Astrophytum SENILE, Viesca

Astrophytum SENILE, Viesca - Astrophytum senile, Star cactus.

Astrophytum is a genus of succulent plants in the Cactaceae family, comprising 6 species and numerous cultivars and forms growing on rocky and limestone soils in the foothills and mountains of northeastern Mexico and Texas.

Members of the genus are known for solitary, globose or cylindrical, ribbed stems and an almost complete absence of spines, although some species do possess several curved needles. The surface can be smooth or covered with white flecks forming unusual, light, felt-like, marbled patterns on the stem surface that are capable of absorbing moisture. Leaves are absent; the body of the plant is green, often with a glaucous bloom, adorned with areoles bearing spines.

The cacti grow very slowly, but bloom early with large, funnel-shaped, yellow flowers, sometimes with a red center, located at the apex of the stem. The flowers usually wither after a couple of days. With proper care, blooming continues for an extended period, from spring until late autumn. Fleshy, pubescent fruits with thin skin contain black or brown seeds.

Under modern classification, Astrophytum senile is not considered an independent species, but rather a fleckless variety of Astrophytum CAPRICORNE. It should be noted that in juvenile stages it possesses flecks, which it loses later. The stem is green, globose, becoming cylindrical with age, devoid of lateral shoots. In nature it reaches 35 cm (14 in) in height and 15 cm (5.9 in) in diameter.

Before planting, seeds are soaked for 3-6 hours in warm water with the addition of stimulants (SUPERthrive, HB-101, Aminozol, Epin, or Zircon), after which they are disinfected for 10 minutes in a weak solution of potassium permanganate, then air-dried and surface-sown onto a moist substrate consisting of leaf mold, river sand, and finely crushed charcoal in a 1:1:1 ratio. Moisten with a spray bottle, cover with film or place in a mini-greenhouse, and germinate in light, but not direct sun, at a temperature of 20-25 °C (68-77 °F), preferably with nighttime temperature reduction to 15-18 °C (59-64 °F). Regular ventilation is provided and uniform moisture is maintained.

Seedlings appear within 10-30 days, depending on temperature and humidity. The maximum germination period can exceed 45 days. Caution must be exercised with watering so as not to ruin the sprouts. Pricking out is carried out upon the emergence of 2-3 true tubercles, after which the plants are transplanted into individual containers. The seedlings, somewhat larger than those of other globose cacti at this stage, develop slowly but steadily. Blooming occurs at 4-6 years of age if the dormancy regime and good lighting are observed.

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The plant is placed in a sunny location, preferably on a south or southwest window. Access to fresh air and the absence of stagnant moisture are provided. The summer temperature is maintained at 22-30 °C (72-86 °F). In autumn, the plant is prepared for dormancy, and by winter the temperature is gradually lowered to 10-12 °C (50-54 °F) with complete rest.

Watering is carried out moderately after the substrate dries out, thoroughly soaking the root ball with water. In the winter period, watering is excluded. With the onset of the growing season, the ambient temperature is gradually raised above 12 °C (54 °F); at temperatures below this, the plant is incapable of absorbing water. The first watering is performed cautiously with a small amount of water.

A stable and shallow pot with a mandatory drainage layer is selected for cultivation. A mineral substrate with the addition of sand, gravel, and crushed brick is used. Repotting is carried out in spring, carefully avoiding damage to the root system, as new roots regrow with difficulty. The Astrophytum is potted on into a container barely larger than the previous one, just enough to fit it. Repotting is done from dry soil into dry soil, and watering is carried out after 5-7 days so that damaged rootlets dry out. Mature plants, starting from 10 years of age, are repotted rarely, at intervals of 5-6 years, and only if roots encircle the entire root ball.

During the growing season, once every 4 weeks, the plants are fed with specialized cactus fertilizers low in nitrogen, in diluted concentration. Fertilizers are not applied during the dormancy period. The plants poorly tolerate high calcium content in the soil. Shaping is not required. Propagation is carried out by seeds. Offsets are not produced.