What is wrong with a too big pot?

[jasonmom]

I don't understand why a pot can be too big . Can someone tell me why?

Thanks

[lotis146]

Hi Jasonmom!

I'm a newbie here and amateur Orchidist (?) but I wanted to offer up what little bit I learned yesterday from a YouTube video about this subject. It was useful to me so even as inexperienced I am (and the suffering I've caused my Orchids) this may help you.

In this video I watched by "soo neaty", she'd potted a Phal. keiki (baby orchid that forms from a node on the mother plant) in a "too big pot". She came back to this choice after the keiki hadn't grown at all since being potted, thus removed from the mother plant. She said that Orchids need a smaller pot for their roots than we'd think because they like to feel secure. In the wild they cling/attach to trees and hang off of them, the security of the tree enabling them to support their spikes and flowers. Thus I get that she was saying a smaller pot that holds the roots somewhat snug gives the plant security in knowing it can hold up its spike.

Perhaps this is wishful or childish thinking, I'm sure the experts will correct me if need be but I hope this helps if I'm right!

I know I've always wanted to repot them in bigger pots to encourage growth as you would with other houseplants. (They told me not to repot bigger with an African Violet but I did anyways and it's quadrupled in size but hasn't flowered, which is not a surprise as it's focused on growing.) But I've come to accept what they say that Orchid pot size is dependent on the size of the root ball, NOT the size of the plant above ground. The roots are the determining factor, the ah ha moment for me! Oh and I have repotted at least my mini Phal. too big and I think it's suffering in part from this.

Take care,
Lotis

[quiltergal]

It really has more to do with how evenly the media dries from the outside to the center of the pot. If the pot is too big in relation to the size of the root system the center of the pot will never really dry out. So while the media on the top may feel dry the center is still very wet. This eventually leads to root rot as the media in the center breaks down and compacts from being constantly wet. The compaction of the media around the roots causes them to suffocate and die which then leads to rot.

Ideally the root system should just fit snugly in the pot.

[MattWoelfsen]

Big pots bury roots too deep and do not allow air to circulate throughout the root ball. This can cause moisture retention which would lead to root rot. For my plants in 4" pots and larger, I place an inverted net pot in the center to provide a hollow space, then I drape the roots around this pot and fill with potting media. If I do not have a spare net pot to bury in the media, I get plastic hollow hair curlers from places like Dollar General, cover the top, so that media don't fill the curler. I also use pots with slots on the side to allow more air flow.

Overtime, I have realized that epiphytic orchids don't need pots to grow, so the smaller the pot the better.

[Ray]

Terri & Matt both "nailed it". The reason relates to the potting medium.

I'll use a phalaenopsis grown in S/H culture as the example of "it can be done": I pot my phals in pots having a diameter as close as I can get to the total leaf span of the plant - it's not uncommon for me to take plants from 3" pots and put them into 8.5" ones.

The reason that works is because the LECA wicks the water so well, that it stays quite uniform throughout the pot (with a small gradient from bottom to top, as that's where the evaporation occurs), its near-spherical shape keeps it open and airy throughout, and it will never decompose.

As an aside, every phal I do that will puts its aerial roots down into the medium, farther from the plant base, and no longer produces more.

[NYCorchidman]

They know where to go to drink instead of wandering around in the dry air. lol

[jasonmom]

Originally Posted by Ray

Terri & Matt both "nailed it". The reason relates to the potting medium.

I'll use a phalaenopsis grown in S/H culture as the example of "it can be done": I pot my phals in pots having a diameter as close as I can get to the total leaf span of the plant - it's not uncommon for me to take plants from 3" pots and put them into 8.5" ones.

The reason that works is because the LECA wicks the water so well, that it stays quite uniform throughout the pot (with a small gradient from bottom to top, as that's where the evaporation occurs), its near-spherical shape keeps it open and airy throughout, and it will never decompose.

As an aside, every phal I do that will puts its aerial roots down into the medium, farther from the plant base, and no longer produces more.

What is S/H and LECA? Also, I don't understand what is being said in the last sentence. Should I try to put the aerial roots into the media?

My plan is to put some packing worms in the middle and then surround with Miracle Grow orchid bark (it's big pieces) and mix in a bit of moss. What ya think?

Thanks

[MattWoelfsen]

S/H = semi-hydro, and LECA stands for Lightweight Expanded Clay Aggregate. It is clay fired at a fairly high temperature, and is known by a variety of names....Hydro-ton and Primeagra being two you hear frequently on the Orchid forum.

Phalaenopsis grow air roots seeking moisture. Under optimal growing conditions, plants will seek the closest source of moisture. LECA and s/h produce such an environment. I would convert to this media but I'm too set in my own growing ways to make such a change.

When you repot your plant you might want to gently place the roots in the new media.

[lotis146]

Thank you for the correction and all the useful information, so helpful to an amateur such as myself. It's good to know the reasoning so if you do decide to go bigger you can account for what you know.

I think in the future I will order some LECA and use next time I repot.

[Leafmite]

The entire purpose of the medium is to keep the air humid around the roots. You want the medium to dry evenly and at a fast pace so that you can water the roots but not keep the medium around them wet...just ever so slightly damp so that the air around the roots is humid. Wet medium will rot the roots.
The plastic curlers and net pot provide an air space that helps keep the medium drying evenly as more of it is exposed to air. I use net/basket pots to grow most of my orchids which works the same way. LECA, being clay, stays slightly damp but not wet.
As said, many orchids do grow clinging to trees or rocks, or have their roots in the leaf-litter layer, in a nice, humid environment. We try to create this environment with what tools we have available to us.