It depends upon what type of orchid it is. Your particular zone often has nothing to do with it. Unless the type of orchid you want to repot happens to be a terrestrial type, these would be suitable to grow in some type of soil based mix.
Most orchids we grow like Phalaenopsis, Cattleyas and Dendrobiums are epiphytes. Epiphytes grow on something for support like a tree branch and can not survive potted up in soil. Why? Because air must be allowed to circulate around their roots at all times.
Within the "Orchid Forums" here on this site, we have numerous thread or 'stickies' that deal with questions and answers such as yours. You could read through the sticky on growing "Supermarket Orchids-Phalaenopsis", if this is the type that you have. I personally started a thread on how to repot a Cattleya type orchid or Bulbophyllums. But the method depends somewhat on what type of orchid it is.
THE KEY IS- NO SOIL.
There are several people here who can offer you their opinions on how to best grow certain orchids. Look at the label with the plant for a name or send us a good image of the plant so that we might assist you further. BigBill
Welcome to the Orchid Forums!!!!
Phalaenopsis once potted up properly can be grown outside in Zone 9 but they require shade, no direct sunshine. They like temperatures from 65-85. They need to be watered before they go bone dry. They like good air movement and a little plant food 3 or 4 times a year.
