Copiapoa barquitensis is a distinctive Chilean cactus, slow-growing and recognized by its hemispherical shape and bronzed epidermis. Its compact nature and subtle coloration make it a sought-after specimen. Cultivating this species offers a rewarding experience.
Description and Natural Habitat
Copiapoa barquitensis typically exhibits a depressed-globose to columnar stem, 3-4 cm in diameter, reaching up to 7 cm in cultivation. Its skin color ranges from greenish-grey to bronzed, sometimes appearing disc-shaped and partially sunken in its natural setting. It features 10 to 14 spiraled ribs, divided into low tubercles, and a white woolly apex.
Older parts may lack spines, while younger sections can have thin, short radial spines, less than 4 mm long, initially brownish or black, turning ash grey before falling off. During summer, it produces scented, yellow or pink flowers, 1.5-2 cm long and 30-40 mm wide. These diurnal flowers open a few hours after sunrise and close before sunset.
This cactus originates from the arid coastal deserts of northern Chile, specifically the Atacama Desert near Chañaral, one of the driest places on Earth with negligible annual rainfall. It thrives in rocky, mineral-rich conditions, often deriving moisture from coastal fogs known as “camanchaca.” Its taproot helps it access deeper water sources and store moisture.
Cultivation and Care
Light
Copiapoa barquitensis requires abundant sunlight to maintain its compact form and prevent etiolation. While it thrives in full sun, extreme summer heat with direct sun can lead to scorching, especially if ventilation is poor. Good air circulation is important with intense light. Ideal placement offers bright, direct sunlight for most of the day, with potential for light shade during the hottest parts of the afternoon in hot climates.
Watering
Watering should be infrequent and carefully managed, as Copiapoa barquitensis is highly susceptible to rot from overwatering due to its taproot. The “soak and dry” method is recommended, allowing soil to dry completely between waterings. During its summer growing season, it requires light but regular watering, pausing if the plant appears plump to avoid cracking. Mature plants are prone to rot after transplanting, requiring extra caution with watering.
Soil and Potting
A well-draining, gritty, mineral-rich soil mix with low organic matter is crucial. An open, sandy-gritty cactus compost is suitable; some growers recommend a mix of 75% pumice and 25% organic material. The soil should facilitate rapid drainage to prevent waterlogging around the roots. Pots should have adequate drainage holes, and shallow pots are often preferred to accommodate the root structure while preventing excess moisture retention.
Temperature and Humidity
Copiapoa barquitensis is well-adapted to high temperatures and requires a dry atmosphere. It can tolerate significant heat, but poor ventilation in humid or cool conditions can lead to problems. The minimum winter temperature is 5°C (41°F); completely dry plants can endure light frost. Ideal growing temperatures range between 6°C and 30°C (43°F and 86°F).
Fertilization
Fertilization should be sparse, if applied, as these cacti thrive in poor soils and can develop excess vegetation susceptible to fungal diseases with too much nutrient input. If fertilizing, use a cactus-specific fertilizer high in potash and low in nitrogen, diluted to half strength, once during the growing season. Fertilizing in spring or early summer is generally sufficient.
Dormancy
Copiapoa barquitensis experiences winter dormancy. During this time, keep the plant dry, especially when night temperatures fall below 10°C (50°F). Reduced watering is essential; some growers keep them bone dry throughout the coldest months to prevent root rot. As temperatures rise in spring, a light watering can help wake the plant from dormancy, gradually increasing water as growth resumes.
Propagation
Propagation is primarily from seeds. Seeds can be sown in fine, well-drained sandy soil when temperatures are warm, typically in spring. After sowing, apply a fine layer of grit, and water the pot from below, potentially with a fungicide to prevent damping off. Covering pots with glass or clear plastic for one to two weeks helps maintain high humidity for germination. Once seedlings emerge, replace the cover with light shade-cloth, and gradually reduce misting as plants grow.
Common Problems
Overwatering is the most frequent cause of problems, leading to root rot, which can be fatal. Its taproot makes it sensitive to excessive moisture. Insufficient light can result in etiolation, where the plant stretches and loses its compact shape. Pests like mealybugs and spider mites can affect these cacti, though healthy plants in mineral potting mixes with good ventilation are generally pest-free. Scorch marks can also occur from too much direct sun, especially after winter dormancy.
Conservation
Copiapoa barquitensis is part of a genus facing conservation challenges. Over two-thirds of Copiapoa species are classified as Critically Endangered or Endangered by the IUCN Red List. Threats include habitat destruction from urban and industrial development, and illegal collection for the horticultural trade. The slow growth rate of these cacti, some living for hundreds of years, means poached plants represent an irreplaceable loss to wild populations. Responsible sourcing from reputable nurseries is important to avoid contributing to the illegal trade.