http://www.orchidcare.com.au/media.html
Many different potting media have been used for cymbidiums-straight osmunda, fiber, rockwool, or fir bark, mixes of loam, dried oak leaves, and redwood fiber, or various combinations of standard horticultural materials. The important thing is to have a light, porous medium, capable of holding moisture but draining thoroughly. When plants need to be divided and repotted, do it in the spring after blooming. Repot only when the medium has broken down, for cymbidiums do best when not disturbed.
Household culture link
http://www.orchidspot.com/