# Natural growing; why do we repot so frequently?



## Bjorn (Feb 4, 2011)

Some 12-13 years ago I decided to place my 5-6 Paph henryanums and the collection of micranthums I had at that time, into some plastic containers originally used for mushrooms; approx 20x30x15cm. The reasoning was at least two-fold, the micranthums was always struggling with where to place the notorious runners they tended to end up everywhere- out of the bottom of the pots is one location. Regarding the henryanums, I was looking for an alternative to the regular potting.
Ok, they were placed in a compost with plenty of dolomite sand, perlite and small balls of expanded clay together with bark.
For various reasons, my interest in orchids faded and the plants was under less than optimum care for some 10-11 years. 
Then a couple of years ago, I decided to tidy up, and cleared away the weeds; yes they were full of oxalis, the seeds are still sprouting continously as you might see in one of the pictures. During these years, the plants, particulaly the micranthums multiplied and today the originally five plants or so have spread ito the mat of between 30 and 50 growths seen to the left in this picture. Flowering has been consistent, but not massive, today there are 8 buds coming.


 
The henyanums did not that well, and after these 10 years perhaps two out of 6 had died. But they have bloomed regularly all the time. When the oxalis was cleared, the remaining 4 plants rewarded me with some flowers, and after a year with more. We have now come to fall 2010 and the plants produced 10 flowers. This picture gives an overview of that planting.



 

As you may have noticed there is quite a bit of moss around and some seedlings of adianthum as well. Maintaining a healthy population of moss is an indicator of healthy conditions in the soil/pot. Too much fertilizer or too low humidity kills moss right off. Soft water may also be a prerequisite in this connection.
Last year while weeding, I noticed that there was more plantlets than there should be. Incidentially I thought that perhaps henryanum could produce runners like the micranthums did and I found this very interesting. The reason for this assumption was that a little digging showed an intimate connection between roots of the "motherplant" and these "satelites".
As we know that henryanum does not produce runners it was then thought that it could have been seedlings from a chance pollination during the "time of neglect". This suggestion proved to be true as discovered by some more careful digging showing that there was an intimate contact between the roots but as separate entities. Most likely the mycorrhizae necessary for germination and growth of the seedlings is found at the right concentration close to the roots of the "motherplants". Below is one of these seedlings by chance. 





Somehow, I think I remember that there was a chance pollination some 3-4years ago, the guilty was probably a common fly. This was during a time of great problems with invasions of mice into the greenhouse, a terrible pest that was fought by all means including poison. And well, poison plus mice gives a lot of flies. I eventually managed to seal all openings so now I have got rid of that problem at least...
The seeds must have fallen onto the soil and some of them found favourable conditions and produced seedlings. I believe there must be some 5-6 of them in the planting now.
During the last flowering period I pollinated some of the flowers and will try to replicate this experiment in a controlled way.
A nice story isnt it?
BUT the interesting aspect of this story, the plants are still in the same soil as originally, and I see no reason why I should repot them, based on the vigour of the plants. The status of the container might however soon provoke some kind of repotting, some plastics get extremely brittle after many years exposure to the elements- even if it is in a greenhouse.
It all boils down to the following postulate: 
REPOTTING IS NOT ALWAYS NECESSARY AND CAN BE OMITTED IF CONDITIONS ARE RIGHT.
A corollary of this will then be that need for frequent repotting (like every 18months) is an indication of cultivation practises that are sub-optimal.
Ok I do a lot of repotting, but I try to develop methods to avoid it. Maybe because I am lazy, but I firmly believe that there must be better practises than than the repotting every 18months combined with use of fertiliser and fungicide or whatever. The chemicals are likely to influence the biology of the compost negatively, eg. reduce the population of beneficial organisms like mycorrhizae, and with a system out of biological balance more chemicals are needed.
For Epiphytes, probably the only sustainable way is to mount, for paphs it could be that one needs large containers, who knows. Someone has to try and test these things. The results obviously does not come over night, a sucess can be reported after several years. Is there anyone out there having similar experiences?


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## Shiva (Feb 4, 2011)

I agree that it's best to put them in a pot with a good medium and leave them there as long as possible. I've been repotting in Aussie Gold for paphs and phrags for the last year and intend to leave them in there as long as they grow well. So far so good!


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## Wendelin (Feb 4, 2011)

Bjorn,
thank you for this very interessting report! It seems if the substrat is durable it might be better not to pamper the plants to much.


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## gonewild (Feb 4, 2011)

Nice specimens!

If you have enough media in width and depth and a media that does not deteriorate or a media that gets natural supplements there is no need to repot to keep the plants growing healthy. 

When you ignored the care of the containers and let the weeds grow you gave the maintenance back to Nature. Among other things like insects, the Oxalis grew and helped to maintain the quality of the soil.

Now that you have removed the Oxalis and are once again taking charge of the little garden environment you will probably see different results and some time in the near future feel the need to repot. (that is just what humans do!)

Repotting need only be done when the media has become poor in a container or when there is no more room for root growth. A lot of orchids need to be repotted simply so their size can be controlled to fit in a space.

Back many years ago I grew Cymbidiums as cut flowers and about half of our production was grown in raised beds on the ground. The plants grew far better and produced more flowers than the container grown stock. We had not repotting costs and that was great, plastic pots were a new thing then! The plants grew huge in the ground! But after battling gophers and other pests including Oxalis which was a huge spider mite magnet it became obvious that container grown plants were best. Smaller plants repotted often in containers just works out better in the long run for most plants.


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## W. Beetus (Feb 4, 2011)

I would love for my micranthum eburneum to grow like that! Awesome specimen.


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## Eric Muehlbauer (Feb 4, 2011)

How often were they watered? I think if they got by with minimal watering, the medium would be preserved better.


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## paphioboy (Feb 5, 2011)

Just wonderful..!  Those plants look awesome.. IMHO hirsutissimum would grow better if the substrate contained more rock, based on pictures I have seen of them growing in-situ. I think I might try using large plastic baskets like colanders for better aeration at the sides..


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## Bjorn (Feb 7, 2011)

I have been away for the weekend and notice that some of you have placed comments to my post above. Generally speaking I tend to agree with most comments. Here are my replies/impressions:
Durability of substrate; I tend to believe that the substrate would benefit from mimicing nature as close as possible. This would for most paphs mean rocky material, decaying matter and living moss on top. To avoid acidifying of the substrate, I think that generous additions of limestone/dolomite/oyster shell should be incorporated. In my original mixes I added quite a bit of relatively coarse dolomite(like sugar), which might be part of the success. Although its difficult to find in the current mix, it still seems to be there.
Restraint on watering has not been an issue for those mixes in the pics. Quite the opposite, for many years they stood more or less continously soaked during summer at least. If you look at the micranthum leaves, the older are quite stained with a cover of algae. That algae cover on the leaves has to some extent been so thick that I could peel it of, and surprisinly, the surface revealed below was clean and with excellent colour! I have always had a tendency to overwater, and is still struggling with that tendency.
Water quality is another important factor. My water is a mixture of rainwater and water taken from small creek in a bog on the property, the bog water has some 50ppm dissolved and a pH slightly below 7. 
Fertilizing: I do use mineral fertilizer, although I believe its not optimal. It is added at every watering at approximately 250-300ppm total dissolved salts. This equals to some 30-40ppm N. This seems to give good results. I have tried with higher dosages like 100ppm N with the result of massive moss death.
I use growth of moss and lichens as an indicator for "good ecology" in the mixes.
I agree with Lance that this kind of growing is better suited for small species.Cymbidiums and some others woudls simply be too massive and unmanageable if they were left undivided for a longer time. Pobably you could count a couple of other good reasons as well.:rollhappy:
What I miss in the forum is the ecological approach to orchid growing. After all, orchids grow in the wild don't they? They may not look as tidy, but I am convinced that an approach that replicate nature to some extent is the sustainable way to grow. Not only temperature and water, but also below surface. These results are the first steps to investigate this approach. If we were able to nurture the interactions between fungi and plant, the results would be healthier plants. Anyhow it would be interesting in itself.
For this kind of growing, I imagine that the following points should be paid attention:
1)Living moss on the surface is good, it creates a good environment for the roots. Moss is easily killed by too much salts
2)Try to avoid use of fungicides/algicides etc. (Profylactic) use of it produces fine plants but is not good for life in the compost.
3) Fertiliser- use it at low concentrations
4) Feed the mycorrhizae- the compost should contain a certain fraction of decaying matter, can be added as "mulch" or as Lance suggests - as weeds. I believe that some weeds are ok, but of course it should not get excessive. There are better weeds than oxalis that one simply gets too agressive.:clap:

I am currently experimenting with mixes that contain live mycelium of some unknown fungi, and it seems to be quite sucessful. Both sanderianum and rothschildianum show no adverse effects- quite the opposite, seedlings grow quite nicely and not slower than any other paph I have :wink:
The compost was made by adding 1 part of chopped twigs(rose) "oversumered" in a heap, getting full of mycelium and partly decayed to two parts of Lance Birks "pretty good mix". Some dolomite was also added.
As said, the plants prosper; and to prove that there is life in the compost, I had a small mushroom farm growing from the compost a few weeks ago. Dont ask me what is was.
Bjorn
PS I think baskets are ideal for this growing, I personally grow quite a few of my paphs in small baskets.


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## paphioboy (Feb 7, 2011)

> I am currently experimenting with mixes that contain live mycelium of some unknown fungi, and it seems to be quite sucessful. Both sanderianum and rothschildianum show no adverse effects- quite the opposite, seedlings grow quite nicely and not slower than any other paph I have
> The compost was made by adding 1 part of chopped twigs(rose) "oversumered" in a heap, getting full of mycelium and partly decayed to two parts of Lance Birks "pretty good mix". Some dolomite was also added.



I agree this is good, but you have to be very careful to maintain aeration of the mix especially when the organic matter begins to decay to mush. Different types of fungi grow successively and usually the more harmful ones will start to grow after the organic matter has been broken down to very fine particles (more anaerobic conditions). I almost always get a Rhizoctonia problem after a while when I use composts like these..


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## Eric Muehlbauer (Feb 7, 2011)

Another question...what is the origin of your plants? When I first started growing paphs in the 80's, most species were collected in origin. I actually found these collected plants to be far more vigorous, tolerant, and hardy than the seed grown selected plants that predominate now. For one thing, I found the old clones of micranthum and armeniacum to be very stoloniferous..that's not a trait I see in the newer seed grown plants. I got a henryanum from Topper when it first came on the market. Lasted for years, survived rots, and bloomed at least semi-regularly. I have yet to bloom another henryanum.


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## Rick (Feb 7, 2011)

Your results are similar to what I'm hoping to achieve with the sphag/basket system I started a couple months ago for many of my paphs and phrags. There is plenty of inert media mixed in with the sphagnum (sand, limestone chips, expanded clay balls....) . I expect the sphag to break down, but much will just fall out of the baskets. I also get a certain amount of live moss growing too which may automatically replace some of the dead sphag as it breaks down. The moss presently seems to be stimulatory of root growth, but as root mass expands I will probably increase the percentage of inert media.

http://www.slippertalk.com/forum/showthread.php?t=18566


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## Bjorn (Feb 8, 2011)

Paphioboy; Thank you for the warning.Guess you are right in that the "pretty good mix" with twigs itself is not very durable. The plantings I showed in the pics were not based on such mixes, thay had a large proportion of expanded clay,perlite and similar to maintain aeration and structure even after the breaking down of the organic material (mostly bark). It is probably a prerequisite for "an everlasting" soil that it keeps its aeration well, i.e has a fair proportion of structure building inorganics (could probably be plastics as well?) together with a minor part of organic material.
Eric; The plants in the pics are most likely wild collected. And you are right, the stolons was part of the reason for placing the micranthums in that container. They have stolons some 15-20cm long and it was unmanageable to keep them in a pot. Also they contain "original mycorrhizae" which may explain why the henryanums were able to self-propagate.
I am trying my mixes on "fresh seedlings" as well - if it works, well, time will show As for now I have good results with most varieties. There is one challenge though; emersonii, hangianum and emersonii var. huonglaniae. How can you make these things speed up their growth?
Rick; Exactly, - what we are doing is quite similar. In my recent mixes I have modified the composition to contain a rateher high proportion of inorganic particles, for most calcicolous paphs I add some 50% of crushed dolomite/marble (1-20mm) together with some expanded clay. The drawback is that the pots/baskets get much heavier than normal.
I have good access to various kinds of moss from here I live, and I select the type after its use. Mostly according to structure and durability. Recently, I have found a variety that is much more fibrous than bog-moss and this one seems to work well in the mixes. This one is quite coarse in texture and grows on boulders in the local oak-wood surrounding my house. I grow moss in large open containes as well - just to have it "on hand". I have found that having live moss on the surface is very stimulatory for root growth, particularly those that are coming at surface level. With living moss they grow, without, well they are likely to stop.
Bjorn


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## TyroneGenade (Feb 8, 2011)

I grow a lot of orchids in stone (7mm for mini-Catts to 25 mm for big Catts and Brassia types) and notice a lot of leaf litter beginning to accumulate on top and was thinking: hey! instant fertilizer just like in nature. So far the plants look happy and are growing well. 

If you recall this thread, http://www.slippertalk.com/forum/showthread.php?t=18657&highlight=thaianum, you will see in the last picture the plant is growing in bits of old brick etc... Now I'm thinking lets try this for Paphs? I have collected some bits of brick and have some limestone chips and a bag of leaves to mix in. I will give this a try and see how it goes. I have big Leeanum which need some attention and will be the first guinea pig.

This Leeanum hasn't been repotted in years but flowers regularly. What is more, I do notice a lot of leaf litter among the fronds.


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## Rick (Feb 8, 2011)

"There is one challenge though; emersonii, hangianum and emersonii var. huonglaniae. How can you make these things speed up their growth?"


I only have a very small number of these, so my experience is anecdotal.

But if your parvis in general are doing good with your mix and water, then try a cooler darker spot for the emersonii.

I used to have them in a brighter spot and they would add a growth/loose a growth, and in general grow very slow. I moved them to a darker corner near the cooler, and they took off. Leaves at least 20% larger than for years in the brighter spot.

They also responded very well to my occaisonal spikes of Epsom salts for extra magnesium.

Can you give me more complete water chemistry data for your irrigation water?


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## Eric Muehlbauer (Feb 8, 2011)

Ha! emersonii...The slowness is bad enough...but I'd just like to keep one alive after blooming. As slow as it is, its easier to bloom (for me, at least) than any parvi other than delanatii....but it always dies within a year after bloom.


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## Bjorn (Feb 9, 2011)

Tyrone, is your Leeanum looking like this one? This is an old plant I have had for 15years or so, the last 10 in the same pot. You really cant kill those plants seemingly. Well that not 100% true, I used to have 2.



I tried to repot it the other day, and found out that it was impossible to divide into smalller parts. The structure of the plant was like a cross with (all) the rootscoming from the central part. So I placed it a bit deeper in new medium and hope that it roots from the branches as well. All luck to your experiments, but you might try with something less robust than Leeanum? If a plant that survives harsh conditions survives your experiment, then it really does not tell too much about the experimental conditions, does it? Of cours if it dies, then its another story
Rick; thanks for the advice, any thoughts about light intensity for the emersoniis and hangs? I am currently "over-wintering" mine together with the rest of the north-vietnam/S-E China species at some 7C(44F)min and 20C(68F)max. at around 12000 lux (1200fc) Cooling is not a problem here in Norway this time of year.My irrigation water comes partly from a small creek that runs though a bog (sphagnum) before I take the water from it. This is the major part of the water I use, the remaining is collected rain-water. The "bog-water" gets mixed with the rain water in a tank(plastic, 1400l) located below the floor in my greenhouse. This water is kept at some 20C by the use of a fish-tank heater. Chemical analyses, I do not have, just that conductivity readings indicate approx 50ppmTDS for the bog-water, the rain-water is normally below 10ppmTDS. The bog-water is more or less free of Ca2+ and Mg2+. I do not know what contributes to the conductivity, but fresh from the creek there is a slight "sulphury smell" (a bit like H2S - which is a weak acid and might of course contribute to conductivity:wink. pH is just below 7. The smell disappears in the tank, guess that its vented off or oxidised to sulphate or other non-smelling sulphur compound.
Eric: I have heard that story about emersonii dying after blooming, isnt there a simlar story with kolopakingii as well? Reading your reply it struck me that the Bakers, in their Paph books on armeniacum, writes that unless armeniacum is given a cold rest during winter, it tends to "grow itself to death". Perhaps emersonii needs resting in order to restituate? I believe I have seen posts (was it by "Sanderianum"?) here, indicating that cold and dry winter should make hangianum grow faster. Just a suggestion
Bjorn


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## TyroneGenade (Feb 9, 2011)

Bjorn said:


> Tyrone, is your Leeanum looking like this one? This is an old plant I have had for 15years or so, the last 10 in the same pot. You really cant kill those plants seemingly. Well that not 100% true, I used to have 2.



Yes, mine is similar but the crown has died back a bit. I think I can excise a chunk and then neaten and pot on into a better pot. Or I might do what I did with my insigne which was in rock wool: strip as much of the rock wool away as possible and then repot in a new medium.

You point about only finding out anything if it dies is valid. If Leeanum can't survive in it then nothing can. If it lives, well then we know Leeanum is tough enough and we need to perform a stricter experiment. I'm certainly not going to toss may sanderianum to the wolves just yet.


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## Bjorn (Feb 9, 2011)

No, sanderianums are far too expensive for risky testing. You have to assess risk level yourself based on your local conditions and materials available. The classic guinea pig is of course insigne. Ok we might just realize that this kind of testing takes time
Keep me posted, I always looking for this kind of input.
Bjorn


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## Eric Muehlbauer (Feb 9, 2011)

All my parvi's (except delanatii, which is under lights) get a cool winter rest...dry and cool. My winter temps go into the 40's frequently. Interestingly, my original armeniacum (a collected plant) grew for over 10 years, without blooming. The one year it bloomed was after a fall season that was so warm that none of my other paphs spiked. The bud took 5 months before blooming. It died the following year.


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## Bjorn (Feb 10, 2011)

I must confess that I had a similar story with armeniacum some 15 years ago. It came together with the micranthums. blooming and then dead after half a year or so. I attributed it to bad culture, it was in a pot. Possibly, it takes basket culture for good growing? Have not had armeniacum since then until I bought two of them half a year ago. They are in a basket, and one has a bloom so lets see if it survives.


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## Leo Schordje (Feb 10, 2011)

I have a number of parvi's, the "bloom and die" phenomena is real, but it is avoidable. For me one cause of "death after bloom" is that while it is in bloom, I take the plant out of the growing area, take photos, show it around, take it to shows or judging. During this period, sometimes I forget to keep a close eye on the plant, and it gets too dry, or too cold, or too hot. I have killed a few plants just by mishandling them while they were in bloom. Dry the roots out hard, new root tips die, providing a site for pathogens to infect the plant, fungal or bacterial rots.

Another possilble cause of "death after bloom" is that the plant was weak going into bloom. For my parvi's, if the plant is a weak single growth plant, I routinely cut the flower bud off as soon as it is high enough out of the leaves to do so without damaging the crown of the plant. The sooner you remove the flower bud the more energy the plant puts into making the next growth. I know this is a horrible thought to most people, but if the plant can not be replaced, as is the case with collected material, you should really be concerned more with getting the plant up to size rather than seeing what the flowers look like. Seed propagated plants and hybrids, I do let bloom, because they can be replaced. I have bloomed and rebloomed at least 10 Paph emersonii (I have about 16 of them) and have only lost 4 of the original 20 I bought. Paph emersonii & micranthum are the species that forced me to start the flower bud pruning on single growth plants. 

Those are my thoughts, hope this idea helps


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## Rick (Feb 10, 2011)

Leo brings up an old debate on whether or not plants bloom only when in optimal health or plants bloom in a last ditch effort to propogate because optimal health conditions are not available.

(Both conditions may also be true).

Xavier took some soil pH readings around wild clumps of armeniacum and found that the pH near the center of the clump (of past bloomed growths) was lower than the pH around the new (unbloomed) growths where the stolons had pushed out too.

This suggests to me that some type of nutrient depletion or unavailability is going on around old bloomed growths, while stolons are actively "seeking" or passively "migrating" into nutrient available systems.

Logic to me suggests that if cutting a spike to "save energy" for more vegetative growth works in the long term, then either a key (or general) nutrients must be limiting. 

This could be caused by a low pH environment as well as too much or not enough fertilizer.

In the case of the paph species growing on limestone / dolomitic cliffs, I would suspect that the pH environment is probably much more constant than in bark moss or CHC potting mixes in pots. Several of us debated an article in Orchids from several years ago about the use of lime in potting mixes being neccessary. The focus of the article was actually on Calcium, but I noticed pretty quick that the pH of unsupplemented bark mix dropped to very low levels over the coarse of the year, while pH held up pretty well with even a small amount of lime. If I remember the low pH plants grew very poorly in comparison but they may have made it to blooming anyway.

Not only is the pH fairly constant, but there should be a small constant availabilty of Ca, Mg, and PO4 coming off of most limestone based substrates.

When you look at the minneral content of plant leaves, there is typcially a pretty close ratio (moles or molecules) of Ca to Mg. However Ca once in a plant is pretty much there all the time. Mg is used in chlorophyl which depending on light and temp be a more "used up" commodity for plants, and may be a more limiting growth factor.

Bio availability of Ca and Mg is highly variable based pH competition between the two ions themselves, and the amount of other metals such as iron and zinc.

So going back to the emersonii/ hangianum issue, I think its a good strategy to use as much inert material in the mix that will still alow a final pH with irrigation water to stay around 6.0 - 6.5, and periodically spike with epsom salts during periods of faster growth. Most waters that people have for tap water already have 2-3X more calcium than magnesium. And then if you amend your potting mix with lime or oyster shell, you will push the ratio of Ca to Mg up even more.
Dolomitic lime can have a better ratio of Ca to Mg, but it is highly variable by source. So the periodic dose of Epsom salts should just bring the Ca to Mg in balance.


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## Bjorn (Feb 11, 2011)

Anyone having any info on the chemistry of the limestone on which hangianum and emersonii is found? Is it lime or is it dolomite? 
When I use dolomite in my mixes, its as dolomite, i.e. stoichometric dolomite with equal amounts of Ca and Mg (molar). This is also the stuff I added to the old micranthum planting in the picture at the beginning of this thread. Plenty of it. Perhaps as much as 1 part out of 5 was added as coarse dolomite (a bit like rather coarse sugar). So, at least that one had acess to plenty of Mg and Ca and the pH has probably been constant all these years.
One thing that I have noted is the reluctancy of many paph growers to incorporate plenty of limestone(dolomite) or oyster grit into the compot. Some of it is probably inspired by the warning in the books of the Bakers and Braem having warnings against putting limestone into the mix; allegedly because cold water dissolves limestone and the liberated calcium then would poison the plants. How can one imagine that plants growing directly on limestone (e.g. hangianum or helenae and most other parvis occasionally do) should survive the winter? Because it does get pretty cold there, almost down to freezing. And ok, even if it is not raining much, the plants are supplied by, amongst other sourses, seepage water, that according to this cold water theory should be poisonous for the plants.
Well, the idea about cold water dissolving limestone is not all wrong, actually its the dissolved CO2 in the water that dissolves the limestone, and cold water holds more CO2 than warm water. BUT, this also happens in nature, and in soil and the plants still survive.
In in a recent thread by Paphioboy on this forum http://www.slippertalk.com/forum/showthread.php?t=19262
he gave this link which is a link which includes Paphiopedilums in Laos with cultural recommendations: 
http://www.orchisasia.org/especes/p/paphir/paphir_en.html
As a matter of fact, they recommend a mix containing 1 out of 4 parts of limestone.
By having cupious amounts of limestone(dolomite) in the mix, at least the pH (and phosphorous supply?) should be stabilised and also the supply of Ca and Mg(if dolomite is used).
Water is of course important in this connection, and while I do not have any experience using "hard" water, I think that rainwater or equivalent is the best approach after all. 
Btw. there is one negative aspect about putting too much limestone into your mix - the pots get d... heavy.
Bjorn


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## paworsport (Feb 11, 2011)

I have an old malipoense bought in 1990 form a nursery closed now in France. The plant was obviously not a selected but direct import. The plant is vigourous, flowers every 18 month but has not the habit to make stolon : only one new growth etc...


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## Rick (Feb 11, 2011)

Averyanov describes a qualitative difference between the hard crystaline limestone that (I think) emersonii grows on and the soft, stratified limestone that (I think) hangianum grows on in Vietnam. Neither is listed as "dolomite" and mineral content is also not mentioned.

From looking through some geological sources, Dolomitic limestones are very common, and a special yellow dolomite is quarried in Vietnam. 

The % amounts of Ca vs Mg in limestones and dolomites is more like a continuum rather than discreet forms, and the cutoffs are somewhat arbitrary. It's almost as bad as slipper taxonomyoke:oke:

Dolomites I believe tend to be softer and easier to disolve than high calcium limestones.


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## Bjorn (Feb 14, 2011)

Averyanov only says something about Mg in soil when he describes alkaline soils. There he states that they are rich in Mg. The deposits of thse soils are according to the map adjacent(just south) to the limestone where hangs and emersoniis ++ are found. Can we , based on this, suppose that the limestone is rich in Mg?
Btw. Its impossible to see any difference between crystalline Dolomite and Limestone. Both looks like marble - at least the stuff I have is white, dense and with crystallites of perhaps 1mm, i.e. fairly coarse textures and probably slow to dissolve.


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## TyroneGenade (Feb 14, 2011)

Hi,

The Leeanum experiment is under way. I took the plant out of it pot and was surprised to see a miserable rotting root system on a healthy plant. There were lots of new roots coming so I repotted as well in bark with some broken bricks and river sand and then into a smaller pot! (Not the direction I was hoping to go.) I cut off one piece of 3 growths which went into a small pot with bricks and leaf litter. As the bricks are alkaline in any case I figured there was no need for limestone. 

So I have 2 experiments on the go... If both die then we know this isn't a way forward. If they thrive, then I can try something more picky about potting conditions.


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## Leo Schordje (Feb 15, 2011)

About limestone, Rick, you are right. I used to work in chemicals for concrete industry. As you said, the chemical properties are on a continuum, there is no bright line between dolomite and limestone. About the hardness, & resistance to weathering, again the full continuum exists. Hardness of all types of limestone (including dolomite) is directly related to the inclusions of impurities, like silica, manganese, iron and other minerals. Dolomites high in manganese and iron can be very hard, as can nearly pure calcium containing limestone if it is high in silica and formed under favorable conditions. The second factor influencing hardness is the formation process, the number of times the parent material has been dissolved and re-crystalized and the pressure and temperature at which this happens. So it is possible to find the full range of hardness for both dolomite and for limestone.


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## tenman (Feb 15, 2011)

I have two reservations about long-term growing without repotting. While it may work in isolated instances, the key fact that must be remembered is that plants in nature are not growing in a limiting plastic pot. The chief problem is that if there are any ingredients in the mix which can break down, they can often clog drainage holes, causing a serious problem and ultimately root death. As well, said breakdown may eliminate the possibility of aeration in the mix itself, also leading to root problems. Lastly, if you look closely, plants in nature are not growing in one location. That is, the plant moves on through time as it grows naturally, leaving the old dead and dying growths in the depleted area as its new gowths inevitably march on to new turf.


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## Rick (Feb 15, 2011)

tenman said:


> I have two reservations about long-term growing without repotting. While it may work in isolated instances, the key fact that must be remembered is that plants in nature are not growing in a limiting plastic pot. The chief problem is that if there are any ingredients in the mix which can break down, they can often clog drainage holes, causing a serious problem and ultimately root death. As well, said breakdown may eliminate the possibility of aeration in the mix itself, also leading to root problems. Lastly, if you look closely, plants in nature are not growing in one location. That is, the plant moves on through time as it grows naturally, leaving the old dead and dying growths in the depleted area as its new gowths inevitably march on to new turf.



Some of the same logic I used to using the slat basket instead of pots. Many of my most successful non slipper orchids are mounted or in baskets that I just top up with fresh moss periodically. Many paphs are cliff dwellers growing a lot like epiphytes with roots totally exposed, so why not treat them more like more other epiphytic orchids?


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## Bjorn (Feb 16, 2011)

Tend to agree with Rick above. If we are to change the growing regime towards more "Natural" growing, one typical move would be to look at the pots. Aeration is probably an important point. When it comes to decay etc. a potting mix based on inorganic "structure builders" like expanded clay, limestone etc. with organic material as supplement and nutrition for the roots could be a starting point. A rough guide for the proportioning of the structure is that monosized material generally packs to approximately 50%. I.e. if Leca is poured into a container, then approximately 50% of the occupied volume is Leca, the rest is voids. These voids can accomodate finer stuff and so on, and astonishing packing densities can be accomplished by careful packing. For orchids we would like to have porosity though, and should therefore leave room for the roots. I would expect that the most serious problem is connected to the size of the plant, particularly for large plants with massive roots. I strongly suspect that after some time an undersized container will be full of roots, some of them die after a time, and if the container is too small, the conditions get stale and the root die-off spreads.
Managing the whole concept (that is growing with a minimum of re-potting) gets much easier with moderatly sized plants.


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## tenman (Feb 16, 2011)

Rick said:


> Some of the same logic I used to using the slat basket instead of pots. Many of my most successful non slipper orchids are mounted or in baskets that I just top up with fresh moss periodically. Many paphs are cliff dwellers growing a lot like epiphytes with roots totally exposed, so why not treat them more like more other epiphytic orchids?



One difficulty in replicating the natural environment is that those cliff-dwellers are subject to almost constant seepage of moisture past and over/under their roots. In culture we are mostly limited to watering in intervals and keeping the substrate moist to allow the constant uptake of water they are used to. Growing Disas in a flowtable simulates their natural environment more accurately than most other methods of growing orchids I have seen. Of course, a paph isn't going to want its roots submerged all the time, either. So perhaps mounting paphs slantwise on a rock with some detritus loosely under/over the roots and then having a drip tube attached to allow for a constant but minimal amount of water (rainwater, of course) to seep down the rock would be close. But what a pain to set up, and then there's the runoff to consider...


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## Rick (Feb 16, 2011)

tenman said:


> One difficulty in replicating the natural environment is that those cliff-dwellers are subject to almost constant seepage of moisture past and over/under their roots. In culture we are mostly limited to watering in intervals and keeping the substrate moist to allow the constant uptake of water they are used to. Growing Disas in a flowtable simulates their natural environment more accurately than most other methods of growing orchids I have seen. Of course, a paph isn't going to want its roots submerged all the time, either. So perhaps mounting paphs slantwise on a rock with some detritus loosely under/over the roots and then having a drip tube attached to allow for a constant but minimal amount of water (rainwater, of course) to seep down the rock would be close. But what a pain to set up, and then there's the runoff to consider...



I tend to over water (something daily), and keep air humidity very high. My present mounted and basket stuff stuff does great, which was another consideration in moving my cliff dwellers to the baskets. 

So far in the first month things are going great. I'm particularly impressed with the growth of some roth seedings so far. My adult stoneis are showing new growth and roots, and I'm seeing new root growth in sanderianum seedlings.

One or two years from now I might be cursing this system, and everything seems to work good for a couple months, but we'll see.


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## cnycharles (Feb 16, 2011)

tenman said:


> .... So perhaps mounting paphs slantwise on a rock with some detritus loosely under/over the roots and then having a drip tube attached to allow for a constant but minimal amount of water (rainwater, of course) to seep down the rock would be close. But what a pain to set up, and then there's the runoff to consider...



if you had a reservoir at the bottom, put a small aquarium pump there and pump the water back up to the top


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## tenman (Feb 16, 2011)

Rick said:


> I tend to over water (something daily), and keep air humidity very high. My present mounted and basket stuff stuff does great, which was another consideration in moving my cliff dwellers to the baskets.
> 
> So far in the first month things are going great. I'm particularly impressed with the growth of some roth seedings so far. My adult stoneis are showing new growth and roots, and I'm seeing new root growth in sanderianum seedlings.
> 
> One or two years from now I might be cursing this system, and everything seems to work good for a couple months, but we'll see.



Keep us posted; it'll be interesting to see how they do. Good luck!



cnycharles said:


> if you had a reservoir at the bottom, put a small aquarium pump there and pump the water back up to the top



Yes, but the water wouldn't be fresh for long, going through the crap around and under the roots. I like the 'drip' idea, but it would be monumentally difficult for a large collection of paphs, and you couldn't share the water between them for fear of spreading things. I know it's risky even with the couple dozen disas I have, but it's the only way I can manage them. I know several folks who have had problems with spreading fungus/bacteria among an entire collection of disas thusly and lost most of them. I think I've reduced the chances of that substantially by switching to straight diatomite as my medium for them, but it still concerns me.


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## Ernie (Feb 17, 2011)

Tenman, ever consider adding a UV sterilizer to your recirculating water? You can find inline and submersible ones on eBay for under $50 (I'd guess a 9 watt unit would work for you).


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## valenzino (Feb 17, 2011)

Remember that in the natural environment plants die daily and only few reach specimen size....the goal of the plant is to produce seeds once.
Growing plants to big size is a human behaviour...
I agree about air in the roots and less repotting possible...
but depends on many different topics.
Exaple,leaf mould growers use to run ...so yearly repotting is better...strap leaves ones...is better to repot less often.
Few Paphs have "underground roots",usually are on the surface and run far away from the plant...very good air qty...
My opinion is best to try "thick net pots" with semy inorganic media and disturb less possible roots while repotting.


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## cnycharles (Feb 17, 2011)

Ernie said:


> Tenman, ever consider adding a UV sterilizer to your recirculating water? You can find inline and submersible ones on eBay for under $50 (I'd guess a 9 watt unit would work for you).



ah, I thought of this, this morning when at work... have supervisor who has had many fish tanks and talks about all the bells and whistles. also some apple cider producers use these systems for sterilization, as well as more greenhouse and nursery producers who must re-use their waste water as they have very strict water use requirements in their states or localities. in central ny there are no use requirements like this since we seem to have a high level of rain and snowfall each year (and plenty of clouds when it's not actively precipitating)


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## Rick (Feb 17, 2011)

valenzino said:


> Remember that in the natural environment plants die daily and only few reach specimen size....the goal of the plant is to produce seeds once.
> Growing plants to big size is a human behaviour...



I would agree if you are talking about seedlings primarily.

There are many species of plants and animals that have not adopted the salmon or octopus model of dieing after their one and only reproductive event. I disagree that slippers are more like annuals and ready to crater after one seed production event (even though I realize that any given growth blooms only once). We seem to see multiple cases where many paphs seem to not want to flower until they have acheived at least a few growths in a pot. In particular I think you have reccomended not dividing roths until multiple growths are achieved. 

I think we've all seen plenty of in-situ pics of huge clumps of many adult slipper species that would suggest that big multigrowth slippers are not strictly a GH (human) phenomena.

Given the low succes rate of polination and seedling survival, at some point in plant age (size), slippers must be pretty durable for years on end to keep from going extinct.


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## Bjorn (Feb 18, 2011)

One comment to the water issue: I have a rather extensive collection of Dendrobiums mounted on bark. Before I got my greenhouse some 15 years ago, I grew them indoors, mounted on a wire-mesh. Because of this and because of extensive travelling I installed a drip-irrigation system on the slabs with a tray to take the excess water. The drip-irrigation worked nicely in combination with occasional misting and the excess water was almost in balance with the evaporation, i.e. I had to empty the collecting tray only occasionally. This shows that it works. It is however most certainly dependent on pure water, rain or R-O or at least "soft" water due to evaporation from the roots. This was for dendrobiums. Now , In the greenhouse, I spray everthing down with a hose, and that is of course much easier.
My paphs grow either in baskets or pots. The baskets are rather large for the size of the plant so commonly its used on small species, often several of them together, like the pics in the first entry of this thread. The soil that I am using looks quite "gravelly" i.e. gravel with organic matter (bark, moss, minced twigs etc. The gravel consist of mostly dolomite and marble, but also perlite, expanded clay and plain sand. Top dressing may be done with decayed leaves, bonemeal etc, but first of all, moss growing on the surface is sought for. This is only happening if the surface is quite moist, so my watering regime might be a bit different from others. I try not to overwater but still keep surface moist - This is to mimic dew. I rarely flush the pots, but every morning the surface is sprayed, and the humidity is kept at 70% and above (70-95%) during daytime, and during night it raises to >95%. After the lights are off, frequently a thin fog fills parts of the greenhouse, but without excess moisture to the plants.
If the moss grows, everything is fine, if it dies off then obviously something is wrong. It could be the fertiliser being too strong, seems as the limit is around 250ppmTDS for healthy moss. Too much moss is not good either so occasionally some might be removed. This is mostly done for small paphs in baskets. Btw. these are not hanging baskets, Just rectangular basket like plastic boxes with ribs on the sides, intended to store things in. Most of the larger paphs are in regular pots, but I am slowly converting them from standard mixes to more long lasting attemts like the one described above.


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