Cleistocactus strausii
The cactus prefers free draining soils, strong sunlight, but not high temperatures — in fact it can withstand hard frosts down to -10 °C. In its natural habitat it receives plenty of water during the summer, but almost none over the winter. In cultivation, watering too much in winter often leads to root rot.
Cactus
Although in most cacti, the stem acts as the main organ for storing water, some cacti have in addition large taproots. These may be several times the length of the above-ground body in the case of species such as "Copiapoa atacamensis", which grows in one of the driest places in the world, the Atacama Desert in northern Chile.
Photosynthesis requires plants to take in carbon dioxide gas (). As they do so, they lose water through transpiration. Like other types of succulents, cacti reduce this water loss by the way in which they carry out photosynthesis. "Normal" leafy plants use the C mechanism: during daylight hours, is continually drawn out of the air present in spaces inside leaves and converted first into a compound containing three carbon atoms (3-phosphoglycerate) and then into products such as carbohydrates. The access of air to internal spaces within a plant is controlled by stomata, which are able to open and close. The need for a continuous supply of during photosynthesis means the stomata must be open, so water vapor is continuously being lost. Plants using the C mechanism lose as much as 97% of the water taken up through their roots in this way. A further problem is that as temperatures rise, the enzyme that captures starts to capture more and more oxygen instead, reducing the efficiency of photosynthesis by up to 25%.