Many people advise repotting orchids you’ve gotten right away. These growers fall into two camps:
1) Experienced growers who actually know what they’re talking about, but don’t realize they have plenty of newbies in their audience
2) People who don’t know what they’re talking about
Obviously, ignore (2) whenever possible. For a few tips on how to detect these well-meaning but dangerous-to-your-orchids people, see this post: Questions To Ask About Any Orchid Advice You’re Given [coming soon].
Now when an experienced grower gives you advice, they’re telling you what works for them, because they already know how orchids fare in their own growing conditions AND (this next part is very important) they know what to expect.
When an experienced grower repots their plants immediately, they’re doing it because they have a media/growing mix they prefer BECAUSE they understand how their media performs with water retention and their watering frequency. Just as importantly, they also know how long it will take for newly-acquired plants to respond (e.g., grow new roots) and hence have the proper expectations. These experienced guys tell you what they know works for them, but they don’t always keep in mind that new growers lack the experience to place this advice in the proper context.
New orchid growers have usually grown other houseplants, and generally repotting a houseplant soon after you get it is the right move. What these new orchid growers don’t know is how slow orchids root and grow relative to houseplants. They (and even some experienced growers) also don’t know that orchids make roots adapted to the media they’re growing in. Switching from, say, a coconut husk medium over to sphagnum moss may be exactly the right thing to do for long-term health of a plant, but the newbie grower is usually expecting something to happen fast, like in a few days. After all, this is what happens with other house and garden plants, right? Unfortunately, for orchids: wrong. New roots might take weeks, or even several months to start to grow. It depends on the type of plant, the media, the humidity level, etc.
If you’re just getting into orchids, DO NOT REPOT your plants right away. You want to give your plants time to adjust to their new home — the light, the temperature, the humidity (hopefully high), the water quality, and watering frequency. Re-potting right away compounds the stress faced by your plants after they’ve arrived. In fact, re-potting into a new, DIFFERENT media than your plant was growing in can be quite stressful for some orchids. If the media is good stuff, and the growing conditions are good, the plant will be just fine in the long run (do expect a few dropped leaves). If you’re new to orchids, the conditions you’re providing newly-arrived plants may not be great yet; that’s to be expected because, after all, you’re still learning. But you can lighten the load on your new plants by not repotting for six months or even longer. A healthy plant will NOT be harmed by not repotting. (If the plant is not healthy, repotting is one of the best things to do, but hopefully as a new grower you’re not trying to recover stressed orchids; that’s something you do when you’re an advanced grower.)
Not repotting your new orchid right away will give you a few months to see how it does in your growing conditions, and hopefully give you time to get more educated about the types of media out there, and how to create great growing conditions for your orchids. And most importantly, it gives you the time to acquire the proper expectations for orchids. They’re NOT garden/vegetable/typical house plants, and they do things on their own time scale. Repotting into new potting media, and expecting a fast and obvious response from the plant, is absolutely the wrong expectation to have and will lead to frustration for the grower and stress for the plant…or even worse if the grower falls into the orchid newbie vicious cycle of errors.