Phal has dark red turning black under leaf

[camille1585]

Originally Posted by RosieC

Some orchids have a naturally redder pigment than others (often redder ones also have red/purple flowers).

Also higher light levels can turn leaves red or give them a red tint.

I also read here on OB recently that not enough of a certain cemical could cause a red tint under the leaves, but that the amount needed was so tiny that was not normally a problem (sorry can't remember which cemical it was).

Phosphorus is what you're thinking of. Phosphorous deficiencies are usually not a problem for most plants (except for weed culture) unless you never ever fertilize, or have drastic pH problems that cause element blockages.

I agree that it sounds like the plant just got too much ligt, but what sounds strange is the speed at which it appeared. Last summer I misjudged the movements of the sun at my south window, and I left the phals there, and they turned competely red/purple, but it appeared over the course of a week, at least. And the purple was on the top surface of the leaf, there was nothing underneath. If it was sun that caused that on yours, moving it to a shaded spot will make the color fade away almost completely within 10 days. If the color stays as intense, it wasn't sun.

[RosieC]

Phosphorus, that was the one, I had a feeling it began with P.

I agree, the speed of change is strange and it should start to fade once it is moved away, if it is related to light.

I've noticed red on the underside of the leaves on some of mine BUT the leaves in question stand rather upright and so it is the underside which has been towards the sun.