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.
Cannabis cultivation
Hydroponic systems greatly increase aeration of plant roots, and increase control of nutrient uptake. Hydroponic systems are decidedly more difficult to operate for the amateur or hobby grower, as over-fertilization is common, because there is no soil to act as a nutrient buffer. For this reason, many growers now use coconut fiber as a soil-less medium because of its high drainage and buffering capabilities that make it almost impossible to over-fertilize. Additionally, if a hydroponic system fails, the crop has a high probability of dying as the roots rapidly dry out (this is especially true of aeroponic systems).