One important growth factor is room temperature as well as the temperature during the year which is especially important for orchids with a rest period. Often a (significant) fall in temperature together with water reduction will initiate the flowering period.
According to their need for heat, orchids can be differentiated into 3 Groups:
– hot house orchids which like day temperatures of about 20 to 25 degrees
The most common one is Phalaenopsis (moth orchid) but some Lady´s Slippers (you will recognise them by their marbled leafes) and Dendrobium (for example Dendrobium phalaenopsis) like it warm.
– orchids for tempered glass house which like day temperatures of about 15 to 20 degrees
These are often lady´s slippers (often they have green leaves) and many Dendrobium, Oncidien and Cattleya.
– orchids for cold glass house which like day temperatures of about 10 to 15 degrees
Often these plants are Odontoglossum, Coelogyne or other Dendrobium (as for example the well known Dendrobium nobile) and most of Masdevallia. They like it rather cool and humid (humidity).
Night temperatures for all three groups of orchids should fall by 2 to 3 degrees (nocturnal fall).
We can not always say that all plants of one kind prefer the same temperatures. If you cultivate natural kinds of orchids, it is very important to know your plants´ demands. Most (but not all) of the commercially traded hybrids can be cultivated in temperated or warm environnements we are comfortable in.