Yellowing Paph and Phrag Leaves

[melisa]

All of my paphs and phrags have great roots and new growths, but the very bottom leaf turns yellow and dies. It happens to all of them except for my brachys. I tried changing fertilizers, from a balanced one to K-Lite, with no success. I have also tried epsom salt to see if that helped. Does anyone have any ideas on what is causing this? They seem so happy otherwise. It's driving me crazy trying to figure it out!

 

[NYEric]

Could be normal leaf die-back.

 

[SlipperFan]

Some photos would help.

 

[abax]

All orchids that I have grown over the years shed old
bottom leaves. I just whack them off. It's normal.

 

[melisa]

Here are a couple of phrags that are yellowing. The first one is starting to yellow on the upper leaves as well.

 

[Stone]

We typically see this when a new growth is getting under way. I believe it is drawing nutrients from it's mother plant - the older growth.
We need to know more exactly how and what you are feeding, the temperature and light etc. The p/mix looks quite bony so you may have to feed lightly but continuously every time you water. Nitrogen is always the first to consider with old leaves yellowing. followed by P,K,S, Mg, Mo.
trouble is, that when the old leaves yellow they never return to green in my experience so you will need to observe for a full year to see if you have rectified the problem - and there is a problem - especially with the first plant.
I have found a slow release form of organic fertilizer (solid) almost always helps to avoid this. (as long as there are active roots) Some blood meal would be a good start. As much as would cover a dime once per month is enough. Something which holds cations incorporated into the mix will also help. Coco chips or a tiny bit of peat, something like that.

 

[NYEric]

How much light...???

 

[melisa]

I was using Dyna Grow at 1/4 tsp per gallon every time I watered, which is usually every three days, and have most of my phrags sitting in about a half inch of fresh water. Now I am using K-Lite at 1/2 tsp per gallon once a week. I change the water underneath them every three days and run enough water through the pot to fill up the pan. They never sit in fertilizer though.
I always use spring water for my phrags and tap water for my paphs, so it's not the water causing it.
The temperature is around 75 during the day and 63 at night. The humidity stays around 75% where they are. It never drops below 50%.
Both of those phrags are under lights at about 1000 footcandles for 12 hours a day. Others are on a northeast facing windowsill. They yellow just the same, along with the paphs.
The one in the first photo is the only one where the whole plant is suffering. A few months after I got it five new growths started. Could that possible be too draining on the plant?

 

[Stone]

I A few months after I got it five new growths started. Could that possible be too draining on the plant?

Well you have to remember that the new growths don't have roots so they have to get nutrients from somewhere. 5 new growths is a lot for one plant to sustain without losing condition.
Your temps are a bit on the cool side but not too bad I guess. The dyna grow ''grow'' is 7-9-5. That seems too low in Nitrogen to me. (I don't know what you are using) It's also low in K. K-lite, well what can I say. I would find a better fert, higher in N and K to start with.

 

[melisa]

Thank you for the advice! I'll start by trying a new fertilizer. Is there one in particular that you would recommend that I try to help rectify the problem? There are so many different choices, and it is hard to decide on one. I know that I'll have to find one that works best for my growing conditions, but I am up for recommendations!

 

[Stone]

I don't know what is available there but something like 30 5 20 would be better I think. But as I said it will take some time to notice a difference.