Pot size--the smaller the better? Myth or fact.

[pedidiva]

I have learned a great deal from the boards. I have recently learned that the pots that i had my orchids in were too big, so i am repotting into smaller size pots.

My question is--which orchids do not like to be in a pot were the roots are "contained". In other words, are there orchids that enjoy being in a larger size pot? If so, please advise.

Thanks~~
Pedi

[King_of_orchid_growing:)]

In general...

Terrestrial orchids. Even then, not much bigger.

[pedidiva]

Thanks.

[Ray]

I believe there are two aspects to the pot-size discussion:

One is the the need of a plant to be "pot bound". Dendrobiums are notorious for that, although I really cannot "wrap my head around" the need, as in nature, they are not "bound" by anything. I do know that some of it is simply stability in the pot - smaller pots need fewer and/or shorter roots to be able to "grab hold".

The second aspect is one of drying of the medium.

In a smaller pot, the surface-to-volume ratio is smaller, so the entire mass of medium dries faster. In a larger pot, you are often left with a soppy center, which decomposes faster than the rest of the medium, potentially taking much of the root system with it.

I have noticed, however, that this is NOT the case with semi-hydroponics, as the moisture in the medium "communicates" well throughout the mass, so remains more-or-less constant, and does not decompose. LECA even dries more uniformly in traditional culture.

I have taken to putting phalaenopsis into S/H containers nearly as big as their leaf spans, and they love it.

[King_of_orchid_growing:)]

Phals love SH because that's as close in principle as how they actually grow in the wild.

They grow on moist trees or rocks (depending on the species) in humid forests. The bark on the tree is wicking up moisture from the rain, the ground, the fog or mist, and the humidity, but not retaining too much of it to stay soggy. I've not seen a single pic of a Phal on a dry tree.




Not quite sure what the deal with Dendrobiums are either, but I'll side with Ray's answer. The thing with Dendrobiums is that they like a lot of air around the roots. I've hardly ever seen them on trees covered in moss. The trees they're on are not as wet as those that Phals are on. In fact, many of the pics I've seen show them on trees that are fairly bone dry. Of course the humidity is what is causing lichens to grow on the trees despite the dryness.



Some terrestrial orchids grow on a bedrock with some organic debris covering their roots.

Occasionally some species of terrestrials grow in all organic matter such as Calopogon tuberosus.

Then there's the whole thing where terrestrial orchids in general don't put out as much roots as epiphytes do. Some terrestrial orchids put out tons of roots. Many do not.

This is what accounts for the whole potting issue with certain terrestrial orchids.

[RosieC]

Originally Posted by Ray

I believe there are two aspects to the pot-size discussion:

One is the the need of a plant to be "pot bound". Dendrobiums are notorious for that, although I really cannot "wrap my head around" the need, as in nature, they are not "bound" by anything. I do know that some of it is simply stability in the pot - smaller pots need fewer and/or shorter roots to be able to "grab hold".

The second aspect is one of drying of the medium.

In a smaller pot, the surface-to-volume ratio is smaller, so the entire mass of medium dries faster. In a larger pot, you are often left with a soppy center, which decomposes faster than the rest of the medium, potentially taking much of the root system with it.

I have noticed, however, that this is NOT the case with semi-hydroponics, as the moisture in the medium "communicates" well throughout the mass, so remains more-or-less constant, and does not decompose. LECA even dries more uniformly in traditional culture.

I have taken to putting phalaenopsis into S/H containers nearly as big as their leaf spans, and they love it.

Ray's said it all really, just what I was thinking as I opened the thread.

I also agree with Philip that it seems to be the terestrials that don't need it.

[johnblagg]

I always thought along the same line as Ray ....they are not restricted in any way growing on a tree in the wild so the only issue is really how fast medium dries not how much space is in the pot.

[pedidiva]

great discussion, Thankyou

[RobS]

The smaller the better is true but there is one limitation that a lot of orchids don't like repotting. So it should be small but big enough to allow 3 years of growing (at least for Cattleya alliance plants). But this depends on the species and is somewhere a matter of experience.

[beanluc]

Originally Posted by RobS

it should be small but big enough to allow 3 years of growing

To me, this is the main thing. You can ask the question another way: Do I want it to bloom again ASAP, or am I willing to possibly wait at least a year for the plant to fill the pot before blooming again?

Personally, I pick pots sized so that by the time the plant is established enough to want to bloom again, it has grown well into its new pot and has lots of new growth for spikes to come off. It's a trade off, but for me it seems that a small potting-up yields a poorer bloom next season.

2 out of 3 years of great blooms vs. 3 out of 3 years of so-so ones?

I agree with Rob: this is very general, and the details depend greatly on the type of orchid and on your own experience. I have some orchids which I *never* pot up, but instead only replace spent medium and return to same pot.