Hi Barry, many people advocate immediate repotting of new plants to check things are OK at root level; depending on the nursery this may or may not be a good strategy. A quick look at the overall state of the medium, and possibly knocking the plants out of the pot quickly, should be enough to judge. If the medium looks like it's OK until the "right" time to repot that plant (new root/pseudobulb growth) leave them; if there is any doubt, replace the media/repot. Make sure the plant doesn't wobble when you're done.
Another deciding factor can be if you have a uniform potting medium in your collection that behaves differently from whatever they're potted in - it simplifies looking after many plants when the medium is mostly pretty similar in characteristics.
Generally, you want to repot when plants are in active growth, which for many orchids would make autumn a bad time.
Some people suggest soaking bark medium overnight and only use the bits that sink. I soak moss in R/O water prior to use; I don't like using it when dry. I usually mix in some perlite with the sphagnum.
Stanhopeas seem (in my limited experience) to quite like water; so long as the sphag isn't continuously sopping wet, they should enjoy it (my 3 are in bark in baskets though).
Hope this helps...
|