Need some help with my Renanthera monachica

[Ray]

OK. Time for a little "tough love", given in the hope you can learn from many of our mistakes, rather than repeating them.

First, you seem to have used the "shotgun approach" of acquiring plants you like the look of and hoping you can grow them, rather than learning what they want and making sure you can provide that. Pause a minute and do the latter, really analyzing your growing conditions and how you might improve them, then search for plants whose requirements match that. Master growing such plants through a few bloomings and then consider expanding as you gain an overall understanding.

You have a special challenge in your part of the world with lack of humidity. You really should consider improving that. It'll make life on your orchids a lot easier.

Stop moving plants from potting medium to S/H to potting medium to potting medium, hoping you'll find "the right one". It doesn't work that way (not well, anyway). The "trick" is to understand the needs of the plant and decide on the proper container and medium to provide that in your environment. Move it over and pamper the plant while it gets reestablished.

When roots grow, they "tailor" themselves on a microscopic level to function optimally in that environment, and once grown they cannot change. When you move them into another, different environment, they will be less than optimal, and may begin to fail. That's why it's always best to repot just as new roots are emerging from the base of the plant; those new roots will be optimal for that new environment, so will support the plant as the old roots fail. The greater the differences between old and new environments, that faster the old roots will die, and changing it multiple times just stresses the plant over and over.

Your renanthera wants very hot, very bright, and very humid conditions. Give it all three and it'll thrive in a basket with no medium (if you water it often enough), but I found that adding a mesh liner to the basket and adding coarse LECA did a good job of holding moisture around the roots while remaining very airy.