Dick Wells at Hilltop Orchids in IN grows everything in mud masterfully. We can't. It can be done, but there's some "secret".
-Ernie
Boscha Popow and me were the only 2 successful in Europe to grow all orchids, including all the paph species in mud mix. A few others I "teached" could do it, but if you do not know the "secret", that's a real failure.
The source of the mix was Bas van Buuren, and the peat had a lot of slow release fertilizer and lime included. Whether his nursery or my place, we seldomly had to use fungicides. The US people did use the mud mix the other way, and have to use heavy fungicides from time to time. The EU team
used the mud mix by potting the plant in the barely damp mix. Then, spray the top of the pot slightly to make a crust, maybe wet 1 cm of the top, NOT MORE !!!
After the crust formed, and is really hard, water until a couple of drops run out of the bottom of the pot. It means as well that the plants are "moistened", but NEVER watered. The water runs, but of course in such a short time the mix is not completely soaked. We used a crazy 30-10-10 at 1g/L...
Watering the plants would lead to heavy disaster. Brachys especially liked this mix, more than anything else. Repotting every 6 months.
The pH was 4.9, and no rot problems, no sick plants, gorgeous plants. I was using for some species and deflasking the plants until I left Europe. In Viet Nam, the weather is too humid, so it would not be possible to keep the peat dry enough. Boscha Popow grew thousands of species in that mix with the best growing plants one can imagine. I used the same mix and had the very same result. But NEVER, EVER "water", or that's a real disaster. I had everything, including wentworthianum, brachys, dendros cuthbertsonii, tobaense, cattleyas, cyps, calanthe, phals, and all got the very same watering/feeding regimen. roths 4 years from flasks to bloom, easy too... The large plants got the same mix, in clay pot, same watering type.
The mix is no longer suitable for everything too because the peat quality dropped down heavily over the last years in Europe, and the Baltic peat has a different behavior.
Back to the first post, I would be careful because of the vermiculite ( I do not like it, though I have seen beautiful sands in 50/50 perlite/vermiculite mix...), and the wetting agent. You can maybe use it by mixing in about 20% of polyurethan foam, and 5% of bark ( as a component of the "top crust", it helps to spread the water slightly more evenly)