# yellow leaves on paph. gigantifolium



## musa (Dec 14, 2020)

Hello,
my gigantifolium is getting yellow leaves what makes me realy nervous.
On the first two fotos taken under grow lights it is obvious. For comparison it stands between kolopakingii (left) and platiphyllum (right). The last two fotos are done under normal light withour flash.
I already repotted it, it's in orchiata with a bit of marble gravel. Rootsystem is not perfect but there are four growing root tips. For some weeks it gets an extradose of epsom salt. How should I go on?
I really appreciate your help!


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## GuRu (Dec 14, 2020)

Michael, I think you potted the plant a bit too dep in the potting medium. Therefor the very low leaves are rotting at their base.


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## Ozpaph (Dec 16, 2020)

probably no roots


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## musa (Dec 16, 2020)

Thank you both.
I'll take away some potting media to give room to the lower leaves.
With four growing root tips roots are not too good but I didn't imagine it would have such an effect. I already repotted it, what else could I do to induce root growth?
Thanks


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## Martin (Dec 16, 2020)

I heard that a fertilizer with high K Help root growing. There is one called Plantstarter, which has about 40 K


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## masaccio (Dec 17, 2020)

Is there a chance that you are over-lighting? The plant on the other side of the kolopakingii also looks a little yellowed.


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## musa (Dec 18, 2020)

Thank you both!
They are under two tubes 36W growlight of OSRAM. I non't think that is excessive, but I cut the light down 1,5 hours per day. 
What you can see on the far left is intaniae. You are right, massaccio, that it is a little light, too. However the gigantifolium is worse and I'm most worried about.
Martin I'll keep the K in mind and will see to to find some extra.

What I'm worried about as I can't explain it are the little dark green dots on the leaf in the second foto (post1). Might there be some kind of infection?


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## masaccio (Dec 18, 2020)

These are LED tubes? I don't know about OSRAM. They have a wide array of products so it's difficult to deduce your particular product. The red flag for me was 35 watts of LED light. I use 26 watt LEDs (2600 lumens) Sylvania spots for growing Cattleyas and those are roughly 20" away from leaf TIPS. For paphs, its 19 watt CREE spots (1500 lumens), which are almost three feet away from horizontal leaves on roth crosses. But my PPFD ratings are quite satisfactory. I run them 12 hours a day. I don't mean to be bulldoggish about this, not knowing anything about how long you've been growing, your rate of success, how long you've had the plant in question, etc. I just wanted to suggest that the plant, if generally stressed by excess light (which is a common error for for LED growers - including myself), it could be suffering from more than one sort of malady but from a common cause. Good that there are living root tips. Best.


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## terryros (Dec 18, 2020)

I agree that knowing the light intensity (the peak photon flux density) helped me a lot. I don’t buy cheap plants and found that the cost of the Apogee full spectrum meter that measures the PPFD in the PAR range is about the cost of 1-3 plants I might by. I don’t have 30 years of growing left to just use trial and error to find out about the right light levels. You can’t tell with your eyes. I haven’t wanted to just raise or lower lights and wait months to see if there is a change In the right direction. I know my approach would be different if I were young and on a tight budget.


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## masaccio (Dec 18, 2020)

terryros said:


> I agree that knowing the light intensity (the peak photon flux density) helped me a lot. I don’t buy cheap plants and found that the cost of the Apogee full spectrum meter that measures the PPFD in the PAR range is about the cost of 1-3 plants I might by. I don’t have 30 years of growing left to just use trial and error to find out about the right light levels. You can’t tell with your eyes. I haven’t wanted to just raise or lower lights and wait months to see if there is a change In the right direction. I know my approach would be different if I were young and on a tight budget.


I found your recent posts (and several earlier ones) brilliant and so helpful to my struggle. Bookmarked forever. I"m ordering the Apogee myself in 4 days, and counting. Thanks so much.


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## GuRu (Dec 19, 2020)

masaccio said:


> Is there a chance that you are over-lighting? The plant on the other side of the kolopakingii also looks a little yellowed.



Of cause, overlightning can be one of the reasons of yellow leaves......but in this case I would say by my experience.....it isn't. Overlightning would have affect to almost all leaves and the upper leaves, which are the closest to the light source, would be affectect more than the lower ones. But here the upper leaves seem to be healthy and only the lower leaves are turning to yellowish.


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## musa (Dec 19, 2020)

Thanks a lot for your help, I hope the following is kind of useful.

Just by my feeling I'd say light isn't the problem as I brought many paphs, mainly coryopedilum, from seedlingsize to bloom. Some issue I had with gigantifolium, and anitum. I grow under the same light conditions from the beginning in 2012.
But of course might light be the trigger to the problem of my gigantifolium.

Nevertheless I tried to find some more information on my lights:
Osram fluora 77, flourescent tube, 36 watt, length 120 cm, 1400lm. That is official.
In an other forum I found the following:
6,48 PAR Watt, 29,1 µmol/s PAR PFF

Per shelf 25 cm x 40 cm I have 2 flourescent tubes at a distance to the tips of the leaves of about 18 cm. I had them running 14,5 hours a day, now I cut it back to 13 hours.

Unfortunately I do not have a full spectrum meter.


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## GuRu (Dec 19, 2020)

musa said:


> .......Just by my feeling I'd say light isn't the problem.........



Michael, I want to insist to my post #2. You wrote you removed some potting media. Did you look closely to the base of the lower leaves? Was there a zone with a width of aproximately 2-4 mm like a ring with brown decayed tissue?


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## masaccio (Dec 19, 2020)

GuRu said:


> Of cause, overlightning can be one of the reasons of yellow leaves......but in this case I would say by my experience.....it isn't. Overlightning would have affect to almost all leaves and the upper leaves, which are the closest to the light source, would be affectect more than the lower ones. But here the upper leaves seem to be healthy and only the lower leaves are turning to yellowish.


Absolutely. I stand corrected. It appeared to me from the first photo that all the leaves were yellowish. I"ve enclosed a photo here that may illustrate the problem you are describing. I found it on my recently arrived Prince Edward of York.


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## GuRu (Dec 19, 2020)

masaccio said:


> .......I"ve enclosed a photo here that may illustrate the problem you are describing. I found it on my recently arrived Prince Edward of York.



Exactly, that's what I ment.


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## hamiltons (Dec 19, 2020)

Hi Musa
First I would like to say thats its cool that you have got this rare plant, P.gigantifolium, its not so easy to get and its very expensive in this size which is the only size to benefit from, its a very slow growing species, so getting young plants of it will take years and years to bloom...Next I think I will give Guru right, it seems that the plant and maybe other of your fine species are potted too deep so the lower leaves first turns yellow and next rot and fall off, due to the very moist/wet media around the roots, which will also get wet and soggy and eventually rot and in the end the plant will have almost no roots and therefor the plant will be in grave danger of simply slowly dying and its very difficult to get it back...I have myself grown slipper species for more than 25 years, close to 30, and have tried almost all kind of medias to grow in, bark, sphagnum, gravel etc. and is now growing all my orchids (except for thick rooted plants like Catts and Rhyncostylistylis etc) in a special produced rockwool mix for orchids called greenmix, produced here in Denmark, a blend of water resistant and water absorbant rockwool/grodan added with a small bit of lime gravel, considering species etc. and I have been growing in this for more than 25 years now and its the best damn mix I have ever used, is good to use whether you grow in greenhouse or windowsill, the only problem is that it is not good to keep too wet and cold for warm growing types, roots will stay to cold and die if too wet too...So regarding your gigantifolium and other fine paphs, try to repot it and keep it a bit higher in pot, not so roots will be above pot edge, but just so it stays in the pot top line, and if you like the media you have your plants in, of course continue with this, but I would recommend that you try to get a portion of the rockwool "Greenmix" for orchids and experiment with maybe a couple of not so valuable plants and see how it goes, its a media easy to work with, it shall not be pressed hard into the pot but just be put carefully into the pot around roots and softly packed, and thus carefully wtered with clean water and kept fairly moist but not wet...I have all my paphs and other orchids in a small 3 x 3,5 m greenhouse on our balcony, and in winter I use a small electric heater with thermostate to regulate temperatures and in summer whatever temperature the outside weather generates, in hot days I use a fan to ventilate the air, and I shade quite much as the sun gives much light and heat, so temps will get very high sometimes if not shaded and ventilating, Summer temp. app 28 degrees in day and 20 degrees at night, and in winter the temps. should be about 5 degrees lower over all, and in winter it gets quite dark outside, but my paphs still just get what they can from outside, except for a couple of hours in the late afternoon where I turns on a large "plug and grow" tube that is mounted into the middle of the ceiling in greenhouse, this I do from November to february and then natural light again...For watering I use natural rain water and in periods when not raining so much I use cleaned water from a reverse osmosis aggregate, and I use a fourth of the amount recommended fertilizer and fertilize every time I water in summer (may to September) and then set the fertilizer down to only once a month or not when watering...I hope that this is a bit helpful to you and maybe also to others, we all have different growing conditions and methods and should of course stick to that if it works, all this here is just an example of how I do, and with a few tips too...Hope it was helpful and have a continued great day and merry holidays soon  I will try to attach a few photos of my greenhouse/plants


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## musa (Dec 20, 2020)

Thanks a lot, your advice is most appreciated.

I just removed the top layer of the potting media and discovered brown spots (Foto 1 and 2), but then I realized that it was the rest of an old leaf which I could remove (Foto 3 and 4). On the 5th foto you see how the plant is now leveled in the potting mix.
As you can see I keep it a bit on the drier side, the top of the pot dries out before watering while the lower pot is keept moist all the time. On the last foto you can see growcubes which are added in the top layer of the pot. I think theese are what you mentioned, hamiltons. 
I could remove the oldest leaf which has a slight brown hue at the base but I don't think it is a good idea. What is your opinion on spraying a copperbased fungicide?
One other thing is temperature, it is quite high. At the moment I have 28°C, at night it is about 21°C. Might this be a problem?
Humidity is 50%.


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## Ozpaph (Dec 20, 2020)

i would not use a fertilizer with K=40.


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## musa (Dec 21, 2020)

As it it recently repotted and roots are already growing I won't. In fact it'll get low fertilizer for some days, till It has established again.


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## musa (Mar 2, 2021)

As suggested elswhere I covered a leaf partially with paper for over a week, but there war no change in colour where the paper has been. Rules that out too much light, or is stress by overlightening still possible?
The new growing leaf is darker, but still on the light side; I can see still four active root tips like in december and they are growing. That's not overwhelming but at least there is a working root system. 
The base of the plant is now higher in the media and there are no signs of rot.
Thank you very much for your help!


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## Ray (Mar 2, 2021)

I know I'm jumping in late here, but have you considered watering it with an Epsom Salts solution? 1-2 ml/L ought to green it up.


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## musa (Mar 3, 2021)

Hello Ray,
your help is much appreciated! I tried that, as you mentioned it to me on a similar problem. I gave it once a high dose of epsom salt in water (300 µS) and twice a small amount with my regular fertilizer. But on the gigantifolium there was no recognizable effect. I hope the dosage was ok?


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## Lucienne (Mar 3, 2021)

I have the same problem with phillippinense. I heard the opinion that such a condition may indicate a lack of calcium. I added dolomite flour, but I don't see any progress.


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## Ray (Mar 3, 2021)

musa said:


> Hello Ray,
> your help is much appreciated! I tried that, as you mentioned it to me on a similar problem. I gave it once a high dose of epsom salt in water (300 µS) and twice a small amount with my regular fertilizer. But on the gigantifolium there was no recognizable effect. I hope the dosage was ok?


That’s really not a very high dose. My understanding is that Epsom Salts adds about 7µS/cm per ppm Mg, so your 300µS dosing was about 43 ppm Mg, which falls in the range of recommended level for someone feeding 100 ppm N weekly (30-60% of the N).


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## musa (Mar 3, 2021)

Hello Ray,
so I'll give some more. What would you suggest? Above you mentioned 1-2 ml MgSO4 solution per liter. As I have Epsom Salt as powder how much would that be in mg?
As for the calculations I'm completly stuck. 1 ppm of Epsom Salt = 7 µS. Is Epsom Salt so very different from other salts, as I found several tables and calculators which give different figures. e.g. this calculator says 1 ppm = 1,56 µS without explicitly refering to MgSO4. How is that possible?
Sorry for all that confusion, but I'm no chemist at all and I try to get it right. I hope you won't get mad at me...


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## Ray (Mar 3, 2021)

musa said:


> this calculator says 1 ppm = 1,56 µS without explicitly refering to MgSO4. How is that possible?



It's not. There is simply no way it can give a reasonable solute concentration, because different ions have different conductivities for the same ppm concentration and they can change when in combination. 

The best way I know to demonstrate that is by comparing MSU WW, MSU RO, and K-Lite, three fertilizers made up of the very same ingredients, and look at the normalized values (normalized to the MSU WW):


► For a 100 ppm N solution the RO has an EC that is 18% higher than the WW formula, while the K-Lite is only 4% higher.
► The True TDS of the RO formula is 40% greater and K-Lite 45% than that of the WW formula.

The calculator you linked to, when using the EC's provided by the manufacturer (the first row), would give TDS values of 435, 512, and 454 ppm, respectively, so would under-report them by 20%, 31% and 41%.

The number I was given by a professional in plant nutrition was that Epsom Salts (MgSO4-7H2O) provides about 7µS/cm per ppm Mg. I recently read another article that said 7.6, but that's close enough either way.

From a practical perspective, anywhere from 1/8-1/4 tsp/gal weekly, or 1/2-1 tsp/gal monthly is fine.


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## musa (Mar 4, 2021)

Ray, I'm very grateful for this.

I hope I got the calculations right in accordance with my equippement. 
To get 1/2 tsp per gal I put 1/4 tsp (~ 1.2 ml) in 2 l. That is on my scale ~1700 mg Epsom Salt per 2 liters of water. As I understand it that would be 850 ppm.
My EC-meter shows an augmentation of 700 µS.
The values still don't fit, but maybe my scale or EC-meter are out of order.

I'll try that today and report on the effect.


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