Overall, however, the temperatures given are only average values. For example, it is inevitable, that on hot summer days the temperature rises higher in spite of all efforts, which is also survived without damage by orchids that are kept cool or at a moderate temperature, if it is not a permanent condition. Likewise, warm house orchids will lower the temperature on cold winter nights +12 to + 15° C tolerated without damage, especially then, when there is little moisture. It becomes more dangerous for the plants, if an unfavorable temperature curve repeats itself frequently or the values suddenly become extremely contradictory.
When describing the genera and species, the temperature requirements are specifically mentioned. The plants are relatively adaptable; one did not, however, expect too much from them. Often they are kept too warm with well-intentioned intent. If this happens continuously over long periods of time, so the opposite is achieved; the plants get smaller instead of bigger. Plants in need of warmth do not develop properly if temperatures remain too low, even if all other growth factors are optimal. From the mentioned temperature ranges it can be seen, that the temperature should be lower at night. Too high night temperatures damage the plant; their functions should definitely be reduced at night.
Young plants are always kept a few degrees warmer, so that they develop quickly; but here, too, exaggerations are unsuitable.
When caring for orchids in inhabited rooms, the temperature will always be adjusted to human well-being within certain limits. It is subject to constant control, and emotional precautions are taken in good time, to avoid extreme extremes. The situation is different with free-standing greenhouses, especially then, when a sudden deterioration in the weather causes temperature drops. In such cases and during the transition periods, the installation of an electric heater has proven itself, which enables rapid temperature control. When controlled via a thermostat, personal maintenance is largely unnecessary.
1 Gongora galeata; 2 Dendrobium devonianum; 3 Odontoglossum rossii; 4 Oncidium concolor