PlantFiles: Blue Columnar Cactus, Facheiro, Facheiro Azul, Mandacarú de Facho
Pilosocereus pachycladus

It is NOT hardy to 10f. If anything, It is more tropical than the common Cereus.

There are many columnar cacti that are blue, this one is a bluer one. The most 'common' names are "Facheiro, Facheiro Azul & Mandacarú de Facho".
This plant can reach from 7 up to about 30 feet or higher.
The subspecies 'pachycladus' has 5-12 high and broad ribs, Long central spines that can be distuinguished from radial spines. The areoles that bear flowers are extra hairy.
The subspecies 'pernambucoensis' has 13-19 lower thinner ribs, the radial & central spines are about the same length and not easily distinguishable from each other. The areoles that bear flowers are not very hairy.

Other synonyms are:Pilosocereus azureus, Pilosocereus oreus, Pilosocereus splendidus, Pilosocereus superbus, Pilosocereus schoebelii, Pilosocereus cyaneus, Pilosocereus cenepequei, Pseudopilocereus oreus, Pseudopilocereus splendidus & Pseudopilocereus superbus

according to recent literature, the proper name is now Pilosocereus pachycladus, and azureus is a synonym... and 10 years from now, it will go the other way again? By the way, this cactus grows way taller than 6' ... up to 30' in its native Brazil

By the way, it is not cold tolerant to the mid 20s as Botany Bob asserts (actually, Botany Bob was me in a previous account)... all my Pilosocereus froze when it got down to 25F, though only the tops (protect with styrofoam cups and/or wrap tops with newspaper next time!). Made all my perfect solitary columnar plants into branching plants... not as nice, but I have noticed all Pilosocereus in southern California are branching plants with cold scars on them, so I am not alone.

I am not going to say this is a water-loving cactus, but summer watering only seems to make it grow faster, and it is exceptionally tolerant of high water exposure, at least when hot... not had one rot in winter rains, either, but I don't dare water it even more just to tempt fate.

This is one of the most spectacular columnar cacti that can be grown in the warmer, drier areas of the US. It is the most amazing turquoise/ sky blue color. The spines are relatively small and protrude along ridges that run up the plant from top to bottom. As Pilosocereus cacti age, they produce what is called a 'pseudocephalium', where the plant produces thick, soft tufts of orange/white hair (sort-of like that seen in 'old man cacti). This area of the cactus is where the flowers pop out (a relatively rare occurence, at least here in Southern California).

The cold tolerance of this species isn't known, but it can tolerate frost, and some freezing down to the mid 20s briefly, without any harm. Water requirement is minimal, as with most cacti, though it appreciates watering in the warmest months. Most Pilosocereus are from Mexico or Brazil... no information on this one's origin, but suspect Brazil, where the more colorful species grow.

Pilosocereus are excellent pot culture cacti, and therefore can be grown in most areas of the country, if protected from heavy summer rains and winter freezes.