Orchids vary in their temperature preferences
Ruffly-flowered Cattleya hybrids, often referred to as corsage orchids, are among the easiest orchids to grow indoors.
Photo/Illustration: Alex Vasiljev
Temperature affects an orchid’s overall growth and especially its bloom habits. The most critical time for orchids is during the winter, when many of them are preparing to bloom. Orchids are classified into three types based on their winter temperature needs: cool-, intermediate-, and warm-growing.
Cool-growing orchids enjoy night temperatures in winter around 50°F and daytime temperatures not exceeding 70°. Intermediate-growing orchids prefer minimum winter-night temperature around 60° and daytime temperatures from 70° to 85°. Most orchids best suited for growing indoors are in the intermediate group (see sidebar). Night temperatures for warm-growing orchids should not be lower than 65°, and daytime winter temperatures can range from 75° to 85°. During the summer, intermediate- and warm-growing orchids can stand temperatures up to 85° or 90° as long as they have good air circulation. Cool-growing orchids prefer to stay cool in the summer.
A fluctuation of 10 to 20 degrees between day and night temperatures is essential for all orchids and triggers them to produce flowers. This difference is most important for cool- and intermediate-growing orchids because of the conditions they are used to in the wild. In the winter, it’s possible to achieve this fluctuation by lowering your home’s thermostat or by moving an orchid to a cooler spot, like a porch or a garage, at night.
Most orchids flourish under bright, indirect light. Full eastern or western exposure or indirect southern exposure usually provides enough light. However, as with temperature, specific orchids may require a certain light intensity. When buying an orchid, check the label for its light preference, then observe how much light your orchid actually receives.
Symptoms of excessive light are sun burn, yellowish foliage, and a plant that looks weak and dehydrated. On the other hand, if you bought an orchid in bloom and it did not rebloom the following year, even though the foliage looks green and full, consider giving it more light. Also make sure the temperature range is correct.