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.
Puya dasylirioides
Puya dasylirioides comes from 2300-3300 meter elevation, where the climate is cool all year. It has taken temperatures in the mid-80s (30 °C), but it's possible that it won't thrive in consistently warmer conditions, especially if nights are warm. It is said to have taken winter lows of 19 °F (-7 °C), and might even handle colder temperatures. It grows well in a deep pot in normal cactus soil that contains no lime. Water it deeply occasionally, and avoid letting the soil dry out completely. Some protection from strong afternoon sun might be needed in warmer climates. Over about 40% humidity is recommended.