Leaves on my Ludisia discolor are turning red
Stefan says: Ludisia discolor, sometimes called the jewel orchid, is unusual among orchids in that the main attraction is the foliage, rather than the flowers, which are relatively small compared with, say, those of a phalaenopsis. It originates in the rain forests of south-east Asia and the foliage has an almost velvety dark green-purple appearance with paler stripes.
Red leaves, on almost all kinds of plant, indicate some form of stress. With ludisias, the most common form of stress is bright light. They naturally grow on the forest floor and require and tolerate dull conditions. This is one of their great merits as house plants. Other possible causes of stress are over-watering, a shortage of house plant fertiliser, a low temperature (it must be above about 15C/59F even at night), and, worst of all, a combination of these factors.