TEMPERATURE

Most in-home temperatures are acceptable for growing the most common types of orchids. Cattleya, Phalaenopsis, Paphiopedilum, Oncidium, Miltonia, etc. can all be grown with great success under normal home temperatures. In general, if it feels comfortable to you, these plants will feel fine, too. Diurnal temperatures between 65ºF and 80ºF are usually best, with noctural temperatures between 55ºF and 75ºF. Some plants, such as Phalaenopsis, actually require a period of marked difference between daytime and nighttime temperatures in order to initiate blooming; so if your home is utterly climate controlled and the temperature never fluctuates from day to night, you can actually have trouble blooming some kinds of orchids.

Most orchids are tough enough to grow outside their "ideal" temperature range. If for some reason you need to "stretch" an orchid's tolerance zone, one way to do so is by reducing the watering. This is particularly true for warmer-growing orchids forced to spend a little time under cooler conditions... they'll usually weather the cool period OK, as long as they aren't wet and cold. For cooler-growing orchids forced to endure hot weather, the key is lots of additional water and lots of good air movement. A cool grower exposed to hot temperature will bake in stagnant air, but would be fine under the same conditions if there is a fan blowing across the foliage (don't forget that increased air movement means increased transpiration... so adjust the watering schedule accordingly).

sources:orchidmania.com
photo courtesy of aka fortex