Pilosocereus pachycladus subsp. pachycladus - Blue Torch Cactus

The Pilosocereus pachycladus subsp. pachyclladus, still sold under the synonym Pilosocereus azureus, is the Brazilian blue cactus, also called the blue torch cactus. It is characterised by erect stems of a mineral powdery blue, adorned with wooly areoles and golden blonde spines. This houseplant naturally finds its place in contemporary décors and cacti collections. It thrives indoors in a very bright location or in a frost-free conservatory.

Belonging to the Cactaceae family, this columnar cactus is native to eastern Brazil, from Bahia to northern Minas Gerais. It is found in dry environments marked by alternating seasons, particularly in the caatinga and other open formations of the dry tropical biotic region. In nature, it eventually forms a large ramified specimen that can reach several metres in height. In a pot, it shows much more moderate growth and most often reaches 30 to 50 cm in height and 15 to 40 cm in width at maturity. Its growth is slow to moderate. Its cylindrical stems, which branch as they age, bear 5 to 19 ribs well defined. The epidermis, blue-green to pale blue, is covered with a slight bloom that accentuates its bluish colour. Its white to yellowish areoles bear fine bristles and spines initially golden yellow, becoming greyish with age. On adult specimens, in good conditions, white nocturnal flowers can appear in summer, more or less washed with red or green on the outside, measuring 4 to 7.5 cm long. When fruits form, they are purplish red and contain a magenta pulp. Its spines mean it should be placed away from thoroughfares and out of reach of young children.

Indoors, it requires very bright light, a few hours of direct sunlight, a dry to slightly humid atmosphere, around 30 to 50% humidity, and temperatures between 18 and 30 °C, without dropping below 10 °C for extended periods. It is a plant accessible to beginners, but it does not tolerate insufficiently sunny rooms and stagnant humidity.
Place it near a south- or west-facing window, in a bright conservatory, or in a well-glazed office.

The blue torch cactus can spend the summer outdoors, provided it is gradually acclimatised to direct sunlight, placed sheltered from excessive rain, and brought back indoors as soon as night temperatures drop below 10 to 12 °C. It enjoys heat, requires a very well-draining substrate, and is only watered when the mix is dry deep down.

You can place it among other cacti such as the blue candle cactus Myrtillocactus geometrizans, the cactus spurge Euphorbia trigona ‘Rubra’, the Senecio mandraliscae and the Cleistocactus strausii. Their slender silhouettes and bluish or purplish