Astrophytum ornatum - Bishop's cap

Astrophytum ornatum, also known as the star cactus, is a columnar cactus prized for its geometric habit and star-shaped patterns. Its body features prominent ribs covered with fine white tufts, giving it a certain elegance. At maturity, it produces large, bright yellow flowers at its apex. It is easy to grow in a pot with a well-draining substrate, in a sunny position, with spaced-out watering. You can place it on the terrace during the warmer months.

Astrophytum ornatum belongs to the Cactaceae family and is also known by the names Echinocactus ornatus, Astrophytum glabrescens, Astrophytum ornatum var. mirbelii. It grows naturally on the rocky and arid slopes of the central plateau of Mexico. It can reach up to 1 m in height in the ground, but its growth is slow. Indoors, it remains more compact, typically measuring 30 to 60 cm in height at maturity. Its body is marked by well-defined ribs, adorned with small white woolly tufts, which form star-shaped patterns. These structures help the plant to reflect light and limit evaporation, an adaptation mechanism to desert conditions. Its robust, yellowish to brownish thorns become less prominent with age. In summer, when it reaches maturity, after 7 to 10 years and under optimal conditions, it can produce large pale yellow flowers, measuring up to 7 cm in diameter. These flowers are very beautiful but short-lived and open during the day. They can appear successively for several weeks.

Indoors, the star cactus requires a very bright position, with several hours of direct sunlight per day. It tolerates high temperatures but must be protected from the cold: it suffers when temperatures drop below 5 °C. Its growing substrate must be very well-draining, composed of a mix of cactus compost, coarse sand, and perlite, to avoid excess moisture. Watering should be moderate, allowing the soil to dry out completely between waterings. In winter, the plant enters a dormant period, and watering should be almost stopped. Overwatering can lead to root rot, the main cause of failure in cultivation. This cactus is resistant to diseases but may be attacked by mealybugs.

Astrophytum ornatum has rigid thorns that can be dangerous if handled carelessly. It is advisable to place it out of reach of children and pets to avoid any risk of injury.

With its slow growth, Astrophytum ornatum is perfectly suited to pot cultivation, in a bright living room, conservatory, or greenhouse. A terracotta pot will optimise drainage while being less suffocating for the roots. It pairs well with other columnar cacti, such as Echinopsis terscheckii, as well as with compact succulents like Lithops or Echeveria agavoides. Its majestic appearance also allows it to be grown alone, as a centrepiece in a cactus collection.