Cleistocactus STRAUSII

Cleistocactus STRAUSII - Silver Torch cactus, Straus's cleistocactus, Cleistocactus strausii.

Cleistocactus is a genus of South American cacti in the family Cactaceae, comprising about fifty species. They grow in the foothills of the Andes, on hilly and rocky areas of Bolivia, Argentina, Peru, and Uruguay, often at considerable altitudes above sea level. Recently, a number of previously independent genera were included in the genus.

The stems are columnar, erect, decumbent, or almost creeping depending on the species, ribbed, and branching from the base. The length of the stems ranges from 30 cm to 3 meters (1-10 ft) with a thickness of only a few centimeters. There are 7-30 radial spines, thin and straight, 0.3-1.5 cm (0.1-0.6 in) long, and 1-3 needle-like central spines, up to 5 cm (2 in) long. In a number of species, the areoles are so closely spaced and the ribs so close together that the spines completely conceal the stem surface.

The flowers are tubular, 2 to 9 cm (0.8-3.5 in) long, in shades of red, orange, or greenish, protruding almost horizontally from the stem. Their main feature is that they practically do not open, with only the pistil and stamens protruding outward. The fruits are small, globose, fleshy, with black seeds.

Cleistocactus strausii is a species native to Bolivia, where it grows on dry rocky slopes at altitudes from 1500 to 3000 meters (4900-9800 ft) above sea level. The stems are columnar, erect, gray-green, up to 3 meters (10 ft) high with a thickness of only about 6 cm (2.4 in), branching from the base and forming a dense clump.

There are 25-30 ribs, densely covered with areoles, from which emerge about 20 short white radial spines and 4 longer yellowish-brown central spines, up to 4 cm (1.6 in) long. The white pubescence is so dense that the stem appears frost-covered. Flowering begins on specimens taller than 45 cm (18 in) and occurs in late summer: dark red or burgundy tubular flowers up to 6 cm (2.4 in) long protrude from the stem almost at a right angle.

Cleistocactus seeds are small, black, and shiny, maturing in small fleshy fruits. Soaking such seeds is impractical, so the substrate itself is sanitized: before sowing, it is drenched with a weak solution of potassium permanganate and dried slightly. Scarification and stratification are not required.

Sowing is carried out on the surface over a moistened loose substrate with the addition of sand, without burying. The sowing is moistened from a spray bottle with a growth stimulant solution: SUPERthrive, HB-101, Aminozol, Epin, or Zircon, covered with film or placed in a greenhouse, and germinated in the light, but not in direct sun, at a temperature of 20-25 °C (68-77 °F) with daily airing.

Under favorable conditions, the first seedlings appear within 1-2 weeks; the main germination is usually completed within a month, while individual seeds may delay longer. Both waterlogging and drying out of the sowing are unacceptable. Pricking out is performed after the appearance of the first spines, into individual small pots.

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In summer, the cactus needs a sunny location, but not in the driest conditions - unlike desert species, Cleistocactus originates from mountain regions with more humid air.

In winter, the plant is kept in a bright, cool place; a temperature of about 10 °C (50 °F) is quite sufficient. An important feature: unlike most cacti, the stems of Cleistocactus should not shrivel in winter because they do not regain turgor, so the plant must not be allowed to dry out completely.

Watering depends on the season and the condition of the substrate: water only after the soil has completely dried out. In summer heat, drying occurs quickly, so watering must be done more frequently; in winter, watering is reduced to a minimum, but not stopped entirely.

The plant develops best in a nutritious substrate to which coarse sand is added to improve water permeability. The mixture can be prepared independently from turf loam, leaf soil, and peat soil with sand. Drainage is placed at the bottom of the pot.

Fertilizing is carried out during the period of intensive growth once a week with cactus fertilizer. In winter, fertilizers are not applied.

Young plants are repotted once a year in spring, adult plants only as needed when the roots no longer fit in the pot.