Most orchids need bright, indirect light, humidity, gentle air circulation, thorough watering once or twice a week, fertilizer during growth periods, and daytime temperatures of 65 to 75 degrees Fahrenheit with only small temperature drops at night. Orchids require good drainage and should not be allowed to sit in water.
Monitor orchids' health by observing the leaves. Healthy plants have thick, bright green leaves that are not wrinkled. Dark green leaves indicate insufficient light, while reddish leaves, fading leaves or leaves with black splotches can indicate too much light. Cattleyas, dendrobiums and oncidiums usually prefer brighter light, and they do best near windows facing south or west. However, miltonias, phalaenopsis and paphiopedilums need lower light intensities, and they do better near windows facing north or east.
Wrinkled leaves indicate too little water, which can result from underwatering or overwatering that has damaged the roots. Check the growth medium, which should be moist but not soggy. Misting the plant is acceptable, but do not allow water to stand on the leaves. Repot the plant and replace the growth medium at least once every two years, but not when the plant is in bloom.
Fertilize the plants with a fertilizer made for orchids according to the instructions on the label. Fertilizing too little can result in stunted growth and lack of flowers, while too much fertilizer may burn the roots and leaves.