Natural growing; why do we repot so frequently?

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Well-Known Member
Sep 6, 2010
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S. Norway
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:
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:D, 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?
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!
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.
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.
How often were they watered? I think if they got by with minimal watering, the medium would be preserved better.
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..
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.:)
PS I think baskets are ideal for this growing, I personally grow quite a few of my paphs in small baskets.
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.. :(
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.
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.
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.:(
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,, 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.
"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?
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.
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:p
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:D
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.
No, sanderianums are far too expensive for risky testing.:D 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.
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.
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?:confused: 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.:D