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.

[Hedge]

Originally Posted by Ray

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.

I think in a pot, we supply an abundance of all life's requirements, where as in the wild soils may be poor or short of one nutrient and in the case of an epiphyte, the roots are processing air and rainwater to gain nutrients. I know that's not very scientific, but it holds for cacti too - pot up too big in too rich a compost and all you get is vegetative growth. Connie, where are you??