New pot - Is it too big?

[Ray]

Originally Posted by Hedge

Many orchids will not flower unless their roots are quite confined...

Can someone explain a scientific basis for that? I have heard that a lot, have experienced it too, but an orchid growing on a tree has its roots spread out, unconfined, for literally meters and meters. The same is true of plants on mounts - they're certainly not confined.

You think perhaps it's a matter of stability ("grabbing hold" of the pot), rather than "confinement"? That's my only guess at this point.

Concerning S/H pot size and phals, I recommend taking the opposite approach and typically put them in pots as big as their leaf spread. I have found that when I do that, any aerial roots that were wandering outside of the smaller pot tend to sink themselves into the medium, which I interpret as another stability thing - think of them as "guy wires" stabilizing the rather top-heavy foliage on a relatively small base.

Jennyfleur is on the right track with media based upon organic components: As most of the evaporation from a pot is from the top (plastic) or top and sidewalls (clay), and stuff like bark does not wick liquids well, piece-to-piece, you end up with a soppy center "core" (inside the root mass) that can suffocate the roots, and certainly decomposes more rapidly, becoming dense, exacerbating the problem. Due to the relatively fast-wicking nature of most brands of LECA, coupled with the fact that it will never decompose of become compact, that is simply not an issue in a semi-hydro pot.