Cereus forbesii Spiralis

Cereus forbesii 'Spiralis' is a magnificent plant, forming an imposing candelabra with spiral-shaped stems, very curious looking. This species forms a bushy shrub with a tree-like habit that can reach up to 4m (13ft) in height, with upright stems that branch strongly from the base, ranging from deep green to bluish-green in colour. Its few ribs are very deep and spiral to the right and left, sometimes changing direction during growth. In summer it bears abundant nocturnal flowers, white and very nectar-rich, measuring 15cm (6in) in diameter, which only close in the late morning. Very floriferous, fast-growing and highly drought-resistant, it is a visually striking plant perfectly suited for rockeries in hotter regions, or for cultivation in large pots indoors or in a conservatory or greenhouse, in colder regions.

Cereus forbesii 'Spiralis' is a natural mutation of the type species, discovered in 1992 by the Argentine botanist Omar Ferrari. Cereus forbesii belongs to the vast family of Cactaceae. It is a plant that withstands drought and heat well and tolerates temperatures as low as -2°C (28.4°F), especially if the soil is perfectly drained and dry. Cultivate it in a pot, in full sun, in a well-draining substrate, preferably sandy, composed of equal parts of potting soil, sand and garden soil. Young plants prefer shaded, non-scorching exposures. Outdoor cultivation in regions with mild winters can be done against a well positioned wall or in a dry rockery.

Cereus forbesii 'Spiralis' is a very attractive cactus due to its spiral-shaped ribs and prolific flowering. Because of its particularly rapid growth and imposing size, it requires large containers and regular repotting. They are upright to bushy succulent perennials that tend to produce numerous shoots at their base. They reach about 3m (10ft) in all directions. Each stem is erect, 10 to 12cm (4 to 5in) in diameter, with a dark green epidermis covered with a bloom that sometimes gives it a bluish hue. They have 5 to 9 deep and distinct ribs, which spiral to the right or left, a tendency that can change during growth. The ribs have sparsely hairy areoles with short, stiff and not very numerous spines. Plants over 4-5 years old flower from July to September, offering surprisingly large funnel-shaped flowers, 15 to 25cm (6 to 10in) in diameter, white with light brown sepals.

In hotter and dryer regions, Cereus forbesii 'Spiralis' will find its place in a dry and sunny rockery or on a wild slope. Elsewhere it can be planted in a pot, to be stored away when the first frosts arrive and not watered until vegetation resumes in spring. It can be combined with other cacti such as echinocactus, ferocactus, astrophytum, and mammillaries to create miniature desert gardens, or it can be placed alone in a pot to decorate a windowsill or a corner of a conservatory.