I need to re-pot one of my orchids in the spring, too....I've never re-potted before, do you automatically go up a pot size or ? How do you know whether to go up a size or not?
And regarding the soil, I see bark recommended a lot. What kind of bark? Thanks!
The bark is generally sterilized fir bark and is typically marketed as "orchid bark" or "orchid mix."
When choosing your pot size, use the smallest pot possible. Once you have checked roots and trimmed the dead ones, you can usually get it back in the same pot, unless its been years since you repotted.
I use potting medium from RePotme.com, where you can order an already created mix or ask them to create a mix for you based on the various materials they have.
If the roots don't easily fit back into the container, then I use the next size up. That being said, sometimes I tinker with mine to get the roots back into the container a bit, but if they are just too big or too many of them then I pot in a size up.
The pot should just accommodate the roots and a bit more. In most cases, after grooming the plant, the plant can go right back into it's original pot, and if groomed hard, even down one size.