Cleistocactus strausii
As a houseplant, the Silver Torch cactus is an easy to take care of so long as over-watering is avoided. To naturally simulate the porous effects of the sand in its native habitat, it's important to ensure that excess water will not pool in the soil, causing the roots to become water logged.
This plant’s native habitat does not have winter, but when temperatures drop to the low twenties, it can exhibit signs of tip frost. 
The Silver Torch cactus is most susceptible to 
mealybugs 
and spider mite.
Cactus
Many cacti have roots that spread out widely, but only penetrate a short distance into the soil. In one case, a young saguaro only tall had a root system with a diameter of , but no more than deep. Cacti can also form new roots quickly when rain falls after a drought. The concentration of salts in the root cells of cacti is relatively high. All these adaptations enable cacti to absorb water rapidly during periods of brief or light rainfall. Thus, "Ferocactus cylindraceus" reportedly can take up a significant amount of water within 12 hours of as little as of rainfall, becoming fully hydrated in a few days.