How does an orchid "know" that it is pot bound?
 

I am wondering how an orchid knows when it is pot bound and therefore starts to thrive.

Does the plant have so many roots as to push out most media and make the pot more dry and ventilated?
This implies to me that orchids who want to be pot bound would prefer airier roots.

Does the plant simply have a plethora of roots when it is pot bound, meaning the state of being pot bound is a secondary symptom to a plant already in good health?

Does a pot bound plant have very good stability and feel so secure in its position that it feels comfortable to risk putting out a flower spike?

If you unpot a pot bound orchid without breaking its roots, and then repot it, why wouldn't it stay just as happy (aside from recovering from the shock of a repot)?

I am just wondering how and why the plant knows its pot bound, and why exactly this is beneficial to a plant.

I've read an article from an "industrial" grower, those with labs and a investigation dept. that an orchid with a flower spike (or also a keiki) is a stressed plant that feels itself at risk. So, the flower or keiki are mechanisms to propagate in case of the main plant dies.

Well, that is more along the lines of "couch potato" orchids (see this article). These are orchids that are always too comfortable and never feel any motivation to put out a spike.

It's why things like a night temperature drop, a little too much sun, deprivation of water and fertilizer on winter rests and so on cause a plant to feel small stress and want to make flowers.

However, if a plant is VERY stressed it may not spike at all- for example, a severely dehydrated plant or a very unstable plant may not want to spike. So there's a special little window of stress that will encourage the plant, but too much will probably keep it from spiking?
That's what my thought process is anyway.

An unstable plant might "think" that it is too risky to push out a burst of energy to make flowers, where a lightly stressed stable plant might "think" the risk is justified.

I think lots of roots mean it has a good store and means of getting water to sustain the flowers, since they're the part of the plant that loses most moisture afaik.

This is the article I was talking about.:)

I'm not sure how the process works but your "theory" makes some sense to me.:D

There's actually been a study showing that plants can 'sense' the size of a pot with its roots, though the mechanism is still unknown. Can't link the paper here, but here's a news article about it: Want bigger plants? Get to the root of the matter

This doesn't really answer your question, since in the case of these 'normal'plants in the study, being pot bound actually decreased the size and growth of the plant. Orchids like to behave in exactly the opposite manner...

The results of this study don't surprise me. All the work I've seen on root 'behavior' is quite amazing.Time lapse videos of roots show that that are poking and prodding and searching out the best direction to grow, seeking out the most nutritious areas in the soil. The way the roots move rather looks like a snake or other creature rather than a root. Roots can also sense if neighboring roots belong to kin (sibling) or to a stranger (but still within the same species), and plants can then behave differently depending who their neighbor is.

I have not seen that a pot bound orchid thrives any better or different than a non pot bound one. Case in point: a mounted orchid is not in any pot.

Spikes are for reproduction. When conditions are right, most any life form will reproduce. Even animals, insects, birds and so on will not "ovulate" if conditions are too stressful. In extreem ideal conditions too many young are born, leading to a population crash later on, usually due to over forraging.

If the plant is happy, you will get flowers, if not happy, no flowers. I do not think pot size has any thing to do with this.

I agree with Optimist, with the following addition: a plant needs mechanical stability in order to thrive. That's why it really helps to anchor a newly-repotted plant in the pot. Any slight movement of the plant (even from a slight breeze) will discourage root growth. Once the plant feels stable, whether that is grabbing the pot, spreading out its roots widely, or attaching to a mount, THEN it will put on vegetative mass and will bloom.

I have small phals in very large S/H pots, and their roots don't even touch the pot walls (yet), but there are lots of them stretching in every direction, and they are thriving.

Remembering that in the wild, an epiphite is not repotted again and again. It begins in the same spot on a tree limb and stays their its whole life moving only in its growth direction. We destabilize our own plants. Even if intergenaric or hybrid, it is still unnatural to be moved year after year. The most stable plant is one that is not repotted often. Putting it in a media that does not need to be exchanged and in a large enough pot for future growth is a good start.

If you think of it, the reason people repot is decaying media. I moved to rocks for this reason. Rocks don't decay. And the only reason people use small pots is the media stays too wet. Rocks do not stay wet, so a big pot is fine.

I think it's simply that the root zone of a pot bound orchid dries more quickly than a pot with a lot of space and media.

I think the whole point of keeping orchids in small pots is because of ROT. Smaller pots allow the roots to take up all the moisture with very left over. When a Phal is in a pot that it too big you will see rot as more of an issue.

Orchids in the wild are never restricted the roots are allowed to grow any way and as long as need be.

I wish I could mount all my orchids.

Sorry, gotta disagree. Epiphytes are never constrained in the wild, they will grow over the whole damn tree given a chance. You recommend small pots to people as they usually pack them full of dense material, and the air can't get in. I have been potting phals in BIG pots with just large bark chunks, and they have done well.

I've had rotting issues with phals in bigger pots but I think I used the wrong media. It was more of a medium bark mix with some sphagnum mixed in and it was too moist for my climate.

I wonder if the plants can get more stability faster in a small pot, and when they are stable, they feel happier and like they can thrive?

I like how everyone has a different idea about this!

We can also think the more unstable the medium, the higher tendency for pahls tend to create roots.:D

Well, sphag and phals to me are an invitation to rot. Stability in a pot is important, yes, but I find that mine are very stable.

I am growing one phal in pure sphag and it is totally happy. You just have to know how to use it properly. :)

My problem is that winters here are cold and wet enough to make root rot a real risk, so I tend to pot for summer, where as long asI can water/mist them every day they should be ok. I use sphag in a couple of emergency situations, but I have found that while it works well as a starter, the roots have a problem in winter.

Ideally I would repot them twice a year, shifting them from summer pots to winter ones. Ahaha.

Yes, I know, that way lies madness.

First let's keep in mind, that - excluding the issue of wet+too cold - most "rots" are due to root death caused by suffocation, not simply the exposure to moisture.

Most potting media that are organic based do not wick particularly well, and as essentially all of the evaporation of the contained moisture is from the top and interface with the pot wall, it typically leaves a saturated pocket in the middle - right in the middle of the root mass, so suffocation ensues.

Put that same medium in a net pot, and you are less likely (depending upon your growing conditions) to have that issue, as the drying rate will be accelerated.

Alternately, if you use a medium that wicks really well, like LECA, that saturated "core" will not exist.

Yeah that's what I said they are never restricted.

It is not natural to grow orchids in pots no matter what size it is. Everyone growing area is different what might work for you might not work for me. Also everyone waters a bit differant. Some like to water , Some don't have time. This can cause people to grow orchids differently.

The best way for me to get air to the roots is with lots of extra holes in the pot. I drill extra holes in my pots. The phals I have had problems with were in pots that were too big and did not have extra holes for ventilation.

Sorry, gotta disagree, you're waay over-generalizing the vast diversity of epiphytes, including Orchidaceae and multiple other species-rich families. Many epiphytes and lithophytes do show remarkable preference for confined spaces like hollows and crotches in trees, arboreal ant nests, leaf/frond axils of bromeliads and ferns, tight rock crevices, etc. Likewise some orchids do best for me in narrow, tall pots, others in broad, shallow dishes without drainage, or on various types of mounts, etc etc...

Astrid, are you asking about a specific type of orchid? As posed, your question is too global for a coherent answer, perhaps because you start with the over-general and not universally true assumption that 'orchids thrive when potbound' (some DO seem to, others not). Not trying to be rude; if more specific you pose an interesting question, but as with most things orchid culture it's rarely accurate or useful to speak in broad generalities.

Well, of course we should add the caveat that there is no the slightest guarantee that what works for me, or for you will work for anyone else.

Second, seeds will most usually settle and germinate in a crevice, so few plants will grow on plane surfaces. Lithophytes, not my field, but I find it hard to imagine one that wasn't stuck in a crack.

Generalisations work just fine, as long as you realise that's what they are.

Nope. I just read that "X orchid LOVES to be pot bound" and "Y orchid really loves wearing 'tight shoes' " and "Z orchid only thrives when the pot is bursting in a giant root ball."

And I am curious why people say that and how could a plant "know" if it was pot bound or not. My hypothesis after this discussion is (1) Orchids love stability and will thrive when stable so (2) orchids that are pot bound are very stable indeed also (3) with a huge root ball, there is little media around to stay constantly wet so they are less likely to have any rotting issues.

WRTo 3, surely a compacted ball of roots is likely to suffer from suffocation?

A few great points have been made here.
Let me just add a few things.

First thing first, potbound plants thriving, whoever started saying it, is nonsense. It is one of those things that just float around. Someone said it, heard it, and then just pass it on whether it be online forum or magazine or book...I just hate seeing it all the time still. How annoying!

Especially epiphytes that grow their roots freely all over the tree trunk, there are no bound!

Two, environmental stress causing plants to flower, I find this as a mystery as well. At least temperature.
Drop in temperature helping certain plants to flower is not because the cold shocked or stressed the plant, but certain plants require that drop in temperature at certain time of the year (or depending on the plant, any time of the year) in order to flower the following season, also to stay alive. These plant won't stay healthy for long without proper "winter".

Also, as Camille kindly shared the info, if you were to have a bigger plant, the plant must have bigger root mass to sustain the above the root portion.
Think of bonsai. Or try growing plants very crowded. They will stay quite small or some of them will just die off. Then transplant them into larger pot on their own. You will see a big jump in no time for annuals and other fast growing plants, and a bit more time in orchids but you will see it.

And roots or plants, they know what environment they are in. I find this very very fascinating! :)

I've been hearing that they like to be somewhat pot-bound since day one, so it's quite interesting to understand that that's not exactly true. Now I see that like with so many other things it all depends on multiple variables. But it would seem at the end of the day that it can be dangerous to say they thrive on being pot bound as eventually the plant will not have the space available to grow more roots. I would ask, is it important to getting a plant started for it to be somewhat pot bound?

What does a plant need from its roos? Ignoring support for a moment, it gets water, nutrients and so on.

Look at it logically. If the roots are so tightly packed that no water or nutrients can get in, the root will be less than functional, and if the air can't get in, it will also be dead.

If epiphytes only liked close confinement, then their roots would hardly spread out far and wide.

In short, there are a number of statements made about orchids that are counterintuitive. Tight roots and wetting the crown being the two that spring to mind.

There may be species of orchid that DO like tight confinement. That would be interesting to see if anyone does have such orchids in mind. However, at the risk of making a generalisation, for the average orchid keeper, I think it is safe to say that the less an epiphyte's roots are constricted, the better.

What I'm going after in asking my question is that I have heard some orchids (wish I could be more specific) do not do well if they are 'unstable' in the pot. For instance I have bought plants (online) that arrived in coconut choir which I've found by itself to not be so great for smaller plants without some kind of support. According to what I've heard in the past here such a plant may not grow as fast b/c it's so wobbly in its pot. Thus I ask if with smaller (younger) plants they do well starting out if they have a 'good grip' so to speak on their surroundings?

If makes sense to me that they would because in the wild the plant grows from seed to seedling establishing itself and sending out roots, gaining a firmer hold with each new root and new inch gained. Of course like most natural things they want to be able to spread out so confining it to small spaces for its life I don't believe to be ideal but could it be that this rumor starts out with us growers needing to be able to stabilize our plants and care for them properly until we and they are thriving. If the error never gets corrected than we never expand our experiences to growing in bigger pots...

Certainly people who grow their orchids outdoors on trees do not confine their plants... I would bet people have had rave success keeping plants pot bound b/c they find watering easier so this successful person then passes on their knowledge and... Perhaps it would be a wonderful challenge and experiment for all willing to take a plant we're quite comfortable with and repot it bigger than is recommended (next time it needs repot) while taking medium drying time into account and just letting it be free!!!

Experimentation is the key to find what works best for you.
I think that if an orchid is healthy, and is kept under the right conditions, it will shrug off stuff that would kill it were it weak.

Outside in the wild, every time there is a cool night, and there is mist in the morning, that plant is going to be saturated.

To give you an idea of how penetrative that mist is, I can't use battery powered digital max/min thermometers outside hhere. If I do, cool mornings with mist send moisture right into the electronics and shorts them out.

Yes, and that's why greenhouse growers who pot things like cattleyas and oncidiums among other things, in large slab with long lasting mix that does not need repotting for a very long time, enjoy having huge & happy speciemen sized plants. Or even better, people in the tropics who grow orchids on their trees, just like they would in the wild. Sigh~

---------- Post added at 04:15 PM ---------- Previous post was at 04:07 PM ----------

I also agree with this.
Wetting the plants does not make them spotty or get sudden rot. Disease occur because the growing conditions are not very good and/or plants are just too weak and meant to be doomed. lol

I had oncidiums (many of them are notorious for spots and marks, hence I do not deal with them any more) that I never misted its leaves. They still developed plenty spots and marks.
Then there were certain oncidiums that I always misted and showered, and never had a single tiny spot ever!

I do think however, for plants like phalaenopsis, having water sit on the crown can lead to a problem, although I don't know how true it is (most likely not true hahaha), who wants to experiment with their baby? haha
Wild phalaenopsis grow vertically with their leaves dangling down, so the crown is always facing sideway and water will never sit on the crown. Maybe this is why some people started saying having water on the crown causes crown rot.

There are other environmental factors as well. In the wild, there might be better balance between microorganisms that keep the pathogenic ones population in check. Plus, as soon as the sun rises, the warmth and all the breeze might just dry the plants up quite fast.
And not to mention, in a great growing condition, plants might just be much stronger to fight off invading organisms.

Me. I am sadistic and cruel enough to experiment. I make sure that I ALWAYS wet the crown. Wet it? I fill it. EVERY SINGLE TIME. The only one I have lost from crown rot was one among 6 who were a bit too cold, and who were watered very carefully. I was concerned about them so I kept them as dry as poss. They NEVER had a wet crown.

In addition, I have never found a phal that will hold water. I fill the crowns, they drain out.

In the wild, the crowns will get wet, as mist gets everywhere. I don't water after a certain time, because in the wild I figure they dry out before nightfall usually, and I don't think cold and wet is good. I think it's the cold that does the damage, but moisture will 'up' the chill factor and perhaps push the plant over the edge.

You are from Spain correct? So this is a pretty hot climate. I would be curious to try this in a cooler climate like I have where I live.

Maybe we should get more "cruel monsters" like you experimenting on some cheap phals!! haha!

I once lost a Nelly Isler to (what I think was) erwinia bacteria/ soft brown rot. I blamed myself up and down for getting water in the leaves, but now I realize that it was not my fault at all as I've always been careful. It was just a disease that rotted it.

So many people I know just spray their orchids with water willy-nilly and never have a problem, maybe I should get braver!

Maybe I'll buy a cheap little phal to abuse. XD
I always attach feelings to my orchids so I feel guilty if I harm them even on accident! Like if you step on a dog's foot... it feels so sad!

Last summer I bought a couple of rescue Phals on impulse. Having already grown my collection exponentially in a matter of months I felt rather guilty, thus I didn't immediately attach to them & I left them outside without thinking where I had left them. They got sun burnt really bad as a result. So then I moved them to a shadier place and they stayed out in at least a day of rain (can't remember how long and how much now). As a result within no more than a few weeks (and I think I'm exaggerating) at least one of them showed signs of crown rot. Then they both did. Now more than 6 months later, and one of them dying from the crown rot, the second who lost all above-ground vegetation still has a whole host of green roots in the pot/medium. I continue to care for it to see what happens, although admittedly I haven't watered it in over a week.

I have two Phals I put out in the summer who are doing quite well, those I tilt on their side when it rains so water does not sit in the crown.

I definitely agree that the cold must play into it as well as the overall conditions because I've been to Hausermann's and seen them watering, they don't go out of their way to make sure no water gets in the crowns.

I don't worry too much about how I water all of my other plants though sometimes I wonder when I see water pooled in a new growth, especially if they may be in the cold. While it's rather cool here now but not for too long, the main reason I brought ALL my plants back in is because they've been getting rain for days so they're soaked; I worry leaving them in the cold like this will certainly end badly. :)

Here's a little story. A man was collecting recipes, and a woman was telling him how she cooked this particular ham joint. She started by washing the joint, and then cutting the 'corner' off it. He asked why, and she couldn't give a reason, except that her mother had told her. So, the guy contacted the mother who said that that's how HER mother had taught her. Fortunately the grandmother was still alive, so he went and asked her. She explained that her biggest cook pot wasn't big enough for the whole joint, so she always had to cut the corner off....

There's a lesson there.

To me it is counter intuitive to blame wet leaves. I am more than happy though to listen to anyone who can give a valid explanation. The one I favour is that if the orchid is dangerously close to the coldest it can stand, then wetting it when evaporation will cool it might well push it into cellular breakdown. That of course is wet, and that could quite easily make people thing that the water was the direct cause. I do agree that wetting leaves in cold situations is pretty foolish, but because of the chilling rather than the wetting. Where temps are high enough to evaporate the water without chilling, I think washing the leaves down is a good thing.

Yeah, I'm in South Spain.

I appreciate that rational take on it!

It's hard to find valid scientific studies on orchids, so we're all left to hearsay and opinion I think. I always remind myself that orchids get rained on in nature. The heavens open up and dump water on them, and they're not so careful as to avoid the crown of the plant.

But I have just had it drilled into my head that a wet crown will make a dead plant so now I have to personally experiment and see what happens. Oh how I wish I could just become a botanist and get fatty federal grants to study orchids, but I don't think there's a strong enough interest to justify funding haha!

I guess we should all make the habit of saying, "Hey, where did you learn this information?"

Thankyou. I often hear people counter this by saying "But in nature they hang down." Yeah, but mist and condensation get EVERYWHERE.

I would say to anyone. Get a cheap NOID phal and try and kill it by wetting the crown. Try and fill the crown with water and see if it dies. For the last year, all of mine with the exception of 6 in the garage during the winter have had their crowns filled every time they get watered. The only one that did get it was one of the garage ones whose crowns were kept dry all the time because they were so cold there.

If you accept everything you are told blindly without experimenting, you will get stuck with all sorts of dodgy info.
It's one of the advantages of being taught science. a) it teaches you to question, and b) it gives to the tools to question with.

I often repot into what most people consider to be "too big of a pot". I do it w/my catt alliance regularly because I think they do better when left undisturbed as long as possible. BUT...I pot into media that doesn't break down AND my media of choice (usually leca or lava rock) dries fairly quick.

Below is a pic from sometime in the spring 2011 when I took a B nodosa out of a teak basket and let me tell you...it was quite the surgery. I ended up w/3 plants (2 of which have since found new homes)...the piece I kept is in the "bowl" in the back of the pic. This was taken when I finished the surgery that year. As you can see, the pot is far bigger than what most people would consider "acceptable" for the size of the plant. It's potted in leca and that is a sheet moss layer on top.
http://i405.photobucket.com/albums/p...s/nodosa_C.jpg


This is the same plant - taken July 2013 - I can't find last year's pic but it's now growing out of the pots.
http://i405.photobucket.com/albums/p...psa265a07e.jpg

A bit over 2 yrs and it's pretty much filled that pot. Today - 4yrs after the surgery - it's growing outside the pot and invading it's shelf mates. I think we can all agree...it seems quite happy having room to spread out.

I think the key w/"tight shoes" is more about making sure the plant isn't over-watered. A "too big" pot and medium that hold moisture = death to most roots. Use a media the drains and dries fast and secure the plant properly and a "too big" pot isn't going to hurt the plant in the slightest. At least not in my experience.

Beautiful plant. The more I read about this, the more I am convinced that in most cases, the only thing that matters is, "Can the roots breathe and get enough water?"
Beyond that, size is irrelevant.

This is the same reason I use red lava rock. You can put the tiniest seedlings in red lava rock and a large basket pot and never worry about the roots rotting as there is always going to be plenty of air getting to them. You can leave the orchid in that and, when it needs a larger pot, just drop the entire thing into the larger pot, never disturbing the roots.

Crown rot. Many orchids live where it is humid, rains and even in places with cooler temperatures but what prevents crown rot in these situations in the breeze. The same goes for preventing fungus attacks with many other plants. That is why, in large commercial greenhouses, you usually have fans running.

Is that the case, or is it that air movement allows for cooling in high humidity? I just don't see a healthy, happy plant succumbing to crown rot thru moisture. What I do see is a plant that is stressed, or damaged thru high heat/cold suffering tissue damage, and it being that tissue damage that allows the fungus access.

It depends on what you are growing, I think. Some orchids are much more resistant while others...not so much.