Light looks good, and humidity is rarely if ever an issue. I have never ever heard of a phal dying from low humidity before. I suspect the problem is the moss-bark mix.

Personally, I don't believe in this idea of top-dressing with sphag, mainly because I've found that when allowed to dry, sphagnum moss turns into an impermeable moisture shield. I'm sure you too have seen this happen - the water just runs off the moss unless you give it a good soak.

Subsequently, you have a crusty layer of dried sphag, and a sopping mess of bark underneath that can NEVER dry out properly. Try it - layer some sphag over some bark in a pot (I'm assuming you are using plastic?), water it as would your orchids. As the moss looses fluff and compacts, it will turn into a dry disk, while the bark underneath will remain wet and soggy. With uniform moss, at least the entire moss wicks moisture from itself so you get more uniform drying. This is what works the best for me. Bark, I can never use in my environment, so I won't bother giving you advice with that.

I have experimented with a mixed sphag-chunk, bark, and charcoal mix with decent success. I believe the mix of mediums with different water retention properties (charcoal - none, bark-moderate, moss-maximum) and different sizes helps in some mysterious way. This is, however, completely different from a layer of sphag over a layer of bark.

I'd say chuck the two layered potting method

Can you post a picture of your light setup, por favor? Thats one thing that strikes me. How many lights do you have, and on how many plants? How far are they away from the plants?

How are the temperatures?

I'm completely with Calvin on the other points. Humidity really isn't an issue for potted Phals (I'll reserve that statement for non-desert areas. no clue how well phals hold up in deserts).

The topdressing with the moss is kinda pointless since the moss will dry out so quickly (I've done this a few times in the past). Just mix it in with the bark when you go to repot the plants instead of top dressing. I'm incline to agree that this seems more of a potting mix-and-watering issue than anything else.

In the cold north with desert humidity, I top dress without problems. But I don't grow Phals in straight bark. I have sphag or perlite mixed in the bark. I throw some CHC in also (not alot).

The problem I run into during winter is the cool temps. Some phals can take cool temps for long periods, others start to show stress. I've had crown rot during winter which I believe is more stress related then getting water in the crown. During summer, I've never had crown rot.

Light is the most important element. Forget humidity, not important, get your light and watering worked out. I keep the few Phals I have quite dry over winter. Remember, wet and cold will lead to root-rot. Better to increase light and water when you are sure the media is almost dry.

Jane

I have considered all of your comments above and agree that the only change which could have caused the deterioration was my change in potting to bark on the bottom and moss on top. Today, I repotted all of them into uniform bark/perlite mix. So, there is no longer a separation of materials from the bottom of the pot to the top. I thought I was doing something right but clearly the orchids did not like them as they have suffered root rot and loss.

My Phal Brother Sara Gold is in the worst shape with every few roots. But it is growing a spike. I assume I should bite the bullet and chop off the spike prematurely so it can devote its strength and resources to growing roots and not growing flowers? Am I right that as much as this pains me, it will be better for the plant? TIA!

Yep, give up the spike :( Hoping for you its not a death spike, given your description of your other phals.

Have you tried S/H at all?

Hello everyone! I am also new here and love phals. They are so easy for me to grow and bloom but I have a diffrent problem. One of my phals is quite old and has many leaves. The problem is it has grown quite lanky. I have read that you should cut the top off in a way to retain as many roots as possible. It does have a very large amount of air roots. Is it easy to cut this orchid and repot? Will I have to worry about the cut portion rotting? How should I water without risking the cut crown rotting? Thanks for any help!!
Andrew