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.
Disocactus flagelliformis
Rattail cacti are very easy to grow, being suitable for a greenhouse and container, indoors or out. These plants need a minimum temperature of 6 °C (43 °F). They should be grown in bright, indirect light, in a fairly rich potting mix. The best compost consists of four parts sandy loam, and one part of equal quantities of sand and crushed brick. They should be repotted every other year because their soil tends to sour. This doesn't mean, however, that they'll need larger pots. Once the plants are established, keep the compost moist from April to October; less water is required from November until March, just enough to keep the stems from dying back. In the winter, old or discolored stems may be cut out at the base to encourage new growth.