# New roots for new mix.



## Stone (Aug 6, 2012)

Can anyone give me THE REAL reason why new roots are stimulated whenever we change the potting media?
I don't think its a build up of salts because it happens even after the plant has been thoroughly flushed and leached for months with no fertilizer added at all.
Is the old mix inhibiting new roots in some way or is the new mix stimulating them?
Is there a build up of microbes which release some sort of inhibitor?
We have all seen it but I've not really read a convincing reason why it happens.
Rick, you might say that its a build up of K, but I'm still seeing it on seedlings recently repotted which have only been fed with the tiniest bit of blood and bone over winter (0%K). So why is it so???
Case #1 A compot of 4 bellatulums which did well over summer, then slowed down in autumn and stopped by winter. and thats what you would expect. then they were placed on bottom heat under lights and went into suspened animation until last week when I repotted them into thumb pots and within 3 DAYS!!!!!! new roots on three of them!!! The mix was basically the same.
Case #2 A compot of sanderianums....Same thing. #3 fairrieanums in small pots. Mix changed....well you get the idea...
If we can come up with the correct reason, we might go a long way in improving our successes.
It's keeping me up at night
Please exuse the drawn out post.
Mike.


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## ehanes7612 (Aug 6, 2012)

probably humidity/water content , a new mix is going to be less humid than an old broken down mix and will also have less water retention..but the plant will also want to replace any roots damaged in the repotting, and you cant discount that even a new (same ) mix is not the same in mineral content and concentrations of N/P/K as the old broken down mix...and plants tend to adapt by replacing parts


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## Stone (Aug 6, 2012)

But the replaced mix was not broken down in the slightest. In fact in the case of the bellatulums, it was baked clay, some bark some charcoal and polystyrine. It looked the same as when I put it in!
And I took extreme care in repotting. Almost placing the pieces in one by one.


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## eggshells (Aug 6, 2012)

My theory is the plant wants to anchor itself into the new medium and want its itself to be stable. This is the functions of roots after all other than for nutrition uptake is to anchor the plant to a substrate.


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## Roth (Aug 6, 2012)

I have plants in Orchiata for some years, not repotted, and there are still a lot of active roots... In Europe, there are many growers that used to repot their paphs when they had really outgrown their pots, I still remember some of Ratcliffe paphs that were potted for at least 5 years, if not more.

Apart from simple things to correct, like media acidification, for which Ratcliffe and most EU growers used to apply lime as frequently as every other month, new potting mix contains some oligos that we do not dare to supplement in the fertilizer, may it be chlorine, sodium, or whatever... I found out on the other side that paphs that had stopped root growth suddenly restarted like if repotted in a fresh mix if I added boron. The more calcium you supplement as calcium nitrate or lime, the more the boron is likely to be deficient, and it is very efficient at stopping root growth instant when it drops below a critical level, more even than a calcium deficiency. 

Water retention, etc... are not the cause, some people grow extremely wet their paphs, and they root like crazy indeed... I think that apart from the pH and EC, that can be corrected easily, it is just a micronutrient deficiency, nothing more. I got some analysis of several 'old potting mix' where the roots would not grow further, and usually the molybdenum, boron, and in quite a few cases copper levels were much lower than fresh mix, apart from that, it was pretty much the same as the new one...

I think it is the main basis of the Norman's Orchids new Turbothrive.


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## keithrs (Aug 6, 2012)

My theory is that in nature paph.'s will tend to grow new root as seasons change and leafs fall. The plants want to take advantage of the new leaf mold. My theory may be novel!?!


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## Stone (Aug 6, 2012)

Roth said:


> I have plants in Orchiata for some years, not repotted, and there are still a lot of active roots... In Europe, there are many growers that used to repot their paphs when they had really outgrown their pots, I still remember some of Ratcliffe paphs that were potted for at least 5 years, if not more.
> 
> Apart from simple things to correct, like media acidification, for which Ratcliffe and most EU growers used to apply lime as frequently as every other month, new potting mix contains some oligos that we do not dare to supplement in the fertilizer, may it be chlorine, sodium, or whatever... I found out on the other side that paphs that had stopped root growth suddenly restarted like if repotted in a fresh mix if I added boron. The more calcium you supplement as calcium nitrate or lime, the more the boron is likely to be deficient, and it is very efficient at stopping root growth instant when it drops below a critical level, more even than a calcium deficiency.
> 
> ...



After studying the Calcium/Boron relationship, I have been giving boron more often. Especially when using Calnitrate or dolomite. A tiny pinch in some hot water and then into the watering can. Not very scientific but so far no problems. But I've only been doing it for a couple of months so I cannot really tell if its making a difference. I have not tried the Mo yet.


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## cnycharles (Aug 6, 2012)

if you want to see if it's something mechanical, take the plant out of it's media, rinse the roots, and then put it back in the same media. if the plant starts growing roots again then in that case it's something mechanical where the plant is responding to the movement against the roots/plant (or you are temporarily increasing large pore space). you could do a plant with washed media, another just dumping out and putting back in. if nothing happens by moving the media around then it's something chemically based, most likely


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## Stone (Aug 6, 2012)

keithrs said:


> My theory is that in nature paph.'s will tend to grow new root as seasons change and leafs fall. The plants want to take advantage of the new leaf mold. My theory may be novel!?!



Yes but in a glasshouse with seedlings on bottom heat and lights, the seasons go out the window.


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## cnycharles (Aug 6, 2012)

to us the seasons may not exist, but plants have their own timer. a species can flower at the same time all around the world, even if they are in different growing conditions (lights on timers etc)


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## Stone (Aug 6, 2012)

cnycharles said:


> if you want to see if it's something mechanical, take the plant out of it's media, rinse the roots, and then put it back in the same media. if the plant starts growing roots again then in that case it's something mechanical where the plant is responding to the movement against the roots/plant (or you are temporarily increasing large pore space). you could do a plant with washed media, another just dumping out and putting back in. if nothing happens by moving the media around then it's something chemically based, most likely



Yes washing the roots seems to stimulate them. But I can only say ''seem'' because after washing they go into the new media. Please don't make set up another trial:sob:


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## Stone (Aug 6, 2012)

cnycharles said:


> to us the seasons may not exist, but plants have their own timer. a species can flower at the same time all around the world, even if they are in different growing conditions (lights on timers etc)



Yes thats true. I remember years ago I had three plants of bamboo in three different pots. All divisions of the same plant. One was outside, one was indoors and one was in the g/house. After about 5 years they all flowered simultaneously! ..... and then all died.
But the response on the paphs was not seasonally based coz this is our darkest and coldest month! yet the roots came.


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## cnycharles (Aug 6, 2012)

Stone said:


> Please don't make set up another trial:sob:



:rollhappy: so many 'trials' here on slippertalk... what's the final verdict of it all?


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## SlipperKing (Aug 7, 2012)

cnycharles said:


> if you want to see if it's something mechanical, take the plant out of it's media, rinse the roots, and then put it back in the same media. if the plant starts growing roots again then in that case it's something mechanical where the plant is responding to the movement against the roots/plant (or you are temporarily increasing large pore space). you could do a plant with washed media, another just dumping out and putting back in. if nothing happens by moving the media around then it's something chemically based, most likely


I do this quite frequently Charles with the whole collection and yes; new roots always follow. It's just of matter of new air pockets opening up and the plants re-anchoring themselves. I do this to loosen up the mix, clean out the algae growth from the sides of the clear pots and then wash out the "mud" (broken down mix) from the pots.


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## keithrs (Aug 7, 2012)

Stone said:


> Yes but in a glasshouse with seedlings on bottom heat and lights, the seasons go out the window.



I don't think its the seasons change that trigger it but the build up of leaf litter or what the plant thinks is a build up of litter. When you repot you may be telling the plant at new food has fallen. It may even trigger new growths. Season change will trigger leafs to drop in nature just like some orchids... Well most orchid to flower... Some paph may have a very mild season change(like in a greenhouse).


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## keithrs (Aug 7, 2012)

SlipperKing said:


> I do this quite frequently Charles with the whole collection and yes; new roots always follow. It's just of matter of new air pockets opening up and the plants re-anchoring themselves. I do this to loosen up the mix, clean out the algae growth from the sides of the clear pots and then wash out the "mud" (broken down mix) from the pots.



Stick a couple worms in your pot... They'll do the work for you!


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## jtrmd (Aug 7, 2012)

SlipperKing said:


> I do this quite frequently Charles with the whole collection and yes; new roots always follow. It's just of matter of new air pockets opening up and the plants re-anchoring themselves..



I agree


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## SlipperKing (Aug 7, 2012)

keithrs said:


> Stick a couple worms in your pot... They'll do the work for you!



Damn! I hate that gooie feeling! With these six inch air cone pots I use, occasionally I'll carry a plant by one hand. To steady the pot on one hand I'll stick a finger in the center cone. Damn if a slug ain't up there hiding out! YUCK!


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## Stone (Aug 7, 2012)

jtrmd said:


> I agree



Given that plants use a manipulation of hormones for their growth activities, moving or disturbing thier roots COULD activate gibberellin and lead to root initiation, which would make the response to repotting chemically based anyway. So, in theory if we went around and squeezed the pots from time to time we should see the same response? Or if we added gibberellin...likewise.
But I wonder if its that simple. And which, how many, and in what concentration of hormones are involved?
I have seen many times new roots start on orchids that have just sat there for month after month when I tipped out the top layer of mix and gave the pot a really good flush out with the hose. Thats what makes me think there might by some unseen fungus or microbe releasing some kind of inhibitor.
The trouble is that no one really knows what the plant SHOULD be doing, only what it does. Eg: How seasonal is paph root growth and how do they grow in the habitats?


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## Rick (Aug 7, 2012)

Wow Mike lots of moving variables in this one.

The ion exchange capacity, nutrient makeup, water retention/aeration properties, pH and pH drop, loss of natural hormones, and bacterial flora vary considerably on the make up of your mix components. The semi hydro folk with clay balls have about the simplest system, and they run substrates for years without needing to change substrate for root growth (which can still be seasonal).

The K buildup issue is bigger for CHC users than bark users, and even less of an issue if your flush water has a noticeable calcium magnesium concentration.

pH not only controls nutrient uptake directly, but also changes the bacterial/fungal ecosystem of the mix. I've talked about the basket system quite a bit, and monitoring it for over a year now. Several plants started as early as 12/2010, but I think most of my slippers are in baskets (out of compots). In cases where the plants roots made it all the way to the outside of the basket, these plants are just charging along without changing any moss. Even after more than a year. In cases where I used large baskets with small root masses it looks like a lot of the initial growth momentum stalled. In several cases after flushing with straight (crusty well water) stalled plants took off. In other cases I repotted the stalled plants (generally with non active but OK roots) in smaller baskets with a higher percentage of limestone chips for extra aeration, and they've taken off again.

Now I'm running summertime and getting some day peaks as high as 94 in the GH. But you are in winter now, and not sure what to expect for your winter temps anyway.

Back to microfloral community, a handful of years ago I experimented with some myhcorrizae inoculates. In a couple cases of stalled compots they "came back online" as you describe, without changing the potting mix. But this was not universal for every plant or compot I tried it on. A few already messed up plants went ahead and died.

I don't think there is any one single REAL reason why an aged potting mix will inhibit root growth.


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## Stone (Aug 7, 2012)

Rick said:


> > I don't think there is any one single REAL reason why an aged potting mix will inhibit root growth.[/
> 
> 
> 
> ...


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## Rick (Aug 7, 2012)

Stone said:


> Case #1 A compot of 4 bellatulums which did well over summer, then slowed down in autumn and stopped by winter. and thats what you would expect. then they were placed on bottom heat under lights and went into suspened animation until last week when I repotted them into thumb pots and within 3 DAYS!!!!!! new roots on three of them!!! The mix was basically the same.
> 
> Mike.



Mike When you say the mix was basically the same do you mean its the same type of mix or you just moved them in old mix to new pots?

If you didn't change the mix then you might consider the aeration/compaction issues. Which can change chemistry pretty fast too.

If you changed out the mix (even if its the same type as previous), then all kinds of things got changed.


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## Rick (Aug 8, 2012)

Stone said:


> Maybe not but the answer must be less complicated than we might think considering how wide spread this phenomenon is. It dosen't seem to be affected by different media either or water or air or fertilizer. But it just happens time and time again. In fact I doubt its even a combination of factors.
> I didn't really expect to get an absolute indication. I think the Boron thing as Roth mentioned or the hormone mobilization MIGHT be the key?



You have a lot of mounted plants. If they stop growing roots do you remount them to stimulate new roots? Probably not. They probably develop roots on the same mount or basket for years on end with some seasonal ebb/flow. And since there is no mix around the roots, how come they don't experience nutritional (boron for instance) deficiencies like a potted plant in mix supposedly would. Similarly where is the hormonal mobilization coming from for a mounted plant? These were the questions and observations which pushed me to try baskets for paphs after years of trial and error with various pots and mix combinations.

In comparison to how good open rooted plants do (mounted/baskets/semihydro) for years without repotting, I would look more towards some type of inhibitory effect from old mix in potted conditions.

I did a few side by side tests of basket versus potted plants using the exact same ratios of moss/grave/sand. The baskets won hands down for root growth. But I can't tell why/what/how the extra aeration is doing to the chemistry or biology of the media.


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## Stone (Aug 8, 2012)

Rick said:


> If you changed out the mix (even if its the same type as previous), then all kinds of things got changed.
> 
> Yes I changed the mix, so what are these all kinds of things? The old mix was not broken down, pH was about the same.


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## Stone (Aug 8, 2012)

Rick said:


> You have a lot of mounted plants. If they stop growing roots do you remount them to stimulate new roots? Probably not. They probably develop roots on the same mount or basket for years on end with some seasonal ebb/flow. And since there is no mix around the roots, how come they don't experience nutritional (boron for instance) deficiencies like a potted plant in mix supposedly would. Similarly where is the hormonal mobilization coming from for a mounted plant? These were the questions and observations which pushed me to try baskets for paphs after years of trial and error with various pots and mix combinations.
> 
> In comparison to how good open rooted plants do (mounted/baskets/semihydro) for years without repotting, I would look more towards some type of inhibitory effect from old mix in potted conditions.
> 
> I did a few side by side tests of basket versus potted plants using the exact same ratios of moss/grave/sand. The baskets won hands down for root growth. But I can't tell why/what/how the extra aeration is doing to the chemistry or biology of the media.



For the mouned plants the environment is totally different than inside a pot. These are what I regard as true epiphytes with photosynthetic root tips etc like Phals and Catts etc. What's more they're not surrounded by plastic and constant moisture so its hard to compare the two. Paphs growing in trees are really just in the same moss and humus as the ones on the ground/rocks.
Maybe their (true epiphytes) roots have evolved in a totally different manner than the ''humus epiphytes'', and are not subject to the same nutritional requirements? I don't know. BUT.. I have seen the same thing in repotted Catts as well which points to an inhibitor of some sort from the aged mix as you said.
But also repotting catts does damage the roots and this could cause the hormone stimulation.
I'm not saying that the potted plant doesn't grow seasonal roots..of course it does, but what I'd like to know why new roots are formed so quickly after repotting and it can be a matter of DAYS after it has moved to a fresh mix even after no root activity for many weeks or months!!
Something is telling the plant ''OK you can go ahead and root!!!'' I should add that top growth seems to keep moving slowly on regardless. Which points to more chemical shenanigans in the pot


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## Rick (Aug 8, 2012)

Yup on a lot of your observations in your last post but also consider that I have mounted and baskets of Dendrobiums, Bulbophylums, Catesetums, Gongoras, ...all "true epiphytes" with non photo synthetic roots. Also several paph species like sanderianum and henryanum will be attached to cliff faces with roots (non-photosynthetic) totally exposed to sun and air (not burried in humus). My basket sanderianums have jumped way ahead since coming out of pots.

The phal example is interesting in that before K lite I could never keep a phal in a pot no matter how careful I controlled watering. But mounted they do just fine (but much better since K-lite). But since K lite I have several phals (like that mannii I just posted) that have been in the same pot of moss (or bark in a few other cases) for 2 years now. And still growing leaves and roots. Granted there are lots of roots developing outside of the substrate so for all intents and purposes they are "mounted" on a pot that happens to be full of some old mix. But at least now they don't seem to be inhibited by whatever chemical highjinx are going on in the pots.


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## SlipperFan (Aug 9, 2012)

Rick said:


> ...The phal example is interesting in that before K lite I could never keep a phal in a pot no matter how careful I controlled watering. But mounted they do just fine (but much better since K-lite). But since K lite I have several phals (like that mannii I just posted) that have been in the same pot of moss (or bark in a few other cases) for 2 years now. And still growing leaves and roots. Granted there are lots of roots developing outside of the substrate so for all intents and purposes they are "mounted" on a pot that happens to be full of some old mix. But at least now they don't seem to be inhibited by whatever chemical highjinx are going on in the pots.



How do you know what's going on in the pot unless you take the plant out of it?


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## Ray (Aug 9, 2012)

My view is a bit more basic.

On a cellular level, roots tailor themselves to function optimally in the environment into which they grow. That is the key to survival.

Change the environment around the roots, and the current ones may no longer be optimal, so the plant does what it can to correct that, by growing new ones.


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## Stone (Aug 9, 2012)

Rick said:


> > The semi hydro folk with clay balls have about the simplest system, and they run substrates for years without needing to change substrate for root growth
> 
> 
> 
> ...


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## Rick (Aug 9, 2012)

SlipperFan said:


> How do you know what's going on in the pot unless you take the plant out of it?



Agreed. The roots still in media may be dead and gone, and the plant is just using the pot as a mount, like any other piece of bark. But what's going on in the pot seems to be irrelevant these days compared to the past. In years past, potted phals never grew new roots (above or below the media) and when they looked stressed, I pull them out of the pots generally to find a pretty traumatized plant.

Now they are never sick. They just keep getting new leaves and roots (granted usually above the media though occasionally I do see new roots heading into the media). So I don't have any reason to take them out of the pots for root inspection or repotting. If they are in clay plots then I worry more about breaking and tearing roots that have attached to the clay pot.


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## SlipperFan (Aug 10, 2012)

Rick said:


> Agreed. The roots still in media may be dead and gone, and the plant is just using the pot as a mount, like any other piece of bark. But what's going on in the pot seems to be irrelevant these days compared to the past. In years past, potted phals never grew new roots (above or below the media) and when they looked stressed, I pull them out of the pots generally to find a pretty traumatized plant.
> 
> Now they are never sick. They just keep getting new leaves and roots (granted usually above the media though occasionally I do see new roots heading into the media). So I don't have any reason to take them out of the pots for root inspection or repotting. If they are in clay plots then I worry more about breaking and tearing roots that have attached to the clay pot.


Pretty interesting. My problem with that is that Phal roots outside pots get all tangled up in each other and want to go into their neighbor's pots. Gets pretty messy.


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## emydura (Aug 11, 2012)

SlipperFan said:


> Pretty interesting. My problem with that is that Phal roots outside pots get all tangled up in each other and want to go into their neighbor's pots. Gets pretty messy.



I know exactly what you mean.


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## Ray (Aug 11, 2012)

I'm not going to go back and reread this entire thread, so if this is a repeat, I apologize in advance.

I think another reason we see new root growth after a repot is that we likely damaged the existing roots in the process, which probably elicits a "save yourself" response to produce new ones.


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## Ray (Aug 11, 2012)

SlipperFan said:


> Pretty interesting. My problem with that is that Phal roots outside pots get all tangled up in each other and want to go into their neighbor's pots. Gets pretty messy.



Upon realizing that LECA wicks so well, you don't get a "soppy core" in the pot, I started moving my phals into pots as big as their leaf spans (if I can find large enough pots). Ever since doing so, I get no aerial roots whatsoever - they all just go down into the medium.


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## SlipperFan (Aug 11, 2012)

Ray said:


> Upon realizing that LECA wicks so well, you don't get a "soppy core" in the pot, I started moving my phals into pots as big as their leaf spans (if I can find large enough pots). Ever since doing so, I get no aerial roots whatsoever - they all just go down into the medium.


Interesting. Are you using your regular S/H plastic pots or something different?


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## Ray (Aug 12, 2012)

Regular S/H pots, Dot


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## newbud (Aug 12, 2012)

Hey Rick - Tell the folks about that lady in Tenn. that never changes nothing for 50 years and all her orchids are fine.


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## Rick (Aug 12, 2012)

newbud said:


> Hey Rick - Tell the folks about that lady in Tenn. that never changes nothing for 50 years and all her orchids are fine.



I've mentioned her several times Jack.

It's not that she never changes anything, but she never fertilizes. I know she has repotted many things over the years (especially as the chids out grow pots). But in many cases some things never do get repotted, and the pots crack with the plants rooting into the benches.


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