One of the hereditary traits of every plant is its attachment to a certain temperature range, which is fixed within certain limits. If these boundaries are moved arbitrarily or unintentionally, growth stops; drastic changes can lead to the death of the plant. Precise knowledge of optimal values is important, to ensure a favorable development. The dependence of the temperature on light and moisture is very great and we have to make an effort, to bring the ratio of these three factors to one another to the correct denominator. There is always a danger to the plants, if one of the factors mentioned shows very high or very low values, to which the others are not attuned. So high temperatures and strong exposure to light are unsuitable, when there is not enough moisture. High humidity at too low temperatures or other extreme contrasts are also dangerous.
The temperature measurement is one of the most important maintenance measures. It is not a matter of indifference, where the thermometer hangs. Even within a relatively small space, the temperatures are differentiated depending on the altitude, what to consider. The opinion, that tropical orchids must necessarily be cared for at high temperatures, is unfortunately widespread. It often leads to failure, which can be avoided at all costs, if the conditions of the home location are approximately taken into account. Depending on the type, the required temperatures vary within wide limits. But the values are also different within the seasons, likewise between day and night. When it comes to care, we distinguish between three large groups: cold, tempered, warm. Cold house orchids require around +16 to during the day in summer + 21 °C, at night about + 13 ° C; in winter during the day +13 up to + 16 ° C, descending at night until + 10°C. Many cymbidiums belong to this group, Odontoglossum, part of the Paphiopedilum species, Zygopetalum u. a. To be kept at a moderate temperature are u. a. Cattleya, Laelia, Oncidium, Stanhopea, many dendrobium, especially those from mainland Asia. The daytime temperatures should be around + 18 to + 24° C and +16 up to + 18 ° C at night in summer, in winter during the day +16 to +21 ° C and + 13 up to + 16 ° C at night. Orchids that need very warmth need constant temperatures at all times, approximately +21 up to + 29 ° C during the day and +18 to +21 ° C at night. This is true for Phalaenopsis as well as some Paphiopedilum- and Dendrobium species.
1 Cymbidium lowianum; 2 Cymbidium ‘Babylon Castle Hill’X C. ‘Alexanderi Westonbirt’; 3 Renanthera ‘Brookie Chandler’; 4 Aerides odoratum