Editing Cactus (section)

===Light and temperature===

Although semi-desert cacti may be exposed to high light levels in the wild, they may still need some shading when subjected to the higher light levels and temperatures of a greenhouse in summer.{{sfnp|ps=none|Brown|2001|p=85}}{{sfnp|ps=none|Hewitt|1993|p=150}} Allowing the temperature to rise above {{convert|32|C|F}} is not recommended.{{sfnp|ps=none|Hewitt|1993|p=150}} The minimum winter temperature required depends very much on the species of cactus involved. For a mixed collection, a minimum temperature of between {{convert|5|C|F}} and {{convert|10|C|F}} is often suggested, except for cold-sensitive genera such as ''[[Melocactus]]'' and ''[[Discocactus]]''.{{sfnp|ps=none|Pilbeam|1987|p=11}}{{sfnp|ps=none|Innes|1995|p=22}} Some cacti, particularly those from the high [[Andes]], are fully frost-hardy when kept dry (e.g. ''[[Rebutia minuscula]]'' survives temperatures down to {{convert|−9|C|F}} in cultivation<ref name=Amos12/>) and may flower better when exposed to a period of cold.<ref name=Shea12/>