Pot selection for large, rootless orchid

[tuandatn]

Hi all,

This is a general question, but sometimes when I buy bareroot (or manage to damage roots myself...), I end up with a fairly large division, with only a few healthy roots from the front bulbs after all has been pruned. For example, perhaps there is a 6 or 7in long rhizome, but only the front few pbulbs have roots, that would fit easily in, say, a 2in pot. The issue I find is that if I size for the plant (rhizome) size, then the pot is woefully oversized for the root system, and I worry about stability and root rot. If I size for the roots, stability is still a concern, more than half the rhizome is outside the pot!

I have considered inert media (I like growing in LECA, not necessarily s/h). Also considered just having part of the rhizome hang off the side of the pot. Finally, division seems like a reasonable way to go about having a smaller front division that is closer in proportion to the root system, and a completely rootless back division that might be saved, but the loss of back bulbs seems like an additional stress to the repotting.

Would appreciate any advice from others who have had success with this particular challenge.

Thanks all!

TD

[Ray]

There are a lot of confounding issues there that need to be unwrapped.

By itself, a large pot does not lead to root rot.

If you have a large plant with no roots, in my opinion:

1) It should still go into a pot appropriate for its size.

2) That pot should be filled with a potting medium that is appropriate for a healthy plant of that size in your growing conditions.

3) You should find a way to mechanically stabilize the plant so that newly-emerging roots are not damaged by any “wiggling”.

4) You may want to take some extra actions to enhance the recovery, such as “tents” to trap humidity, rooting heat mats, Kelpak treatment, etc., but I think the right thing to do is set it up to meet the plant’s’ needs, once recovered, as that provides the least overall stress.

[Roberta]

First, what type of orchid are we talking about?
But in general, I see this as a 2-stage process. Older, rootless pseudobulbs (with or without leaves) that are firm, provide reserves for the plant while it is growing new roots. So while it is recovering, you don't want to be doing any "surgery"). Pot it in the smallest pot that you can manage, to accommodate the new growth (at least a year's worth) And as Ray noted, make sure that the plant is held firmly in place (stakes, rhizome clips, etc) so that it does not wobble. After a year or two, when you have some growths with good roots, you can repot (ONLY when it is just starting a new batch of roots) and at that time you can remove some of those back bulbs so that it fits in the pot better. At that point, since it has some good roots, it doesn't need those "reserves" so much. But don't be too aggressive... You should have 3-5 pseudobulbs in a division, less than that and you'll have a weak plant.

[tuandatn]

Thank you, both, for your replies!

Ray, that makes a lot of sense. One issue I find is that oftentimes, if there are a few good roots, they will be situated towards one side of the plant. So, when repotting, the good roots will be toward the edge of the pot. I find that as I wait for the media in the middle of the pot to dry out, the roots at the edges of the pot will have been dry for quite some time. This leads to a second question: in your experience, how long can a root system remain dry before there is irreversible damage from dehydration? Sometimes I worry because the roots at the edge of the pot start to look desiccated, but when I check the media in the middle, it's still wet, so I hesitate to water.

Roberta, I should have clarified, but mostly sympodials--laelias/cattleyas in particular. I'm certainly guilty of doing some surgery to remove unsightly old pseubulbs when repotting... I'll try to refrain. I usually try to make sure at least 3 good pseudobulbs are in the division, but I have had two recent scares that left me with single pseudobulbs to grow from...they seem not to be declining at the moment (and even putting out new roots!) but I'm afraid it will be a long recovery for both

[Optimist]

Ray has a lot of good points. I have usually gone back to what would the plant do in nature (without a pot). But, the stability issue-- until the plant has a good amount of roots is important. I have seen "A pot within a pot" and also the pot filled with heavier rocks for purposes of both drainage and "using up excess space" in the pot. So a pot with several large rocks in it is both a heavy pot and also a pot where the "space" is reduced. So if you have a 6-inch pot, but need a 3-inch pot, then fill 1/2 of the pot with big rocks (lava for instance) and suddenly the 6-inch pot is now a 3-inch pot. (This is also good for a weird-shaped plant that does not want to fit into the correct size pot. Hope that is legible.

[Orchid Whisperer]

If the plant is something like a Cattleya, sometime I find that hanging the plant in open air (outdoors, in shade, in summer, for a few months) causes the plant to send out a bunch of roots, even if it has few or poor roots at the start. If you can try that, you might have more roots to work with when you do put it in a pot.