Myrtillocactus geometrizans - Blue candle cactus

Myrtillocactus geometrizans, nicknamed blue candle, is a species of cactus native to Mexico, recognisable by its upright, ribbed and branching stems, covered in blue bloom and armed with black thorns. In spring and summer, it produces small, white to cream flowers followed by small edible purple-blue fruits, called "cactus blueberries", with a sweet and slightly tangy flavour. Apart from its frost-sensitive character, blue candle is an easy and rewarding variety that will delight cactus collectors.

Myrtillocactus geometrizans belongs to the Cactaceae family. Native to the arid and semi-arid regions of central and northern Mexico, particularly in the states of Querétaro, Hidalgo, Puebla and San Luis Potosí, it grows in rocky and desert landscapes where it adapts to extreme drought conditions. It can reach 4 to 5 m in height in its natural habitat, but remains more modest in pots, where it grows more slowly. Its cylindrical and thick stems measure on average 6 to 10 cm in diameter and display a very decorative powdery blue-green hue. They are marked with well-defined midribs, usually numbering 5 to 7, on which small white areoles develop, bearing short brownish to blackish thorns. Flowering of Myrtillocactus geometrizans occurs on mature specimens, reaching about 60 cm in height, which can take several years. Growing conditions must be optimal to encourage flowering: full sun exposure, at least five hours of direct light per day, and a winter rest at temperatures of 10-12°C in a dry substrate. The cup-shaped flowers are white to cream and appear in spring or summer. Pollination is carried out by insects outdoors. This cactus produces fleshy and edible fruits, called "cactus blueberries", measuring 1 to 2 cm in diameter. They take on a purplish hue when ripe and are appreciated for their sweet and slightly tangy flavour. Hardy down to -2°C in dry soil, it is preferable to grow it in pots in cold regions to bring it indoors in winter.

Blue Candle enjoys a sunny exposure, essential for the intensity of its bluish hue and its good development. It is undemanding, tolerates drought and only requires moderate watering in summer, with spaced-out watering in winter, when it enters dormancy. It will go with Mangaves, Echinocactus grusonii and Aloe striatula, which highlight its slender habit and bluish hue. In pots, it can be paired with other cacti such as Cereus peruvianus or Cactus Euphorbias.