very young specimens may need to be protected from midday sun.

Humidity is not critical; the Cephalocereus Senilis prefers a drier environment. Keep the plant warm (18°C - 29°C / 65°F - 85°F) when it is actively growing, and (if possible) provide cooler temperatures (13°C - 16°C / 55°F - 60°F) during dormancy. The plant should not be exposed to temperatures below 10°C (50°F) for extended periods.

In the wild, this plant can grow as tall as 40 – 45 feet. When grown indoors, although it can (but does not often) grow as tall as 10 feet, it usually only reaches heights of 12 – 18 inches. But don’t hold your breath for any significant growth spurts; this is a very slow growing cactus. Proper care, which includes a lot of sunshine, will encourage speedier growth but don’t plan on a large specimen any time soon. With its small root system and slow growth, repotting may not be necessary for quite some time. Older specimens produce white or rose-coloured flowers, but seldom indoors.

As the plant ages, the hair surrounding it gets dirty, and although I’ve never personally tried it, a few books and websites suggest cleaning it with a mild soap solution to retain the white colour. Cover the top of the soil to avoid drenching it, apply the soap solution to the hair with a soft brush (a toothbrush is ideal) and then rinse well with water.

Growing This Cactus In Hydroculture

Despite the fact that it’s a cactus, Cephalocereus Senilis is one of the best performers in hydroculture. Transplant with great care; grip the plant with tongs or wrap several layers of newspaper around it, lift it out of its pot, rinse the roots under running water and repot in clay pellets. The plant adapts readily to the hydro system with no ill effects. Water roots may take several weeks, even months, to emerge. Make sure the water level is always kept below the roots; let it dry completely before adding more water. You can allow the plant to stay dry for longer periods; if the plant shrivels, add water.

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