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.
Cattleya rex
This species does not tolerate dryness for long periods, so watering must be done regularly and should be reduced in frequency during winter. However, the growing medium (cork slabs, baskets or pots) must have good drainage, so the roots can dry properly after watering or root rot may appear.