Cymbidium orchids should be repotted once every two years to provide them with fresh planting medium. They should be repotted and transplanted to a larger pot when the roots and pseudo bulbs are growing up and out of the pot. Choose a new pot that is 2 to 3 inches larger in diameter than the last but no larger as cymbidiums like to be slightly root bound and will bloom best when slightly compressed.
Lean the cymbidium pot on its side and slide or pull the plant from the pot. Brush off all of the old planting medium that is tangled in and stuck to the roots.
Fill the pot one-quarter full with a coarse orchid planting medium designed for epiphytic orchids. Make sure it contains some combination of bark chips, coarse-chunk horticultural charcoal, perlite, sphagnum moss or coarse peat moss and does not contain soil.
Set the orchid into the pot adding or subtracting planting medium from below the root mass to make the top of the root ball sit just an inch below the lip of the pot.
Add potting medium slowly using your hands and a wood dowel to gently push the medium down into the orchid's roots until the pot is filled and the plant sits stable and upright.
Drench the planting medium and orchid roots under a faucet flowing with tepid water. Allow all of the excess water to drain away before placing the cymbidium back in its usual growing location.