Cleistocactus strausii
Silver Torch cactus can thrive in low-nitrogen soil without facing the consequences of low nitrogen. Too much water will make the plant weak and lead to root rot. 
Least Concern. This cactus is locally abundant in its native land and has few local threats to its survival.
This cactus can be propagated by cuttings or seed.
Cactus
All cacti have some adaptations to promote efficient water use. Most cacti—opuntias and cactoids—specialize in surviving in hot and dry environments (i.e. they are xerophytes), but the first ancestors of modern cacti were already adapted to periods of intermittent drought. A small number of cactus species in the tribes Hylocereeae and Rhipsalideae have become adapted to life as climbers or epiphytes, often in tropical forests, where water conservation is less important.