Pale yellowish leaves - why????

[swamprad]

I’ve been growing paths for more than a decade and have over a hundred of them. I have always had a problem with leaves turning yellow. Losing the healthy green color. I buy a beautiful green paph and a year later it is pale and yellowish. I'm not talking about normal senescence of old leaves. I suppose the plant is stressed in some way. Why, oh why does this happen?



I don’t think it’s fertilizer, I regularly use MSU fertilizer, as well as monthly Kelp supplement.



I don’t think it’s light, I grow under LED lights.



I repot annually in orchiata/sponge rock mix.



I water when they approach dryness, 2 - 3 times a week, and most plants have great roots when I repot them.



Could it be my water? We have some of the purest water in the country, very low TDS, but I’ve recently installed an RO system to see is that makes a difference.



Please, any suggestions? I've got to figure out what to do differently. This is driving me crazy!



Photos are two seedlings of Ho Chi Minh, all pale and bleached out, next to a smaller green micranthum for comparison. The other photo is of a multifloral with great roots and growth, just yellow and pale, next to a greener bulldog for comparison.

 

[big923cattleya]

I am sorry but I disagree with your assessment. They do NOT look yellow at all. Across the board I don’t see a real issue.

I am not a big believer in fertilizer as it can be easy for some one to over fertilize things. I feed generally twice a month at half strength. The fact that you mention good root development is a huge plus.
I do not think the 2 Ho Chi Minh’s looked washed out. It could be a little too much light.
Type of tubes
Distance above plant leaves
How many hours are the lights on
These are just a few of the parameters of slippers under lights.
I use ten hour days in the winter and twelve hour days in the summer. Leaves are 8-10” below the tubes. I use a finer mix then you do. 50% seedling bark. 25% perlite and 25% seedling grade charcoal. I water every 3-4 days. Humidity runs 45-60% in the winter and 55-80% summer.
It could be a nutritional problem but it does not sound like it to me.

 

[spujr]

Do you use the MSU formula specifically for RO? What is your feeding strength when you water?

What are your light levels? Can you measure the PPFD/PAR?

Without knowing these I can only make general suggestions. Try switching to a different fertilizer. I've been using Green Jungle and have been happy with it so far. Others have good results with K-Lite from First Ray's.

 

[spujr]

I also agree with BigCat, those photos look like reasonably healthy plants.

 

[Ray]

Describe your feeding regimen in detail.

 

[Ozpaph]

too much light (the new leaves are fine)

 

[hope]

It's possible the light is a touch too strong. Try raising the lights a little higher or reducing the amount of time they are on by an hour or so and see if that helps.

 

[swamprad]

Thank you all for your above comments. I use K-Lite from First Ray's, 150 ppm weekly. In the winter, I reduce the ppm to 75. I add the First Ray's kelp 1 tbsp/gallon monthly. I grow on 2x4 ft shelves, under two 2-bulb LED shop lights (so 4 bulbs per shelf) and the plants are about 8" from the light. 12 hours a day in summer, 10 hours a day in winter.

Maybe my lights are too close to the plants.

I occasionally give Epsom salts, 1 tsp gallon. Does that really work to green-up foliage? It's never seemed to make any difference that I could tell.

 

[spujr]

From what you described, I would suspect you are providing too much light. 4 bulbs seem a lot. That said, bulb size won't determine light strength and if the leds are low then 4 might be ok. You can get a smartphone app that can measure your lumens, which could provide an indicator of your light levels (PAR or PPFD measurements are better but not sure if a smartphone can measure this).

 

[Theodoreorchidking]

I have a plant like this and it seems to be ok. It could be a lack of calcium: not exactly sure what this looks like but put some oister shells on top. Also it could be realy strong light use an app on your phone to see the leval. Good luck

 

[big923cattleya]

I just have one question and maybe it can be cleared up easily.
If you have some of the best water in the country, why go to an RO system? Doesn’t that remove every thing from the water? During the 9 years I spent in south Florida, the water was so bad that RO systems were very popular. All of my orchid friends had to add nutrients back into their water.
I myself never used RO water. I had a well, my orchids looked good and I really didn’t think about nutrients much.
I was a big fan of 20-20-20 Jacks at half strength. I like Dynamite 18-18-18 too.

I have one other observation to report about. I am a meticulous record keeper. Over my orchid career, I noticed after using a fertilizer for 5 or 6 years, flower counts dropped rapidly. When I switched from DynaGro to Champion, flower counts went up immediately. When those rates fell again I went to Jack’s. Numbers went up again. I still switch brands every 5 years or so. My flower counts are consistently good.

 

[terryros]

You need to be able to measure the actual light intensity at the leaf level. You should do this measuring peak photon flux density in micromole/meter squared/second. This would be fairly accurately done at moderate cost with an Apogee full spectrum quantum flux meter. For Paphs you would want to be in the range of 50-100. The meter costs several hundred dollars but it is worth avoiding poor growth, poor blooming, or going crazy worrying. Both deficient and excessive light intensity for will work against optimal growth and flowering.

 

[Theodoreorchidking]

No don't spent hundreds of dollars. Download an app on your phone first. Then turn the light down/ put it farther away and see what happens. If they turn a better color them great. If it does not then I would try calcium and or just use tap water for one of your plants.

 

[Happypaphy7]

Those two HCM are definitely bleached.
Too much light for sure.
Either move them to natural light or reduce the number of light bulbs/tubes, or increase the distance between the light and the plant.

 

[Theodoreorchidking]

Also do you get good blooms/ flowers and does the plant keep growing? If so I would just the light down a tad and keep sailing forward

 

[PeteM]

In my experience orchid leaves will turn yellow:

1) watering with pure RO water. You should always cut RO water with something, never water by itself. Unless you are flushing the plant, even then do this rarely.

2) too much light and heat.

If the RO system is new to your culture, I suspect this could be the issue.

 

[Roth]

They are definitely bleached and extremely deficient, that's for sure.

The leaves should be much darker, and it is not light related, otherwise the symptoms appear very quickly.

As well the newer leaves are smaller and smaller on the multifloral, which is not normal at all, the same for the 2 HCM, the new leaves are about 30% smaller than the older ones...

You must use a fertilizer that contains urea and/or ammonium, a simple urea-based 20-20-20 will improve the things greatly, especially if you have a lot of light. Check your drain water pH as well, and keep it below 6.2 max, over 5.2 min, roughly...

MSU or nitrate based fertilizers are definitely not giving good results for paphs, except in a few very specific odd circumstances.

 

[big923cattleya]

I just checked the AOS website just to make sure that the World was still spinning on its axis! It is. They distinctly recommend a fertilizer without urea for all orchids. The only exception is terrestrial orchids because organisms in the oil help the orchids to break down the nitrogen based urea so that the orchid can utilize it.
They suggest an even strength fertilizer like 20-20-20 with trace or micro nutrients. Orchids grown in bark mixes for example can not handle urea based nitrogen.

 

[Roth]

I just checked the AOS website just to make sure that the World was still spinning on its axis! It is. They distinctly recommend a fertilizer without urea for all orchids. The only exception is terrestrial orchids because organisms in the oil help the orchids to break down the nitrogen based urea so that the orchid can utilize it.
They suggest an even strength fertilizer like 20-20-20 with trace or micro nutrients. Orchids grown in bark mixes for example can not handle urea based nitrogen.

Well, without urea and ammonium, many plants will struggle, there is no question possible about that...

They repeat like a parrot what others repeated, but there is no background or scientific research at all regarding this kind of statements.

Orchids grown in bark mix can handle urea based nitrogen, in fact 100% of all the Paphiopedilum and Phalaenopsis grown in Taiwan are grown using urea, and 100% of the 196 millions Phalaenopsis grown for pot plant on the European market. So urea might well work after all... My entire collection depends on it too...

 

[big923cattleya]

There is evidence that seems to contradict what you are saying. That is all that I am pointing out.