When you have the right pot and potting medium, here's how to proceed.
If you're using new bark, soak it overnight then rinse and drain.
Use a pot that just fits the current roots. Too large a pot will retain too much water, which can lead to rot.
Take the orchid out of its current pot. Soak the whole plant--roots, leaves, soil, everything--in a pan of water for an hour or two. This makes the roots more flexible, so you'll have less damage with the repotting.
After the soak, carefully remove all the old potting mix from the roots. Pick and rinse it off, until all you have are leaves and roots, no old mix at all.
Healthy roots are plump and green. BUT--very important--don't start cutting off other roots! Only remove old roots that are clearly rotting--brown or black, soft and mushy. Roots with breaks, brown or black spots, and parts of the outer velamen missing are still OK! Don't cut them off! Old roots that are brown and dry are still OK. Don't cut them off! Roots are the key to a healthy plant. Be careful with them and keep as many as possible.
Put the now-bare plant in the new pot, and start filling in with bark. I find a chopstick very helpful for positioning the bark around the roots. The base of the lowest leaves should end up just above the bark. The crown of the plant should be mostly upright. (It's normal for them to gradually lean over, that's OK.) Don't pack the bark, just loosely fill it in under and around the roots. These roots need air!
Don't water for a day or two. Keep in mind that new bark holds very little water, so water often--two or three times a week for the first year. Water runs right through, so keep an eye on the plant and don't be afraid to water a lot.
Keep it warm and in moderate light--no direct sun. It probably won't bloom until next fall, when temps are cooler and days shorter.
Use very dilute fertilizer, follow label directions. "Weakly, weekly" works for me. Don't try to force growth or blooming. Aim for a healthy plant, with gradual growth. Sometimes they'll only add 2 leaves a year.
Bark breaks down over time, plan on re-potting every 2-3 years, or when the bark starts looking like compost.
There are different ways of doing all this, but the above process and materials have worked well for me. My first orchid is now ten years old, and blooms every year. They're great houseplants, and not that hard once you learn what they like.
Questions or Comments? Please speak up!
Happy Growing
