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.
Opuntioideae
Notably, their lack of collapsible cortical cells, ribs, and tubercles mean that they cannot absorb water or transfer it intercellularly as easily as the other cacti, so this may place evolutionary constraints on the aridity of habitats and maximum adult size. One adaptation around this problem is the evolution of flattened cladodes that allow opuntioids to swell up with water, increasing in volume without an increase in surface area risking water loss. Opuntioids also lack fiber caps to their phloem bundles, which in other cacti protect against sucking insects and stiffen developing internodes.