# Does anyone grow paph/phrag in rockwool with success??



## Happypaphy7 (May 15, 2019)

Either rockwool only or rockwool mixed with other stuff like clay balls or perlite? 
I have read people having success growing Miltoniopsis in rockwool only. 
Someone here (Tom Kalina I think?) said he grew phrags in rockwool but phased out of it. I wonder what happened? 

Input please!! 
Thanks in advance.


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## monocotman (May 15, 2019)

Most of my phrags are in rockwool. The wet medium works well indoors growing plants in low humidity.
OL have most of their phrags in rockwool.
I use the minicubes and add a bit of perlite.
David


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## mrhappyrotter (May 15, 2019)

I use rockwool. Well, technically, I use a rockwool based mix, with other components like sponge rock, charcoal, orchiata, leca, and other stuff. I basically mix in whatever's available and cost effective. I think other folks like the Fishers (i.e. OrchidWeb) use a straight rockwool mix for small growing Phrags and Phrag seedlings.

For Phrags, I go heavier on the rockwool. For Paphs, I go a little lighter on it. Parvies love it. Seedlings love it. Smaller sized plants love it.

I first started using it because it was the most cost effective potting mix for me. I was having to get potting mix shipped to me, and rockwool is so lightweight that once I factored in shipping costs, it was the least expensive potting media by volume (per cubic foot). Eventually, I was growing most of the slippers in rockwool. 

However, more recently I've started experimenting more with other potting mixes and ingredients, so I've reduced the number of plants I grow in rockwool. Part of the reason is that as my collection has started to age, I have a number of big plants that I don't necessarily want to divide. I find it harder to properly water giant pots full of rockwool. The other issue I encountered is that I think I got a bad batch several years ago. It seemed like nothing would grow in the stuff, plants struggled after repotting, and root systems failed to thrive. I'm unsure why, since pH and TDS were good. I'll note that bad batch syndrome happens with pretty much any potting media from time to time. You'll get bark that rots to mush in less than a year, leca that crumbles to mud, sphag that rots within months, etc. Even so, it's made me nervous to rely solely on rockwool, so I'm basically hedging my bets.

Overall, I think the pros and cons are...

Pros: It's easily available locally (for me). If it's not available locally, it's still one of the most cost effective potting mixes once you factor in shipping costs because it's so lightweight. It holds moisture while still providing lots of air space. It's easy to tell when to water because the weight difference between wet and dry rockwool is very noticeable. It doesn't rot or break down, so you can go longer without repotting. Paphs and Phrags love it.

Cons: It must be properly prepared before use, soaking and rinsing is required, and it may need pH adjustment. Regular flushing with pure water is required since it's prone to mineral/nutrient build-up. Careful fertilization is important because of the mineral build-up concerns but also because rockwool doesn't provide any nutrition to the plants they are more reliant on fertilizers and nutrient deficiencies can pop up quickly.


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## Happypaphy7 (May 15, 2019)

monocotman said:


> Most of my phrags are in rockwool. The wet medium works well indoors growing plants in low humidity.
> OL have most of their phrags in rockwool.
> I use the minicubes and add a bit of perlite.
> David



Thank you for the input, David. 
Do you treat rockwool before use and also every so often? I remember someone here mentioning the ph adjusting with certain solutions. 
I have also heard someone saying he does not treat rockwools cubes at all and use as is. I'm not sure which one to follow.
I see small cubes (minicubes as you say) available, 3/8 to 1/4inch particle size, right? 
Do you mix it with some other stuff or just straight rockwool cubes?


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## Happypaphy7 (May 15, 2019)

Thank you for detailed reply. 
By the way, I thought one of the benefit of using rockwool was not having to repot thus good choice of mix for growing plants large for years?
I would think that the roots will adhere to the rockwool (inside and outside of rockwool cubes) and it would be very hard to repot the plant without inevitably damaging lots of root?
Or do the roots separate quite easily from rockwool? 

So far, I've never had bad experiences getting potting mix that was in less than optimum conditions with the exception of chc mix by this one vendor. I used CHC based mix extensively with great results. Then, one year, the batch was not as good. The difference was visually obvious. I contacted the vendor and was told it is the same quality, which clearly was not. So I stopped buying the stuff and switched to orchiata based mix since. Happy!  
Just curious about using rockwool cubes for certain plants now. 




mrhappyrotter said:


> I use rockwool. Well, technically, I use a rockwool based mix, with other components like sponge rock, charcoal, orchiata, leca, and other stuff. I basically mix in whatever's available and cost effective. I think other folks like the Fishers (i.e. OrchidWeb) use a straight rockwool mix for small growing Phrags and Phrag seedlings.
> 
> For Phrags, I go heavier on the rockwool. For Paphs, I go a little lighter on it. Parvies love it. Seedlings love it. Smaller sized plants love it.
> 
> ...


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## monocotman (May 15, 2019)

I use the rock wool straight out of the bag. No treatments. I’ve added a bit of perlite but it’s difficult to mix so some of the pots have little perlite. It doesn’t seem to make any difference.
Repotting phrags in rockwool is very easy. The mix just falls off the roots. As rock wool is inorganic I would hope that it would be much more consistent than an organic mix and there would be very little variability from batch to batch.
Like you I also use orchiata, but this time for my cattleyas.
David


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## Tony (May 15, 2019)

After some discussion and advice from Ed (ehanes7612) I switched to rockwool and perlite and couldn't be happier. I have struggled with organic media after moving to SC, none of them hold up to the heat and the amount of water the plants need here. Along with the media change I adopted Ray's protocol of K-lite, KelpMax and Inocucor, set up my spare RO unit to provide pure water and added a swamp cooler to my greenhouse. Too many changes to isolate any one factor as a "miracle", but thet have resulted in the absolute best growth I've ever seen in my 25+ years of growing orchids.


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## ehanes7612 (May 15, 2019)

I find a mix with at least 50% rockwool to be more forgiving if you forget to water. I probably use a 50/50 perlite /rockwool mix, although I have started to reintroduce some large bark chunks (about 10 percent) because I cant find large perlite chunks...small grade perlite clumping seems to cause concentration zones that affect water retention, ...the bark helps to break it up as the perlite moves around and settles with each watering


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## Tony (May 15, 2019)

ehanes7612 said:


> I cant find large perlite chunks



Have you tried LECA? I'm having the same problem finding perlite and grabbed a bag last time I was at the local hydro shop.


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## ehanes7612 (May 15, 2019)

I havent although I have bought brachys with leca in them , growing really well


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## Tony (May 15, 2019)

It makes a nice airy mix for bigger pots.


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## ehanes7612 (May 15, 2019)

yeah, i figured


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## mrhappyrotter (May 15, 2019)

Happypaphy7 said:


> Or do the roots separate quite easily from rockwool?.



Generally, yes. A little bit will stick here and there, but most of it falls off easily when swished in a bucket of water. Of course, Phrag roots are so pliable and break resistant that it's not a concern at all for them. Parvies obviously have more brittle roots, but I've never had issues with rock wool. I use the small croutons. I know there are bigger sizes available, but I don't know of a local source and I've never sought out any other size online.


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## Ray (May 16, 2019)

Can you please provide more info about the rockwool cubes you use?


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## Tony (May 16, 2019)

https://grodan101.com/products/grodan-stonewool/loose/grow-cubes


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## Happypaphy7 (May 17, 2019)

mrhappyrotter said:


> Generally, yes. A little bit will stick here and there, but most of it falls off easily when swished in a bucket of water. Of course, Phrag roots are so pliable and break resistant that it's not a concern at all for them. Parvies obviously have more brittle roots, but I've never had issues with rock wool. I use the small croutons. I know there are bigger sizes available, but I don't know of a local source and I've never sought out any other size online.


 
Wow~ This is great to know! I assumed that the roots will adhere to the rockwool cubes and grow firmly on the surface of them as well as penetrate inside them. So This is really a great piece of information. 
Thank you!


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## Happypaphy7 (May 17, 2019)

Than you for the detailed information regarding your regime and the photos. I'm glad that you are having such success! 

And thank you everyone for chiming in. 
Keep it going, please!


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## Ray (May 17, 2019)

When I experimented with Grodan cubes years ago, it was available in hydrophilic and hydrophobic versions, so you were able to blend them in your preferred ratio. Apparently that's no longer the case.


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## southernbelle (May 17, 2019)

ehanes7612 said:


> I find a mix with at least 50% rockwool to be more forgiving if you forget to water. I probably use a 50/50 perlite /rockwool mix, although I have started to reintroduce some large bark chunks (about 10 percent) because I cant find large perlite chunks...small grade perlite clumping seems to cause concentration zones that affect water retention, ...the bark helps to break it up as the perlite moves around and settles with each watering


I use the mixture Orchid Web recommends for phrags. 65% ¼” rock wool; 35% perlite; 10% fine charcoal. Just transplanted into this for my 4 phrags. Will report on success later.


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## spujr (May 18, 2019)

Tony said:


> After some discussion and advice from Ed (ehanes7612) I switched to rockwool and perlite and couldn't be happier. I have struggled with organic media after moving to SC, none of them hold up to the heat and the amount of water the plants need here. Along with the media change I adopted Ray's protocol of K-lite, KelpMax and Inocucor, set up my spare RO unit to provide pure water and added a swamp cooler to my greenhouse. Too many changes to isolate any one factor as a "miracle", but thet have resulted in the absolute best growth I've ever seen in my 25+ years of growing orchids.View attachment 15431
> View attachment 15432



Tony, great picture, you have a nice setup, kudos!

Question, roughly how frequently do you water? Are you the type of person who tends to over water (likes to water frequently) or the type that under waters (periodically forgets)? 

I see in the picture most plants are not sitting in a water collection tray, so I'm curious how quickly they dry out.


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## Tony (May 18, 2019)

I had a tendency to underwater before, both out of habit from growing epiphytes and also because bark and other organics turn into goop very quickly in our summer heat. Now that I've switched over to inorganics I water 3-5× weekly depending on weather. The rockwool holds enough moisture that I could probably get away with less, but it is airy enough that I'm not afraid to keep the plants wetter than I used to be able to and they seem to prefer it.


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## southernbelle (May 19, 2019)

Ray said:


> When I experimented with Grodan cubes years ago, it was available in hydrophilic and hydrophobic versions, so you were able to blend them in your preferred ratio. Apparently that's no longer the case.


Yes, you are right. Only one type seems to be available. And these appear to be hydrophilic as after a week they are just beginning to dry on top. This could be a problem.


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## Tony (May 19, 2019)

southernbelle said:


> Yes, you are right. Only one type seems to be available. And these appear to be hydrophilic as after a week they are just beginning to dry on top. This could be a problem.



Maybe a problem for things that want to dry out like Cattleya, but not for moisture lovers. I have Paphs, Phrags, Brassia, Phals, and Catasetum alliance plants all thriving in it, as well as some non-orchids like Hoya and epiphytic cacti.


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## southernbelle (May 20, 2019)

Tony said:


> Maybe a problem for things that want to dry out like Cattleya, but not for moisture lovers. I have Paphs, Phrags, Brassia, Phals, and Catasetum alliance plants all thriving in it, as well as some non-orchids like Hoya and epiphytic cacti.


What do you mix with it and what percentage?


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## Tony (May 20, 2019)

southernbelle said:


> What do you mix with it and what percentage?



Perlite or LECA depending on pot size, roughly 50/50.


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## Ray (May 21, 2019)

All of my slippers are in S/H culture with LECA.


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## Guldal (May 21, 2019)

From the recent thread on my vigorously growing P. druryi:


Guldal said:


> I grow [all] my paphs in a non-organic medium, Greenmix, mainly consisting of rockwool (diabas), perlite and lignite, i.e. both waterabsorbing and waterrepellent material.
> When properly used, in a short while a nice layer of moss will form on top of the medium... the medium shouldn't be allowed to dry out completely, but the waterrepellent elements should allow for air and some dryness for the roots...
> Our local mastergrower, mr. Hans Christiansen from Orchidégartneriet in Fredensborg, swears to it, some people at my local orchid society seems to hate it... Actually, it appears to me, that the question of growth media is the thing most likely to bring on something akin to religious war among orchid growers!
> In this, parallel to so many other aspects of life, my own rather agnostic maxim would be: choose the growth media(s) you feel comfortable with and get to know it real well, learn from your errors, and don't change what works well! Or maybe it might be appropiate to quote St. Paul in this instance: "...test everything; hold fast what is good" (1. Thess. 5:21)
> Kind regards, Jens


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## Brabantia (May 23, 2019)

Interesting discution! Have you compared shreded synthetic foam like the one used in cushion with rockwood? What is exactly LECA and is this material available in Europa. If not is it existing an equivalent in Europa?


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## Ray (May 23, 2019)

Brabantia said:


> Interesting discution! Have you compared shreded synthetic foam like the one used in cushion with rockwood? What is exactly LECA and is this material available in Europa. If not is it existing an equivalent in Europa?


LECA is Lightweight Expanded Clay Aggregate, and it was developed in Europe for use as an aggregate in lightweight concrete, allowing concrete building to be constructed taller. It was later co-opted for hydroponic growing.

Atami's B'cuzz Hydro-Rokz is probably the best one out there, as it was reengineered specifically with hydroponics in mind.


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## Linus_Cello (May 23, 2019)

Ray said:


> LECA is Lightweight Expanded Clay Aggregate, and it was developed in Europe for use as an aggregate in lightweight concrete, allowing concrete building to be constructed taller. It was later co-opted for hydroponic growing.
> 
> Atami's B'cuzz Hydro-Rokz is probably the best one out there, as it was reengineered specifically with hydroponics in mind.



Is Atamai available in the US? It appears to be only Europe? https://www.atami.com/en_gb/hydro-rokz-8-16-mm

Do you get it from CA?
https://shop.sparetimesupply.com/products/b-cuzz-hydro-rokz--br-45-lt-5948.html


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## Ray (May 23, 2019)

I don't get it at all, any longer. I just use Hydroton from my nearest shop.

Before ATAMI sold the Hydro-Rokz brand, they repackaged it for me under the "PrimeAgra" name. Back then I imported 40' containers of it periodically from Europe, but later they had an agent in Canada that maintained inventory, so I cut back to buying a few pallets at a time from them.

A few years later, Atami set up an agency in the Caribbean somewhere, so I did business with them, but they have not been particularly aggressive about marketing the stuff in the US, so it's really hard to find.


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## spujr (May 24, 2019)

Ray said:


> I don't get it at all, any longer. I just use Hydroton from my nearest shop.
> 
> Before ATAMI sold the Hydro-Rokz brand, they repackaged it for me under the "PrimeAgra" name. Back then I imported 40' containers of it periodically from Europe, but later they had an agent in Canada that maintained inventory, so I cut back to buying a few pallets at a time from them.
> 
> A few years later, Atami set up an agency in the Caribbean somewhere, so I did business with them, but they have not been particularly aggressive about marketing the stuff in the US, so it's really hard to find.



You know of a vendor in US where you can buy smaller quantities?


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## Ray (May 25, 2019)

No.


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## Teresa Koncolor (Sep 16, 2019)

ehanes7612 said:


> I find a mix with at least 50% rockwool to be more forgiving if you forget to water. I probably use a 50/50 perlite /rockwool mix, although I have started to reintroduce some large bark chunks (about 10 percent) because I cant find large perlite chunks...small grade perlite clumping seems to cause concentration zones that affect water retention, ...the bark helps to break it up as the perlite moves around and settles with each watering




I got something called Growstone recently which feels and looks like big perlite pieces.


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## NYEric (Sep 17, 2019)

Yes, but not in the bottom of pots, only on the top with perlite and moss.


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## southernbelle (Sep 18, 2019)

Teresa Koncolor said:


> I got something called Growstone recently which feels and looks like big perlite pieces.


 I use both the GS-1 and GS-2 sizes of Growstone (which is an expanded glass product) instead of large perlite. I like it because it does not crush or breakdown. However, it has been discontinued and is no longer readily available. I hope they bring it back.


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## Phred (Sep 18, 2019)

I haven’t grown anything in rock wool myself but spent the day with the late Azhar Mustafa of A&P Orchids in Swansea Massachusetts. He grew everything in a rock wool based medium. This product also contains what he called hydroponic styrene and perlite. He had 10’s of thousands of Paphs, Phrags, and Cymbidium thriving in the mix he manufactured and sold as Infini-Mix. His family is still running A&P Orchids and still sells his mix... attached are photo’s of the products.


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## SouthPark (Sep 18, 2019)

Tony said:


> Maybe a problem for things that want to dry out like Cattleya, but not for moisture lovers. I have Paphs, Phrags, Brassia, Phals, and Catasetum alliance plants all thriving in it, as well as some non-orchids like Hoya and epiphytic cacti.



The Cattleya orchids probably don't actually require roots drying out in terms of their water tolerating capabilities. The problem occurs if the water around the 'regular' roots is allowed to stagnate ----- lodged there for relatively long periods of time. The 'regular' roots require enough oxygen in the water to stay alive. Otherwise, parts of the roots die, and rot etc. So both growing media and method of watering and air-circulation can be important (apart from other things) for the orchid's health.

But then there are the 'non-regular' roots, which the orchid may produce (when they adapt) to handle being under-water permanently - the roots and base of plant that is - underwater. The roots either adapt (or die), or they actually grow other roots that aren't quite the same as regular roots. These are those roots seen growing in those glass containers filled with water. As long as the person is somehow able to keep things in that water under control (ie. prevent algae and unwanted things from growing and dying and putting a spanner in the works of the controlled 'system', and also provide a certain amount of fertiliser every once in a while - while keeping the water environment under control), then the Cattleya (and those other plants people grow with roots dunked in water) can just keep growing.

As to whether or not those non-regular roots can stay alive under-water indefinitely, I don't know whether these still require the 'still' (motionless) water to be adequately oxyenated - or not. Or whether the growers swap out old water for new water every once in a while.

I'm not a fan of keeping the orchid roots and stem etc dunked in water - with some leaves taking some weight of the plant along the pot rim. Too fiddly to control the system maybe. And that sort of setup (orchid dunked in glass container) looks somewhat ridiculous. Whatever works for those growers is fine I guess.

Also ----- interesting situation about 'moisture lovers'. At the moment, I'm not entirely sure that all paphs require their roots to stay moist. They probably can handle some drying...... or at least some of them, or ones that have adapted.

I have two paphs growing excellently in volcanic rock alone - for about a year or so now. No other media in there. At the moment, it just appears that these paphs don't get any issue with a dry state. I haven't gone for relatively long periods in dry-state though. These particular plants are beyond the juvenile stage though. I don't know what would happen if the same condition were to be applied to baby or relatively small seedling or cloneling orchids ----- maybe not a good idea for small plants that aren't big enough or well established. Not sure. But I can certainly go ahead later to see what happens ----- such as grow small plants in suitably small diameter volcanic rock media.

I also have an Oncidium Twinkle growing in 100% volcanic rock - for about a year too. That one has not only flowered, but also two new growths coming out of it, and the spike is getting its second wave of flowers developing at this time. The media and roots in this orchid's pot does get dry by the next day.

About usage of 'rock wool' .... opening post ..... if one has spare plants to try on, then might as well give it a try ---- for a few plants. But not try it on the rare/expensive ones of course. And as soon as something doesn't look right ----- then definitely intervene right away.

Question --- is there supposed to be some health concerns with rock wool?


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## terryros (Sep 18, 2019)

Orchid roots need oxygen to stay alive and function. Oxygen is not transported to the roots from the leaves, so it must be available in the root zone. It is not water that kills orchid roots but lack of oxygen. The amount of air space in the potting media probably mostly determines the availability of oxygen to the roots, but pot design, water source, and method of watering probably play a role. I am five months in to a trial of growing everything (Phrags, Paphs, Catts, Miltonniopsis, Phals) in pure Growstone (smaller size for smaller pots). I am cautiously optimistic. I think large chunks of rock wool could leave enough air space in a pot, but would worry about rock wool completed compacted around roots.


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## Teresa Koncolor (Sep 19, 2019)

southernbelle said:


> I use both the GS-1 and GS-2 sizes of Growstone (which is an expanded glass product) instead of large perlite. I like it because it does not crush or breakdown. However, it has been discontinued and is no longer readily available. I hope they bring it back.


I ordered a bag online, the larger one. I didn't realise it had been discontinued. I got it with similar size Coco pieces that came in a huge bag. Half and half make a stable moisture, airy mix I've just started using but not on paphs, but lithophyte/terrestrial types like zygopetalum.


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## Stone (Sep 19, 2019)

terryros said:


> , but would worry about rock wool completed compacted around roots.




http://www.orchid.or.jp/orchid/people/tanaka/cult/Brachy/enBrachy.html


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## SouthPark (Sep 20, 2019)

terryros said:


> Orchid roots need oxygen to stay alive and function. Oxygen is not transported to the roots from the leaves, so it must be available in the root zone. It is not water that kills orchid roots but lack of oxygen.



Thanks terry. For those people growing plants in 'still' water ..... with roots in water that just sits there (eg. those people doing the 'full water culture' thing) ------ is that a case where the plant can eventually run into issues if the concentration of free oxygen becomes too low? I'm suspecting that the FWC group probably change their water every once in a while.

I also think that the roots that orchids grow when their stem gets submerged have some other kind of feature that allows them to handle being under-water. I think regular roots becoming submerged actually don't make it (ie. they die). Not sure what the mechanisms are for roots that appear to grow nicely under water. It would/will be super interesting to understand the differences between regular roots and the other ones that have adapted to being kept underwater all of the time.

I agree with Ray's view/hunch he mentioned somewhere - that the roots that get generated by orchids for underwater growth are something different from regular roots. Maybe they look the same, but something is different about them.


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## terryros (Sep 20, 2019)

I did a bunch of reading about plant roots and two facts stood out for all plants. First, oxygen is not transported from leaves to the rest of the plant. The leaves are not the equivalent of our lungs and there is no circulation of oxygen down through the plant. Second, every tissue in the plant needs oxygen or it dies. .Therefore, the roots that are completely submerged in water are getting oxygen from the water until there isn’t any. Since air can constantly diffuse into a volume of water in a container, that must be the source of any ongoing oxygen. Roots that can accommodate to low oxygen water must have a lower metabolic rate, and probably lower function.


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## cpmaniac (Sep 20, 2019)

This is a very interesting discussion. I'm going to take the plunge and try a grow cube/coarse perlite mix for my Phrags and maybe some Paphs.


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## SouthPark (Sep 20, 2019)

terryros said:


> Since air can constantly diffuse into a volume of water in a container, that must be the source of any ongoing oxygen. Roots that can accommodate to low oxygen water must have a lower metabolic rate, and probably lower function.





terryros said:


> the roots that are completely submerged in water are getting oxygen from the water until there isn’t any.



Thanks for sharing that important and most excellent knowledge Terry. This really clears up a lot of things. Important things.


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## myxodex (Sep 21, 2019)

Ray said:


> LECA is Lightweight Expanded Clay Aggregate, and it was developed in Europe for use as an aggregate in lightweight concrete, allowing concrete building to be constructed taller. It was later co-opted for hydroponic growing.
> 
> Atami's B'cuzz Hydro-Rokz is probably the best one out there, as it was reengineered specifically with hydroponics in mind.



The poor quality LECA I have does not hold any water at all and in fact quite a lot of the pellets have an annoying habit of floating in water. The only info I have about Atami B'cuzz Hydro-Rokz suggests that at least some water is taken up into the core of the pellets, can you confirm this ? Also can you remember the approximate average diameter ?


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## monocotman (Sep 21, 2019)

Here are a couple of photos of my plants growing in Rockwool, all are besseae type hybrids, none are long petalled. They are growing in grodan minicubes bought from eBay. I also use larger cubes, also from eBay for the largest pots. The cubes are used straight from the bag. No special treatments. I use rain water exclusively and fertilise with half rate rain mix every watering. The plants sit is a bit of water year round. I do not flush. It very easy and straight forward. The larger plants go out onto the patio for the summer and receive full sun for about half the day. The rest of the time they are all up against a west facing window in the kitchen diner.


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## Ray (Sep 21, 2019)

myxodex said:


> The poor quality LECA I have does not hold any water at all and in fact quite a lot of the pellets have an annoying habit of floating in water. The only info I have about Atami B'cuzz Hydro-Rokz suggests that at least some water is taken up into the core of the pellets, can you confirm this ? Also can you remember the approximate average diameter ?


In reverse order:

The standard size for most LECA brands is 8-16 mm and that's about right for Hydro-Rokz. When I imported 40' shipping containers of it, it was graded at 10-16 at my request.

Yes, it absorbed water very well. After selling off all my plants before moving, there were a few ratty-looking ones that were destined for the dump. It was a good six weeks before the guy buying the greenhouse came to disassemble it and I didn't go out there once to water. Those in the LECA showed no signs of dehydration whatsoever, because there was enough moisture stored in the LECA to keep them going.

That said, most brands of LECA will do the same, given time to soak. I recently prepare some some Hydroton, and about 20% floated initially, but after a day, most had sunk.


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## Brabantia (Sep 25, 2019)

To Monocotman
Strange that you have no algae growing on your pots walls. When I use clear pots I put these in black or brown pot. Since how long have your plants been in these pots with rockwool ?


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## Silverwhisp (Sep 25, 2019)

Ray said:


> In reverse order:
> 
> The standard size for most LECA brands is 8-16 mm and that's about right for Hydro-Rokz. When I imported 40' shipping containers of it, it was graded at 10-16 at my request.
> 
> ...


After soaking the original Hydroton brand for several days, only 20% have sunk. It was first rinsed, then boiled 5 minutes. Is there something I’m missing?


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## monocotman (Sep 25, 2019)

Brabanita,
many of these plants have recently been repotted into new clear pots, I've just bought a batch. so no algal growth yet. I plan to cover the pots with oven foil to keep out the light but allow me to occasionally look at root development,
David


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## Ray (Sep 25, 2019)

Silverwhisp said:


> After soaking the original Hydroton brand for several days, only 20% have sunk. It was first rinsed, then boiled 5 minutes. Is there something I’m missing?


Why boil it?

I'm not suggesting that boiling led to more trapped air - it might, but I really have no idea about that - but considering it has been fired at a very high temperature, it's probably sterile right out of the bag.

After rinsing, mine just say in water.


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## Silverwhisp (Sep 25, 2019)

Okay. Thanks, Ray. Easy enough to let them just stay in water.


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## Sky7Bear (Sep 28, 2019)

I've been out of town, so waited to respond on the computer rather than the phone or tablet. Good discussion.

To the person growing in Growstone, how is that going? I'm sorry that it isn't made anymore, but not a surprise. I have some in my potting shed. Ray, perhaps you can shed some light on this. It was my understanding that you had tried this, and found it too alkaline. However, I've wondered if for Paphs that grow on limestone in nature if that would be an advantage rather than a disadvantage. Any comments?

I'd like to know a LOT more about orchid roots than I do now, as I believe healthy roots are the most important key to good orchid growing, and that most of us don't understand how epiphytic roots work very well, the morphology and anatomy, particularly as it relates to velamen. Does anyone (terryros?) have any recommended reading, particularly that is scientifically informed. I'd like to know if anyone has actually experimented with the notion that the roots (velamen?) develop differently in very wet media or water than they do in other environments, and when that causes difficulty when moving into a dramatically different medium. For example, I have purchased some Phals from Norman's in the past. They are always in plastic in moss. If I leave them in that, the roots tend to rot. If I move the plant and moss into a clay pot, they do fine, but the roots mostly grow next to the moss, and the center of the ball has no roots. Wet plus air? But I can also move them into what I call dry semi-hydro (very little reservoir) and they also do fine growing in what is mostly a damp to dry medium with humidity. I suspect this is not dissimilar to what Alan Koch does at Gold Country with Catts--moss (usually in plastic, as it's much easier to ship), but only in the top of the pot, with air beneath.

And how does air get to the roots (or at least the velamen)? Is it mostly through water, or do they need "real air" too? Some genera are believed to prefer a wet/dry cycle (including at least some of the CAM plants that are almost succulent in nature) but can also develop "water tolerant" roots? I have also seen roots have part of the velamen literally rot away while the living root continue to grow. In fact, when I repot, I tend to strip off rotten velamen and not worry about the actual stringy root very much--green is probably still alive, brown can still anchor the plant even if dead and doesn't seem to add that much "rot" at the base.

I tried A & P's Infini-Mix when I still lived in Seattle and another grower there seemed to use it quite successfully. He said it dried out quickly. Mine never did, and I had rotten roots. I have a bit left, and may try it again, but again, better in plastic or clay? So many variables, and yet healthy roots are essential. Well, probably enough for now.

One more thing. Alan Koch says that orchid roots have stomata, which is, I believe, the way plants take up oxygen. He did not say if this was the root itself or the valamen, but some mechanism like this would be required for the roots to breathe. Only open at certain times of day? I'd love to see some scientifically informed literature on this. He also said that they photosynthesize. Again, true? If so, cutting off light to the roots might not be a good thing. After all, growing orchids in pots is not natural, and their adaptations might be contrary to what we are doing to them for the sake of convenience.


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## Teresa Koncolor (Oct 3, 2019)

Sky7Bear said:


> I've been out of town, so waited to respond on the computer rather than the phone or tablet. Good discussion.
> 
> To the person growing in Growstone, how is that going? I'm sorry that it isn't made anymore, but not a surprise. I have some in my potting shed. Ray, perhaps you can shed some light on this. It was my understanding that you had tried this, and found it too alkaline. However, I've wondered if for Paphs that grow on limestone in nature if that would be an advantage rather than a disadvantage. Any comments?
> 
> ...


My experience with growstone is too short duration to form an opinion. I like using it with something equal size that hold water like the Coco croutons. I like that they are from renewable resources. I use gravel, pebbles, charcoal, lava rocks also as inerts, non deteriorating, but not alone except for epiphytes. I think of paphs as terrestrial/lithophyte of a wet region and I have mine in aquatic plant pot in a finer size mix with orchiatta bark. The seedlings in pure bark. 
I'm very new avid orchid grower


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## monocotman (Oct 3, 2019)

This issue of root adaptation to different environments is very interesting. They certainly do not like to suddenly move from one environment to another once they have developed. It would be great if someone could look at this and work out what is going on developmentally.
I have another observation on roots to add to the mix.
It is possible for roots to adapt to another environment if this is done slowly.
Keith Davis is a premier cattleya grower in the USA and he has a technique for adapting air grown roots to bark in pots.
He explained this on one of the YouTube talks from one of the cattleya symposiums.
We all know that when catts overgrow the edges of their pots, they can produce a whole mass of aerial roots from the lead growth.
If the plant is repotted and these are just planted in a pot of bark they generally die. A big loss for the plant.
However if the plant is placed in the replacement pot and bark is added just a little at a time over the course of a few weeks then the roots have time to adapt and they do not die. A big plus for the plant!
David


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