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.
Houseplant care
Since almost all of the air circulation (transpiration) happens in the roots as does almost all of the energy production, the roots must be able to breathe easily. Overwatering will drown a typical houseplant. The air is pulled through the soil by the breathing of the roots. Air must be able to flow through the soil.