What, a 4 " diameter pot vs a 6"? How tall were the pots? Was the 6" pot deeper/taller??

Yes. An azalea type pot is shallower. So the 4" was shallower and smaller in diameter.

On a sort of side note, for the longest time I was somehow convinced that with pots, deeper was better. However, with my watering tendencies my media would always have a central core that just wouldn't dry out (until I cut numerous holes in the pots). Realizing this, I switched to using either baskets or the shallowest pot I could find. Since I've been doing this my plants have done considerably better (and they were fine before).

The issue isn't so much the pot size, but how the grower provides a plant's culture? An orchid can thrive in a large pot with fine media, as long as the grower is aware of the plant's requirements. I think the reason people are advised to use small pots because there is a tendency to water the entire pot, when the plant itself occupies a small portion of the pot. I made this mistake when I first started growing orchids. Like jkofferdahl stated, he adjusted by putting holes in his pots to allow for more air exchange.

I have adjusted my pots by using Rand Aircone pots for some top heavy plants. For my other orchids like Phalaenopsis and Neofinetia plants, I use pots that have large silts on the sides, and I put a net pot inside the root moss. For my Vanda, I eschew pots and media and just hang them on a single wire, bare root. I have started to also install Spanish moss on the roots to help maintain some humidity.

OK, thanks. Yeah, in that case the bad thing with the 6" pot wasn't that is was wider, but that it was deeper. Go deep with any medium other than large bark, and you would be 100% right that wider is worse.

However, had they been the same depth, I don't think you would have seen a difference.

---------- Post added at 01:10 PM ---------- Previous post was at 01:08 PM ----------

Yep. There it is. The roots themselves do NOT need to dry out, it's the medium that needs to dry out, because a constantly wet medium risks and accelerates low oxygen zones at the core.

---------- Post added at 01:16 PM ---------- Previous post was at 01:10 PM ----------

You are quite right. As long as you get the watering right you can grow most orchids in most media, however, once you start potting an epiphytic orchid, you are compromising its health. Maybe by only a tiny bit, but every compromise pushes it to the edge.

I use the Spanish moss on my vanda roots too, and it really seems to give good results.
Spray it every day with a proper low level fertiliser, and it will grow like crazy.
I bought two clumps, one ended up on my vanda, and the other was split up over a couple of mounts,and every time the clumps got too thick, I resplit it again and again so that now I have more spanish moss than I know what to do with.

Yep Dolly the 6" was way bigger. You probably would have been OK if it had been an Azalea 6" pot. I have been having trouble finding azalea pots any more around here.

Me too, Shannon.

One suggestion is, to 'cut and shut' two pots to make one very shallow one.
Here, I use a 30cm pot and a 25. I use the top of the 25 and the bottom of the 30, slide the bottomm into the top then when it is snug, I use a hot metal rod to make holes all round the pot on the midpoint of the joint.

bil... many people would not have the time to do that...Or the skill and inclination.

My guess is people do better with orchids in small pots for two reasons:

First, orchids in the wild don't grow in pots, nor in chips of bark from cold-winter trees. The "terrestrials" mostly grow in leaf litter on the ground, with roots very close to the air. Not many of us grow true terrestrials that prefer roots in real soil. The epiphytes have much more air circulation in habitat than they will ever get in a pot.

What matters here isn't that the pot is small, but how far the most deeply-buried roots are from the air. A wide, very shallow pot gives the equivalent aeration to a very small cubical pot. But, most people with cold winters want to fit as many pots into their winter growing area as possible, so we don't want wide pots.

Second, we humans have this uncontrollable need to stuff vastly excessive amounts food and drink into the mouths of ourselves and everything around us. As proof I offer all my friends' cats and dogs that are as wide as coffee tables, not to mention my friends themselves. So almost everybody overwaters by compulsion. The only cure for a lot of us is a job with long hours. A plant in a small pot will survive longer with regular excessive inundations than will a plant in a large pot.

It's the same with cacti. Cacti during their growing season actually prefer staying somewhat moist. But most people can't let anything get nearly dry, so they drown their cacti. Those able to restrain themselves find cacti do better with lots of root room and a wet period of 3-7 days after watering during warm weather.