A column cactus is a large, thorny cactus with one or more upright, ribbed, columns. Its scientific classification has been changed several times and the correct scientific name is now Cereus hildmannianus, though some sources may still refer to it as Cereus uruguayanus or Cereus peruvianus. This species is a native of northern Argentina and the southeastern corner of Brazil. Other common names for the plant include apple cactus, organ pipe cactus and hedge cactus. The column cactus is fast growing and is often grown indoors.
There are five to nine prominent ribs running up the sides of most column cacti. Occasionally, plants are found with the ribs spiraling around the column rather than growing vertically. The ribs are rounded and the brown thorns, or spines, grow along the ribs. Column cacti are blue-green in color.
An average column cactus reaches a maximum height of 10 to 15 feet (about 3 to 4.5 m) in an outdoor setting, or 3 to 6 feet (about 1-2 m) when grown indoors. On a full-grown plant each column can be up to 14 inches(about 35.5 cm) in diameter. Some column cacti are branched, with two or more columns growing on the same plant. Those with multiple columns may have inspired the common name "hedge cactus," as the profusion of branches and thorns can make a very effective landscape barrier.
The flowers are trumpet-shaped and grow up to 6 inches (about 15 cm) long. They are most often white, though some have touches of color on the edges of the outer petals. Flowers on mature plants usually open at night and close before dawn.
Column cactus fruits are ovoid, with skins of varying shades of red to yellow, fading to green toward the ends. The interior is filled with creamy white, edible flesh. Tiny black seeds, also edible, are scattered throughout the flesh of the fruit.
The best locations for column cacti are usually in full sun on fast draining soil. This is an arid climate plant and normally requires a setting with low humidity to thrive. When grown indoors, a column cactus will usually do best in a warm, dry room where it gets plenty of sun. It is frequently recommended that all indoor cacti be watered only when the soil in the pot is mostly dry.
Column cacti have naturalized in several parts of the world including some arid portions of Hawaii and Puerto Rico. It is also found in northeastern Australia. The plant is classified as a noxious weed in Hawaii.