Nutrient deficiency?

[Cochlopetalum]

Your plants had nice leaf color this winter. The only thing that changed is the time of year. I turn off my lamps in the spring and hang sheer curtains for the summer. Otherwise I also have bleached and burned plants in my east window. You just need to turn off lamps and hang mosquito netting or similar and they will soon be normal.

 

[Garr]

Urea

I'm afraid that I'm somewhat late to the game here. You were counselled, among many other suggestions, to try using urea. Prior to changing light intensity, day-length, substrate composition, fertilizer regime or anything else, I think that a somewhat more conclusive diagnosis would make sense. Without changing other factors, a foliar spray would, without any other variables in place point out a potential N deficiency...or not. A word of caution. Urea CO(NH2)2 or 46-0-0 is a very powerful N source. It takes only about 0.21 grams/liter to achieve a concentration of 100 ppm. Confusing the issue is that you can't double check your concentration after the fact with an EC meter as the solution is not conductive and will register 0.0 µS. Care needs to be exercised as a typical 1/2 tsp/gallon solution would yield a whopping 300 ppm solution.

A light foliar spray at 100 ppm of urea repeated a couple of times a week will in fairly short order confirm if there is in fact a N deficiency as there will be little to no interaction with substrate chemistry to confuse the issue. Once this is established, you can then examine substrate pH, N ratios, micro nutrient deficiencies, light levels and other cultural factors which may be contributing to the yellowing.

I hope that this helps and would be very curious to know what has transpired since the last posts.

 

[The Mutant]

A small update:

So, what have happened after my first post was made? Well, except me getting depressed and feeling like the worlds worst Paph owner, I tried to change everything.

* I raised the T5 (it's currently 18" above the Paphs, and I'm thinking about raising it some more).
* I reduced the hours it was on (as it wasn't necessary when the morning sun was shining through the windows).
* I shaded my orchids from the sun (which I always do, but better to be clear about it).
* I changed fertilizer.

The result is that the roth that had turned almost yellow, Starship x self, is now almost back to the same green it had when I got it. Overall, they've all greened up and shown signs of better growth.

Since I changed so many things, it's hard to say if it was only a light issue, or if it was something more. I'll start using k-lite again and see what happens. Hopefully it was only a light issue and nothing else.

Anyway, thank you all for all of your many, MANY suggestions and tips. I thinks it's thanks to you that the victims seems to be restricted, so far, to only two Paphs; my smallest roth Kim Crull x Canadian Club, and my biggest philippinense var roebelenii.

 

[Garr]

What fertilizer did you change to?

 

[Ray]

About 8 weeks ago, I acquired about a dozen tigrinum primary hybrids (all the same cross, but I cannot recall it at the moment). They were given to me because they were very yellow and "not up-to-par" for the commercial grower. They were green and deep yellow, not "bleached out".

They are outdoors, receiving only indirect light as it passes through the greenhouse roof and front wall - plus back-scatter from the sky - and received one watering with K-Lite at 35 ppm N when I first got them. Since then, Mother Nature has handled all feeding and watering - i.e., lots of flushing with pretty pure water.

The plants are greening up quite well.

 

[The Mutant]

What fertilizer did you change to?

I've mostly used Blomstra for orchids and for regular indoor plants. Since I can't get my hand on ammonia/urea without some serious paperwork etc. (which I haven't had the energy to do, seeing as I've managed to bring myself to the brink of a burn out again), I figured this would have to suffice.

About 8 weeks ago, I acquired about a dozen tigrinum primary hybrids (all the same cross, but I cannot recall it at the moment). They were given to me because they were very yellow and "not up-to-par" for the commercial grower. They were green and deep yellow, not "bleached out".

They are outdoors, receiving only indirect light as it passes through the greenhouse roof and front wall - plus back-scatter from the sky - and received one watering with K-Lite at 35 ppm N when I first got them. Since then, Mother Nature has handled all feeding and watering - i.e., lots of flushing with pretty pure water.

The plants are greening up quite well.

If I could have done that, it would have been a good choice. Now I'll go full RO and K-lite and see how they respond. I'll update this thread again when/if I see any results (good or bad).


Again, thank you guys.