'What Orchids Eat', importance of calcium

[Discus]

Originally Posted by Ray

Unfortunately, there are folks who prefer to keep their heads in the sand

At least they'll get plenty of Si in there...

Wow, this topic got heated, I am glad that they still haven't invented that stabbing-people-in-the-face-over-the-internet technology.

One thing people forget is that evolutionary histories mean that you'll get some adaptations to differing nutrient regimes - just like there is no "one true light intensity" "one best medium" "single perfect watering schedule" there is almost certainly never going to be "the one true fertiliser for everything".
Quite how we got on to discussing mangroves here I'm not sure (they're pretty Odd because of all the dealing-with-salt metabolism), and not very closely related to orchids either.
I think it's pretty logical to assume that terrestrial and epiphytic orchids are likely to have quite different nutrient physiologies.
It's also plausible that closely related orchids are likely to share similar requirements.
It's not necessarily logical to assume that only distantly related orchids will share the same requirements "because they're orchids". That's a little bit like saying you can feed a lion on grass, because it's a mammal, and other African mammals, like hippos, eat grass*.
Just as within one species (Homo sapiens, the only one I'm aware of that routinely posts on this board) we find people with differing nutrient requirements, it seems reasonable to expect different plants, particularly in a family as diverse in habitat and growth regimes as the Orchidaceae, to have some different needs.

Long story short, orchids are a big, diverse group. Other than phalaenopsis, I suspect most orchids aren't "commercial" enough to have warranted large scale growth trials of the sort to definitively answer these questions. Phalaenopsis are capable of being cultured at much higher EC (nutrient) concentrations than many others, so, despite them being the best researched, they may not help you that much with more "delicate" plants.

Until such a time as a wealthy benefactor decides to conduct such trials, or someone decides to start culturing delicate species for the mass market and doing the required research, I suspect we'll be left with what orchid growers have relied on for decades - their own experience of their plants in their conditions, and the tips that other fellow "orchidiots" have shared with them. Such tips are usually specific to particular plants, and we should probably start reporting our observations this way (i.e. "my orchids respond in way X to treatment Y" isn't necessarily as helpful as specifying which orchids respond, how long you've been doing this, and whether it constitutes anything stronger than anecdotal evidence or not). I'm pretty sure there exists enough knowledge on this board to design rigorous trials - but someone would have to volunteer the time and space to do them!

This means that as far as I understand it, there isn't any direct, scientific evidence to conclusively prove or disprove the Potassium Hypothesis one way or another, and there won't be anytime soon.

As with all orchid growing advice, feel free to ignore it, or try it out on your own plants. Shouting at each other and grasping at very tangentially related studies isn't going to help anyone grow their plants better, and I don't think it's in the spirit of this forum. Some of these replies have wandered very close to ad hominem attacks, and that's not cool :/

*I realise that these examples are not in the same Family [unlike all orchids], however, taxonomists have tended to "over-split" mammals and birds relative to plants (and many other groups) in the opinion of many systematists. That said, the orchid family is evolutionarily quite young - but they seem to evolve pretty fast. I don't have time right now to look up the relative degrees of evolutionary distance between some herbivorous and carnivorous mammal vs. some orchids, but the info should be out there if anyone is sufficiently bored and has access to such literature. Perhaps a better example might be that you decided to feed a polar bear on bamboo, because you're used to keeping pandas.

---------- Post added at 04:05 PM ---------- Previous post was at 03:55 PM ----------

One final thing to consider - replicating the natural environment precisely isn't always going to result in the best growth. Even though the ancestors of Betta splendens live quite happily in muddy ditches doesn't mean your fishtank at home should be like a muddy ditch.

This also means that although plant X may survive in nutrient regime Y in the wild, it may thrive better (at least in captivity) under something else entirely.

Nature gives us a good starting point, but if we're truly interested in "optimum" nutrition, we'll have to find out what that is somehow. And that is a painstaking process indeed.

Most people are ultimately interested in "good enough" with their plants, but would I suspect welcome the firm, verifiable findings of others on "better" and just love "best"!

---------- Post added at 04:27 PM ---------- Previous post was at 04:05 PM ----------

Originally Posted by Fabian24

Just to quote some paragraphs of a relatively new one:

That paper notes that plants grown with *no* potassium were dead "by May" (you highlight in red in the quote in your post) - I don't think anyone is saying "hey, all potassium must be eliminated", people are saying "lets try less potassium". (Hence K-lite not NO-K)!

Even then, I think we should be somewhat wary of globalising phalaenopsis as "all orchids therefore..." because the majority of my orchids would croak if I gave them 800 uS/cm fertigation, which phalaenopsis are apparently quite happy with. We might also like to consider the possibility that a regime that works well in a tightly controlled greenhouse may not work well in a home, and it may not necessarily work out well in "long term" culture (phalaenopsis are grown as quickly as possible for a market that is, let's face it, primarily bloom and toss).

As I said a bit earlier in this post, we're mostly here to learn; if someone finds that something that flies in the face of conventional wisdom (which, with fertilisers, for the most part concerns terrestrial plants, mostly annuals at that) seems to work for them, I'd say it's worth noting and considering, and following with interest, rather than attacking with extreme vehemence.

Also we wandered extensively off topic from Calcium to Potassium...

[King_of_orchid_growing:)]

Originally Posted by Ray

Philip - I absolutely agree that there are likely a number of different reasons plants just "crap out". As I stated, the theory that potassium buildup might be part of it is merely one.

I do respect your comments, but in this case, by scientific standards, please let's try to refrain from the use of the word "theory", because scientifically speaking - it is not a proven fact as of yet, so it cannot be a theory. A theory has theorems behind them to support the claim and can withstand scrutiny.

If you want to use proper scientific lingo, let's stick to either the words "thesis" or "hypothesis".


By layman's standards, I understand the meaning of the word in context of the situation, but still, it implies that there is support to the claim when it is really what I deem - an inconclusive idea or inconclusive/anecdotal observation.

All I'll say in regards to the subject matter of K+ toxicity is that it's an inconclusive observation and that any observational claims that cannot be put under scrutiny and survive must be deemed anecdotal evidence at best.

Originally Posted by Ray

Fabian's comment about K+ being readily relocated within plants tissues is dead on. That suggest that when fed a low-K diet, the plants should go a long time before there are symptoms of a deficiency. But how long is long enough? My plants are in month 19, and I still keep a close eye on them looking for issues, but I have seen none. There are others that have used this diet regimen on their collections well beyond that, time-wise. To the best of my knowledge, the only negative seen in anyone who has decided to join the experiment was one lady who grows cattleyas outdoors in western Florida. She saw what she interpreted as "premature loss of older leaves" while the rest of the plant carried on quite well. The old leaf loss might be related, and might not. I certainly don't know.

Again, unless there are controls and better ways to observe the phenomena, the results are going to be inconclusive.

Unless you have a lab to work with and controls are set up in the experiment, it will be inconclusive. Being inconclusive evidence is not necessarily wrong evidence, it's just an observation that has not been put to the test (aka scrutiny).

As far as I know, you'd have to be working with electron microscopes or whatever, and ionic tracers and such in order to figure it out for certain. I'm sure you or I, or those involved in your trials do not have the means to carry this out without a huge grant of some sort.

Originally Posted by Ray

I guess the bottom line to me is that there really is no need for folks to get so "uppity" about the conversation.

Each of us has our own reason for participating in these forums. I do so to share my own observations and learnings, and to gain from those of others, because right or wrong, they open us up to more information, and an overall greater understanding of orchid culture. Philip, I view you and many others here to be of a similar bent. Unfortunately, there are folks who prefer to keep their heads in the sand (or elsewhere), and only seem to post in order to tout their own presumed expertise.

Fair enough.

Thank you, btw.

Originally Posted by Discus

At least they'll get plenty of Si in there...

Wow, this topic got heated, I am glad that they still haven't invented that stabbing-people-in-the-face-over-the-internet technology.

Originally Posted by Discus

One thing people forget is that evolutionary histories mean that you'll get some adaptations to differing nutrient regimes - just like there is no "one true light intensity" "one best medium" "single perfect watering schedule" there is almost certainly never going to be "the one true fertiliser for everything".

I'm not arguing this. It is true. However, the common theme in all higher plants are the macronutrients:

N (nitrogen) - P (phosphorous) - K (potassium)

Whatever concentrations they acquire from their environments will vary. But they all use these macronutrients to survive.

And speaking of potassium and higher plants in general, it has been concluded that all higher plants have a significant uptake of K. Since orchids are in the Plant Kingdom, it is applicable to them too, considering that it has been confirmed scientifically that along with many other higher plants they also have fairly large amounts of K present within their tissues in order to function properly.

And this is why most fertilizers will generally contain the nutrients N, P, and K.

Originally Posted by Discus

Quite how we got on to discussing mangroves here I'm not sure (they're pretty Odd because of all the dealing-with-salt metabolism), and not very closely related to orchids either.

The point was that plants in general will not only have passive transport of nutrients in place, but active transport as well.

Originally Posted by Discus

I think it's pretty logical to assume that terrestrial and epiphytic orchids are likely to have quite different nutrient physiologies.
It's also plausible that closely related orchids are likely to share similar requirements.
It's not necessarily logical to assume that only distantly related orchids will share the same requirements "because they're orchids". That's a little bit like saying you can feed a lion on grass, because it's a mammal, and other African mammals, like hippos, eat grass*.
Just as within one species (Homo sapiens, the only one I'm aware of that routinely posts on this board) we find people with differing nutrient requirements, it seems reasonable to expect different plants, particularly in a family as diverse in habitat and growth regimes as the Orchidaceae, to have some different needs.

But you're still not going to run away from the fact that regardless of whether they're terrestrial or epiphytic orchids, they still use N-P-K.

Originally Posted by Discus

Long story short, orchids are a big, diverse group. Other than phalaenopsis, I suspect most orchids aren't "commercial" enough to have warranted large scale growth trials of the sort to definitively answer these questions. Phalaenopsis are capable of being cultured at much higher EC (nutrient) concentrations than many others, so, despite them being the best researched, they may not help you that much with more "delicate" plants.

Phals may be the only one that is of serious commercial interest, but you'll still see common threads amongst other orchids; and I'm sure orchids in general, will share common threads with other higher plants in general with regards to K specifically.

Originally Posted by Discus

Until such a time as a wealthy benefactor decides to conduct such trials, or someone decides to start culturing delicate species for the mass market and doing the required research, I suspect we'll be left with what orchid growers have relied on for decades - their own experience of their plants in their conditions, and the tips that other fellow "orchidiots" have shared with them. Such tips are usually specific to particular plants, and we should probably start reporting our observations this way (i.e. "my orchids respond in way X to treatment Y" isn't necessarily as helpful as specifying which orchids respond, how long you've been doing this, and whether it constitutes anything stronger than anecdotal evidence or not). I'm pretty sure there exists enough knowledge on this board to design rigorous trials - but someone would have to volunteer the time and space to do them!

This means that as far as I understand it, there isn't any direct, scientific evidence to conclusively prove or disprove the Potassium Hypothesis one way or another, and there won't be anytime soon.

Ok, look, I don't consider anybody "orchidiots", let's please leave that out of the picture.

Yes, you're correct about having to expend a lot of time, money, and resources to find out for certain whether this low K/K toxicity claim is conclusively a true assertion.

And, yes, it probably won't happen anytime soon.

But in the meantime, there are other pieces of information that is known regarding this subject matter, and we can't dismiss those either.

Originally Posted by Discus

As with all orchid growing advice, feel free to ignore it, or try it out on your own plants. Shouting at each other and grasping at very tangentially related studies isn't going to help anyone grow their plants better, and I don't think it's in the spirit of this forum. Some of these replies have wandered very close to ad hominem attacks, and that's not cool :/

I have not "shouted" at anyone. I'm merely making my points.

And for every subject matter that I feel is incorrect, I will feel free to poke holes in those arguments provided there are counterarguments that are known to be correct.

Originally Posted by Discus

That said, the orchid family is evolutionarily quite young - but they seem to evolve pretty fast.

??? ???

The orchid family is evolutionarily quite young in respect to which plant group? If you're comparing them to conifers, then yeah, orchids are relatively extremely young, evolutionarily speaking. If you're making a comparison to other Angiosperms, then I do beg to differ on this.

There was at one point in time where scientists have discovered ancient pollinia attached to an ancient bee that was trapped in amber. This fossil pollinia has been dated back to about 80 million years ago - during the late Cretaceous period when Dinosaurs still roamed the Earth!

In other words...

A random Tyrannosaurus rex at one point in time probably saw an orchid in its lifetime!

Here is the article about the bee and the pollen:

First orchid fossil puts showy blooms at some 80 million years old | Harvard Gazette

Originally Posted by Discus

Also we wandered extensively off topic from Calcium to Potassium...

True...

But I think Ca and Mg has ties to K somehow, without taking a class in plant cell biology/physiology, I wouldn't be able to describe what that is. However, I do suspect it has something to do with energy potentials.

[Fabian24]

Originally Posted by Discus

That paper notes that plants grown with *no* potassium were dead "by May" (you highlight in red in the quote in your post) - I don't think anyone is saying "hey, all potassium must be eliminated", people are saying "lets try less potassium". (Hence K-lite not NO-K)!

Even then, I think we should be somewhat wary of globalising phalaenopsis as "all orchids therefore..." because the majority of my orchids would croak if I gave them 800 uS/cm fertigation, which phalaenopsis are apparently quite happy with. We might also like to consider the possibility that a regime that works well in a tightly controlled greenhouse may not work well in a home, and it may not necessarily work out well in "long term" culture (phalaenopsis are grown as quickly as possible for a market that is, let's face it, primarily bloom and toss).

As I said a bit earlier in this post, we're mostly here to learn; if someone finds that something that flies in the face of conventional wisdom (which, with fertilisers, for the most part concerns terrestrial plants, mostly annuals at that) seems to work for them, I'd say it's worth noting and considering, and following with interest, rather than attacking with extreme vehemence.

Also we wandered extensively off topic from Calcium to Potassium...

The purpose of showing what happens when you deprive a spiking Phal of potassium is rather clear.
For 50 to 100 ppm K plants develop leaf yellowing or leaf abscission during flowering.
For 0 ppm K they die.
So, for 20 ppm (which is what low-K formulations provide, assuming you adjust N to the standard 200 ppm), the results should lay in between those 2 cases. Not very encouraging...


When a general claim is made, such as:
Orchids thrive better with a fertilizer that contains a negligible K concentration
A counterexample is all you need to assess the fallacy of that claim.
There is no point in arguing : "Ah! Phals are a special case... "
The claim is no longer valid.

A publication of the College of Tropical Agriculture and Human Resources of the University of Hawaii [1], shows illustrations of plants of Vanda Miss Joaquim with N, P and K deficiencies, being the one with K deficiency the worst looking of the 3.

Is Vanda Miss Joaquim just another “special case”?

Cibes et al. in a gravel culture experiment observed that an increase in either N or K levels resulted in an increase in Vanilla vine growth, with the high-N, high-K level producing the
best growth. [2]

Vanilla? Another “special case”?


It is true that not all orchids are so sensitive regarding K needs.
Cattleya is an example:

Davidson (7) observed that deficiencies of N and P limited growth of Cattleya
more drastically than did K, Ca or Mg in gravel culture and they were more likely to respond to applications of N and/or P. He reasoned that plants lacking an external supply of K are capable of translocating this nutrient from old tissues and re-utilising it to meet most of the growth requirements for K by new tissues. Likewise, Ca and Mg present in old tissues are re-utilised, but to a lesser extent than K.
Small amounts of K, Ca and Mg often present in rooting media or water supplies appeared to satisfy the requirement of these elements for Cattleya. [2]

But if you believe this report is true, why should you put Cattleyas to a negligible K diet, and at the same time claim that they need such an excess of Ca?



Ray,

You say that you didn’t observe any symptoms of K deficiency, despite using less than half the concentration at which K deficiency symptoms are observed in many orchid genera.
I believe you.
But unless you do a controlled trial, you can’t infer that this is the correct K dosing for fertilizing every orchid.
Do you use inert media, so that you can be sure the medium is not providing extra K?
Do you always water with RO, so that you can be sure there is not an extra supply of K in the water?
Even if you are sure that neither your medium nor your water can provide extra K,
what about sodium, so common in water and media?
It is a known fact that sodium can be temporarily used as a susbtitute of K, in case of need.

Plants are able to use Na to substitute for K under K-deficient conditions to lessen the deficiency symptoms (Figdore et al., 1989; Sharma and Singh, 1990). Reverse osmosis water and nutrient salts used in this study contained no Na and that may have contributed to the severe symptoms and death of K-deficient Phalaenopsis [3]
.


Refs.
[1] Tadashi Higaki, Joanne S. Imamura, NPK REQUIREMENTS OF VANDA MISS JOAQUIM ORCHID PLANTS, Research extension series / Hawaii Institute of Tropical Agriculture and Human Resources, Nov. 1987.
[2] HUGH A. POOLE, JOHN G. SEELEY, Nitrogen, Potassium and Magnesium Nutrition of Three Orchid Genera, Journal of the American Society for Horticultural Science, Volume 103, No. 4, July 1978.
[3] Yin-Tung Wang, Potassium Nutrition Affects Phalaenopsis Growth and Flowering, HORTSCIENCE 42(7):1563–1567. (2007)

[Discus]

Sorry - I didn't mean to offend with the term "orchidiots" - it's a common term of endearment in some quarters for those who have been conned by these plants into devoting extravagant amounts of time, energy and resources into tending for their every need, rather than any implied aspersions on their intelligence! I rather like it and apply it to myself at times.

I don't for a moment think that orchids are some magical special case that can suddenly forgo a need for well established macro and micronutrients. (Indeed, I don't think anyone is implying that we need to suddenly say "none of this is required").

I am however open to the possibility that (at least some) groups of epiphytic orchids may well have slightly different requirements for nutrients than terrestrial plants, certainly in terms of magnitude - if not ratio. It's entirely possible that the effects some growers have observed with "low K" formulations are a result of an improvement that would have been equally well addressed by an overall decrease in fertiliser concentration, and not just specifically K.
It's also plausible that epiphytes might be more "active" in their uptake of nutrients (possibly through their fungal partners) than some other plants may be [and this might be particularly so for K] - it makes sense in an environment where essential resources are scarce to make a special effort to get them, whereas active transport when it's naturally flooding in would be counter-productive (from a metabolic cost PoV). I have not studied the literature on this, if there is any (for orchids), but I'm sure the literature on the result of mycorrhizal associations on the nutrient status of conifers and likely crops details this. It may also be worth bearing in mind that the vast majority of cultured orchids lack mycorrhizae and that could affect things (like maybe needing more Ca or Mg, and less K). I would also imagine some enterprising tropical forest science people would have sat down and thought "hmm, epiphytes, from whence their nutrients" and put time, effort and money into working it out, so I guess we could uncover some knowledge here. *But* what happens in nature is only a guideline; the "optimal" nutrient mix may be different to what's "good enough for survival". Again, this points to the need for real, controlled trials if we really want to resolve this. Given the generally slow growth of the group and the general tendency to want to keep them alive for decades or longer, that's quite the trial. I'm not sure you can necessarily measure the overall "happiness" of a plant at the cellular level - I would have thought controlled growth trials would be a better (and likely less tech intensive) demonstration of particular nutrient regimes.

Again, "too much fertiliser overall" is something that can be tested by amateur growers (as well as in more sophisticated tests); changing nutrient formulations may be beyond the reach of most.

I particularly like small, mounted cloud forest type plants, and would like to grow them well one day, and in the experience of at least one grower of this group, they've noted improvements in their plants under this low-K regime.

Of course, it's entirely possible that people observing success with low K had been using fertilisers meant for "well water" with effectively "pure water" and starving their plants of micronutrients, likely Ca and Mg, which the K-Lite and similar formulations would have corrected irrespective of the K. And I guess that's always the type of question you need to ask - what fertiliser with what water? How much exactly? How frequently? (How much is "a pinch", it's not a recognised unit, and probably varies quite considerably between people; "about once a month" is also vague).

I guess what perhaps you guys are asking for, is that we all need to be a little more "scientific" in the way we report our "treatments" and "observations"; but of course not everyone has a background in science, and even then, not necessarily in the design of biological experiments (living things are very uncooperative in uniformly responding to things, unlike atoms and molecules, which although sometimes very strange in their behaviour generally have predictability in their favour. Living things tend to be more cuddly though). Humans are very good at finding patterns (often spurious ones), love a good story, and are very bad at statistics. As someone who occasionally thinks about how one might relay fairly complex scientific topics to people who have no scientific background (and many who are functionally illiterate), I would suggest those of us who might be comfortable with "doing science" need to cut those who might not be a little slack, and perhaps guide them along to thinking in a more "scientific" way, rather than suggesting that they should get out of the grownup's pool and go play back in the paddling pool where they belong. (I jest, but I do mean the part about being more understanding when people don't necessarily grasp all the finer details).
The simple case that the vast majority of people in e.g. America don't grasp that "Theory" in science is effectively the same as they'd understand as ("common tongue") "fact" is just one indicator of how far the people who understand science have to go in engaging with "unscientific" audiences.

In a past life, before people decided I was more useful playing with computers (and before another taxonomist had viciously stabbed me in the back killing my MSc dead), I was a taxonomist/systematist in-training in fish, which have a rather long evolutionary history compared to e.g. orchids (in the range of an order of magnitude longer), so I stand by 80 million years being "young"; that said, they probably beat our primate line by about 20my. I also spent a spell playing around with coelacanths, which are, again, very old as a group, even though I'm starting to resist the idea of calling them a "living fossil" - something that has great story-telling power (what Pratchett et al call "Narrativium" in one or more of their books), but is not very useful from a science point of view.

In summary, yes, it's kind of unusual that some people have noticed that flying in the face of conventional wisdom seems to work out quite well with regard to a low K "diet" - similarly to how many people notice that adding Ca/Mg to plants that naturally don't have much of either lying about the place seems to benefit them.

I think it's interesting as an observation (in the same class perhaps as Fleming's fabled dirty petri dishes), and interesting to follow their stories, possibly with an outcome of better growing for us all, or at least for some groups of plants.

It is of course worth telling people (particularly neophytes) that they are flying in the face of conventional wisdom and may cause their plants damage by doing so; these are if anything "early stage clinical trials" (poorly controlled ones for the most part), so YMMV.

It's also perhaps worth figuring out in various cases if there are logical errors in their causal assumptions of the "Post hoc ergo propter hoc" sort.

Trials are the only definitive answer (with the caveat that we should really only interpret that as being relevant to the population tested, although we *may* be able to infer/extrapolate from that information on a broader basis). We can certainly say, after looking at what they were doing things along the lines of "look, you were using a well water formulation with rain/distilled/RO" and suggest that perhaps the problem wasn't too much of this, but rather too little of that. That said, enough good amateur evidence may be enough for at least some people to see a benefit for their plants that is "worth trying".

re: the Vanda and Vanilla examples, IIRC Vandas are heavy feeders, and many vanillas are semi-terrestrial. I am wary of course of "special pleading" but phalaenopsis, vandas and vanilla are all (as far as I understand it) relatively "heavy" feeders. If you apply high fertiliser concentrations to a Disa, it will likely die. Ditto with things like Masdevallia, yet some orchids will thrive. Again, an interesting question is whether the problem is one of relative ratios or concentration (or some other factor we're inadvertently conflating with one or other of these things).

In the case of Ray's low-K (presumably vs MSU) trials, I doubt that was the case (micronutrient deficiency) - I also don't know if they're A/B trials of if they're "hmm, this seems good, let's switch everything over to it" trials; in the case of other people, I have no idea as I don't know what they were using before. He has also greatly lowered the concentration of e.g. MSU he recommends in e.g. S/H from earlier recommendations.

As an almost completely useless and entirely irrelevant fact, injecting excess potassium into vertebrates is a very effective way of killing them - it's usually done into the heart, or at least IV, and is reasonably common form of euthanasia (KCl). This is never done in non-anaesthatised subjects if cruelty is to be avoided - this treatment works by doing very bad things to nerves (and cells in general), so is excruciatingly painful. I don't say this has anything to do with plants, or fertiliser, but excesses of potassium do bad things in more than just freshwater mussels.

---------- Post added at 01:27 PM ---------- Previous post was at 01:09 PM ----------

It should probably be noted that I am often quite lazy. I'm quite happy to have a single fertiliser that is "good enough" for most; I am interested in it being the one generally considered to be "the best". In my collection, that means I cater to the more sensitive ones and assume that the hungrier ones will just be a little more sulky/less floriferous. If I'm feeling particularly magnanimous one day I may occasionally "boost" those plants that are known to be hungry, but on the whole, they're on what I guess some might consider a starvation diet (approximately 1/8th of a teaspoon of RO MSU in 5l of commercially ozonated RO water). They seem to grow well enough for me, and I don't claim to be the world's most successful grower - and my experience with growing them is quite short term too.

That said, I put a lot more effort into these plants that the average home grower might, so I guess we need to consider our "advice"/"wisdom" on a number of levels - perhaps "pro"/"enthusiast"/"amateur". Many people don't care what the plant is called, they just want simple instructions so it won't die and will thrive well enough (wtf is a CCM? might say the average owner of a store bought phalaenopsis...). That said, on this forum for the most part we've probably got people that have moved slightly beyond that level (the fact that they don't dump it in the rubbish/trash and buy a new one perhaps tells us that).

[goodgollymissmolly]

wow!! This whole thing exceeds any misunderstanding I've ever seen. Apparently something in the evolution of the human brain makes us susceptible to believing in snake oil commercials.

I do not care what anyone wants to believe. It's entirely your business, but when AOS published the article on Klite that contained a lot of unproven scientific sounding speculation without any kind of disclaimer it made me mad because it appeared to an endorsement of a completely speculative concept. All they had to do was to say, "this is one person's theory for which we have no valid proof but it is presented for your information and consideration".

There was no objective statistically valid experimentation to support these claims. There is considerable literature showing the damaging results of K deficit in plants. A claim as unexpected as this should have been accompanied with validation. Anecdotal observations by untrained observers preconditioned to an outcome is not validation.

I made my thoughts known to AOS, but that is not important. What is important is that an ad is running in Orchids that says, "A formula based on science not marketing hype...Tested and proven by orchid growers around the globe".

Ads are ads. They naturally promote the product, however there is something called truth in advertising and this exceeds the bounds of that. There is no scientifically generated, statistically tested experimentation to support these very dubious claims. This is snake oil advertising and nothing more. Anyone who would run this ad is not on your side.

If this KLite is so good why not get an industry or university source to test it and present objective data? This is not argumentative. It either is good or not. Get some proof. It's only snake oil at the present

[Ray]

Sorry - didn't see this earlier.

Originally Posted by Fabian24

Ray,

You say that you didn’t observe any symptoms of K deficiency, despite using less than half the concentration at which K deficiency symptoms are observed in many orchid genera.
I believe you.
But unless you do a controlled trial, you can’t infer that this is the correct K dosing for fertilizing every orchid.
Do you use inert media, so that you can be sure the medium is not providing extra K?
Do you always water with RO, so that you can be sure there is not an extra supply of K in the water?
Even if you are sure that neither your medium nor your water can provide extra K,
what about sodium, so common in water and media?
It is a known fact that sodium can be temporarily used as a susbtitute of K, in case of need.

I will not claim at all that this is a controlled experiment, but yes, I use an inert medium for many of my plants, and yes, I use RO water exclusively.

I am aware that during the production of the medium, binders and processing aids are used that do contain traces of sodium, but it will be present in only very low levels in the final product, and is easily leached during the preparation and during regular watering early in its use.

I once filled a polypropylene container with the prepped LECA, filled the container with distilled water, sealed it and left it for a year. The analysis of that water showed about 15 ppm dissolved solids, so I am reasonably coinfident that it's not contributing materially to the plants' nutrition.

---------- Post added at 01:33 PM ---------- Previous post was at 12:05 PM ----------

Goodgolly,

1) The K-Lite formula is based upon science. Not Rick's suppositions based upon mollusks, but upon published environmental analyses related to epiphytes and articles about plant nutrition in college textbooks. Nowhere has a claim been made that it is the ideal fertilizer, or that the formula is perfect.

2) The K-Lite formula has been tested and has received positive feedback from hundreds of orchid growers, on every continent except Antarctica, and the total number of testers is expanded-, and length of time of testing actually is much longer-term, as many growers were concocting their own versions well before the discussion went public and the "factory-made" material was available.

Some of the larger purchasers of the stuff are university professors. At least one stated that he was happy to be able to find it commercially, as he had long believed that the potassium in fertilizers was too high. If they want to publish, they will. I am certainly not in a financial position to sponsor a study.

I actually think that all of this skepticism is healthy. I harbor some of it myself.

It's the venomous attitudes and diatribes that are not.

[Leafmite]

I really think that the answer is simple: whatever works is right!
I have been growing plants since I was a small child...I learned from my grandmother who was really amazing with plants. Some of the things she did probably would make all of you scoff but they worked for her and they work for me.
I do love science very much but, in the end, what is most important is what works.
Plants are affected by pH, temperatures, light, humidity, plant medium, frequency of watering, water quality, other plants, day-length, night-day temperature differences and many other factors. As said, too, plants can have very different nutrient requirements. The amount of iron my cinnamon tree demands would likely kill my tea plant. I would never keep potatos or grapes submerged in water but the lotus loves and needs this environment. Cattleya dowiana does not have the same requirements as my aerides.
The environment has a great effect on plants and that, too, must be taken into consideration. Even the air (think dust, smog, humidity, ash, etc) can bring things to a plant. While I have enjoyed reading all the science, I do know that the results yielded in a lab under controlled conditions often fail when applied outside of a lab, frustrating engineers, doctors, and many more. The real world is very different from a lab. The lab and research are the first step, an important step, but still only the first step.

---------- Post added at 01:46 PM ---------- Previous post was at 01:38 PM ----------

Discus, very nice post. Loved it!
Thanks everyone else. Lots of great information. Most of the money for plants goes to agriculture and there is plenty of money spent there. Orchids...not so much. Again, great info from everyone. One just has to look at the different locations to understand why we find different needs in our plants.

[DavidCampen]

Originally Posted by Ray

Goodgolly,

1) The K-Lite formula is based upon science. Not Rick's suppositions based upon mollusks, but upon published environmental analyses related to epiphytes and articles about plant nutrition in college textbooks. Nowhere has a claim been made that it is the ideal fertilizer, or that the formula is perfect.

I have not seen any science. The references in the Lockwood article were either not applicable or misinterpreted.

Is the claim that potassium binds more strongly to potting media than calcium supposed to support this potassium toxicity thesis? If so, where is the evidence or even reason to believe that potassium binds more strongly to potting media than calcium? What is the supposed mechanism by which this causes potassium toxicity?

Where is the evidence that orchids live in a potassium deficient environment ?

Are there any other reasons to believe in the validity of this potassium toxicity thesis that are supported with more than pure speculation?

[Ray]

David, the formula was devised with the help of a professional plant nutritionist who had never read Rick's article or knew one was in the works.

It was based upon scientific articles and textbooks I have referenced in the past.

I cannot speak for anyone else, but the long-term negative impact of excessive potassium exposure to orchids is nothing more than speculation in my mind. However, as I have stated more than once, other - unrelated - scenarios involving the interference of potassium in natural and chemical systems do lend a modicum of potential credibility to the theory, which is why I'm willing to experiment.

You are certainly free to have your own opinion on the matter, but I fail to see why you think I don't, and choose to fight it so vehemently.

[goodgollymissmolly]

"It's the venomous attitudes and diatribes that are not."

I guess it's a "venomous diatribe" to point out that you make claims not proven in order to market a product that defies conventional wisdom. Thank you for that nonsensical insult

"I am not in a financial position to sponsor a study".

But you are in a financial position to run ads promoting the product you can't afford to test? Thank you for that.

I repeat what I said before. People have grown fabulous orchids for over 200 years using the traditional understanding of fertilization. I guess I have ask how much better could they get? Are there things to be learned? Yes and there always will be, but those those things will not be learned by anecdotal experimentation of doubtful value pushed by false advertising.

Get some data from a controlled experiment run by a trained scientist. Hundreds of orchid growers around the world (an outright exaggeration) are meaningless. I read nonsense by hundreds of orchid growers on forums evey day. Experiments by amateurs are tainted by unknown variables. To suggest that there is a magic potion that nearly overnight miraculously improves your orchids is absolutely ridiculous. It is the wild Wild West snake oil salesman on the Internet.