REPOTTING

Orchid roots often creep over the edge of the pot before the body of the plant makes it to the edge of the pot. This is not necessarily an indication that you need to repot the plant. Repotting is only necessary when the body of the plant has grown over the pot edge or the media itself breaks down and will no longer allow the roots to dry between waterings. Under ideal growing conditions (and if you didn't overpot the plant to begin with), most commonly cultivated orchids outgrow their pot before the media breaks down.

The best time to repot is at the beginning of the growing season. This gives the plant the best chance to grow into the new pot and secure itself.

Follow these basic steps to repot your orchid:

Assemble all your supplies:
Cutting tool(s)
Plant(s) to be repotted
New pot (select the next size up... don't overpot!)
New media
Sterilize your cutting tool (an open flame passed along the blade for a few seconds is ideal). You should resterilize the tool between each plant you cut. At OrchidMania we also use latex gloves and change them with some degree of frequency, especially after handling a plant with an insect infestation or other problem.
Gently ease the plant out of its old pot. Don't be afraid to destroy the old pot if it will help keep the roots of the plant intact.
Gently remove as much of the old media as will come off the roots.
Remove any bad (overly dried or soggy brown) roots.
Put drainage material and a little media in the bottom of the pot.
Place the plant in the pot. The rhizome or crown should be slightly below the rim of the pot.
Sprinkle new media into the pot, allowing it to work down among the roots of the plant. Push it in gently, but do not force the media in and do not compact the media. You want an airy mix that allows good circulation. Do not bury the plant's rhizome or crown.
If necessary, stake the plant to steady it.
Water lightly until the plant adjusts to its new pot.

sources:orchids.org
photo courtesy of aka fortex