Soft, droopy leaves after repotting

[james mickelso]

Ray, do you think that roots are taylored to a particular media? I don't think so. The root should be the same no matter what it is growing in. The velamen should have the same porosity no matter what. I don't see a difference in the structure or growth whether in moss or bark. Do you find a difference? I have always thought that it is the micro-environment close to the root surface that is the difference between the various media. I know some who grow many different orchids in moss yet I can't and I think it is because where I am it is humid and cool. Whereas someone in say Texas or Ontario, Cn may be warmer and dryer. They might be able to grow in moss but not course bark. They may have to grow in fine bark where I can't without jeopardizing the roots. If you see a difference in roots let me know. That may answer some questions I have. Like when I get the phals from HD or Lowes and have to take off dead or mushy roots, if I put them in medium bark with sponge rock they perk right up (for a plant that has had major surgery anyway) but if I put them in fine bark without sponge rock they suffer. It'd be interesting to see why the difference. Here are some phals I repotted two weeks ago and they are still ok with little change in them. I have some others that were repotted this past weekend and are too new to tell if they will deteriorate as I had to trim off more roots due to rot. I potted these in medium bark, sponge rock, and charcol. You can see the sizes in comparison to my finger. The moss is there to keep the bark from falling out of the phal planted horizontally and the phal with the moss on top I put some to help keep the dampness in the pot. But you can see the large holes I put in the side of the pot to help dry the media out. I only water these when the pot becomes light weight. That may be once a week. I think a lot of the problems people have when they repot an orchid from HD or one they have been given is that they tend to keep it too wet. What do you think? How do you repot yours?

[Ray]

Geez, James. Do me a favor and use the return/enter key to make paragraphs! That's tough to read as one giant one.

Orchid roots tailor themselves on a cellular level to the environment they are in, not to the medium specifically. Some of the more significant differences are in the permeability of the cells to water and gases.

Rod Venger (of the formerly Venger's Orchids in Colorado Springs), who originated "water culture" delved into this with some PhD candidates at Texas A&M who actually did some research in the area. I had a copy of the study summary, but have no idea where it got off to.

Everything is a matter of degree. If I move a plant from sphagnum to straight bark, for example, that environment is very different, so the existing roots (having low water permeability, due to the readily available supply, and high gas permeability to overcome the restricted accessibility of the compact moss), may "struggle" to take up enough moisture in the bark environment, and the high gas permeability can lead to severe water loss for the plant, so new roots that can absorb more readily are essential.

If I move that same plant into S/H culture however, the "new" and "old" environments aren't all that different, and the urgency for new roots isn't there. The current roots may not be optimal, but they are "good enough" for the time being.

I don't think the wet/dry issue is related solely to the plant. Don't forget the folks that successfully grow in the constantly-wet S/H culture, or more extreme, in water culture where the roots are totally submerged. Consider this:

How does the potting medium react to the watering load? If the medium is compact or uses a lot of fine-grade ingredients - or has decomposed to become fine and compact - the spaces between particles are small. Surface tension is therefore capable of holding water in those spaces, completely blocking them and stifling the air flow to the roots that is so essential to their functioning and survival. Allow it to dry - large hoes in the pot, lots of air movement, and lower humidity enhancing that - and the spaces open up again and let the roots "breathe". (I firmly believe that the lore that "orchids have to dry out between waterings" is based upon a misinterpretation of that phenomenon.)

I suspect that your "perking up after repotting" observation is less related to root morphology, and more to stress relief. I have seen it myself, both with orchids and with terrestrial plants being divided and repotted in the same soil - no "tailoring" needed then. The differences seen when comparing plants repotted into different media might be simply one of moisture availability during the "perking" process.

[james mickelso]

Thank you. Sorry about the run on sentences and non paragraph divisions. I can build a house or motor without plans or specs but writing is not my forte. I'm good at spelling but not writing. I, like you, enjoy more in depth discussions and scientific explanations for that in which I am interested. I still don't quite understand water culture and semi hydro. I have tried to grow some very finicky orchids, not following excepted methods of cultivation and lost them right away. Again thanks for the detailed explanation.

[Ray]

Originally Posted by james mickelso

Thank you. Sorry about the run on sentences and non paragraph divisions. I can build a house or motor without plans or specs but writing is not my forte. I'm good at spelling but not writing. I, like you, enjoy more in depth discussions and scientific explanations for that in which I am interested. I still don't quite understand water culture and semi hydro. I have tried to grow some very finicky orchids, not following excepted methods of cultivation and lost them right away. Again thanks for the detailed explanation.

You sir, and I need to go out and discuss stuff over a glass of our favorite "imbibement".

[james mickelso]

Indeed it would be fun and enlightening. And you would enjoy the young women strolling the beach at sunset here.