Paph. delenatii leaves dying
 

So, I've ordered quite a few paphs over the last year and they're all doing well so far..except for delenatii.

I bough the plant and it had 5 leaves. In some month and a half the bottom two leaves died and the third one is in process right now. They first go somewhat limp (not sturdy like other leaves) and soft. They start yellowing...then they turn brown, crisp and dry.

The plant is not in a transparent pot, so I can't see the roots without unpotting.

The plant is on a northern windowsill, right next to a brachy hybrid, Paph. Magic Lantern and Paph. Envy Green, all of who are growing very well and not showing any issues. I water the plant every 4-5th day, it's planted in bark. The room temperature is cca 20-24*C, humidity is not very high, 40% perhaps. I sometimes open the window for 15mins to cool down the room, but not too often, maybe twice a day during daytime.

What could be happening with the plant? Should I repot it? (I can attach photos when I'm back home and update the thread)

I think your instinct to unpot and check the roots is a good one, so start there.

I have unpotted it and literally all roots were soft and I was able to peel them off with very little effort. I was left with a rootless plant in the end, the photos of the plant and dead roots are attached. Is there any hope for it (I see that little growth at the base)?

I have taken it like that and potted in dried sphagnum moss (3rd photo), should I move under LED lights or cover it with a glass bowl to increase humidity?

As long as it's not getting any direct light that would cook it, the glass bowl sounds like a good idea to me.

It's too bad about the roots. Are your other Paphs potted the same way? My P. delenatii is just seedling size, but it's been really tolerant of cool temperatures so far and I've seen temperatures between 26 and 13 degrees C listed as normal so I would't think that's an issue?

I have purchased this plant from an online seller from whom I've purchased a few other plants. I have not unpotted any of them (except for this delenatii) because I plan to repot them in spring. They do seem to grow very well, so I believe their root systems are healthy. On the other hand, this delenatii hasn't moved one millimeter since I got it two months ago. I suspect the roots were already starting to die back then or were already dead and it just took it this time to slowly drop each leaf...wish I had unpotted it sooner! The seller, to their own admission, is just a "reseller", they don't grow the plants themselves like a nursery...I previously received one plant with a few mealybugs on it and the seller apologized and immediately offered to refund, so I don't hold a grudge against them, lol