Cereus (seer-ee-uhs) Many cacti found themselves in the genus Cereus before being moved out into different genera. The result is a catch all genus with striking variability and fantastic forms made up of the ones who remain.
Form: Typically tree like, branching and most similar to the stereotypical desert cactus you see in cartoons.
Colors: Mostly green but many have tinges of blue involved as well. The spines can be anywhere from yellow to black or silver.
Foliage: Made up exclusively of spines.
Flowers: Typically large and snow white. Many only bloom at night and smell very floral. Most have smooth stalks but some are lightly scaled.
Light: These prefer full sunlight, the more, the better.
Soil: Pick a gritty, well-draining mix like a cactus and succulent soil (available at garden centers) or mix your own (more info).
Water: Water deeply enough for water to run out the container’s drainage hole. Allow soil to completely dry before watering again. Keep dry in winter.
Hardiness:Cereus are not frost hardy and should be brought indoors to a sunny window sill if there is a chance of frost. (What’s my zone?)
Propagation: Most can be rooted from stem cuttings however, all of them can be produced via seed.
NOTES FROM THE NURSERY
Cereus is one of the oldest genera of cacti, with the first usage of the name being in 1625. It use to apply to all tall growing cacti but has lost many of its members to other genera as time has gone on. Many other genera have the word "cereus" in their names as an homage to this genus.
What remains as Cereus are those that cannot be moved into the other genera. As such, Cereus is defined less by a set of traits and more by not being defined as anything else. This leads to strong variability that you don't find in other genera but also means that, as taxonomy advances, it's very likely more and more plants will be transferred out of Cereus and into other genera.
Cereus repandus f. monstrosus - Peruvian Apple Cactus [large]