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.
Arrojadoa
Source :.
These tropical cacti are not very easy to grow. With their snake-like growth, they are ideal cactus for hanging baskets. They are growing relatively rapidly in good conditions. It multiplies more by seeds than by cuttings. It grows best on slightly humid soil and with plenty of watering from spring to autumn. In winter it should be left without water and at a minimal temperature of 10 °C.